Pump type: guidelines for selecting the correct pump

What is a pump?

A pump is a machine that transports fluid or pressurizes the fluid. It transmits the mechanical energy of the prime mover or other external energy to the liquid, so as to increase the energy of the liquid. The pump is mainly used to transport water, oil, acid-base liquid, emulsion, suspended emulsion, liquid metal and other liquids, as well as liquid, gas mixture and liquid containing suspended solids. Pumps can generally be divided into positive displacement pumps and power pumps according to their working principlesType pumps and other types of pumps. In addition to the classification according to the working principle, they can also be classified and named according to other methods. For example, according to the driving method, they can be divided into electric pumps and water turbine pumps; according to the structure, they can be divided into single-stage pumps and multi-stage pumps; according to the use, they can be divided into boiler feed pumps and metering pumps; according to the nature of the liquid delivered, they can be divided into pumps, oil pumps and mud pumps; according to the structure with or without shaft, they can be divided intoLinear pump, and traditional pump. The pump can only transport the material flow with fluid as the medium, and cannot transport solids.

Operating principle of pump

The impeller is installed in the pump housing and fastened to the pump shaft. The pump shaft is directly driven by the motor. In the center of the pump housing, there is a liquid suction connected to the suction pipe. The liquid enters the pump through the bottom valve and the suction pipe. The liquid outlet on the pump housing is connected to the discharge pipe.
Before the pump is started, the pump casing is filled with the delivered liquid; after the pump is started, the impeller is driven by the shaft to rotate at a high speed, and the liquid between the blades must also rotate with it. Under the effect of centrifugal force, the liquid is thrown from the center of the impeller to the outer edge and gets energy, leaving the outer edge of the impeller at a high speed and entering the volute pump casing. In the volute, the liquid slows down due to the gradual expansion of the flow channel, and then part of the kinetic energy is transferredChange into static pressure energy, and finally enter and discharge at a higher pressureThe ConduitWhen the liquid flows from the center of the impeller to the outer edge, a certain vacuum is formed in the center of the impeller. Since the pressure above the liquid level of the storage tank is greater than the pressure at the pump inlet, the liquid is continuously pressed into the impeller. It can be seen that as long as the impeller continues to rotate, the liquid will be constantly sucked in and discharged.
The working principle of the linear pump is different from that of any other pump. It uses the magnetic suspension principle and the spiral ring hydrodynamic structure to achieve fluid propulsion, that is, cancel the shaft, cancel the shaft connection, and cancel the shaft sealing structure. After starting, the current is converted into a magnetic field, and the magnetic force drives the spiral ring to run, that is, the spiral ring lifts the fluid forward.

Pump application

In the production of chemical and petroleum sectors, most of the raw materials, semi-finished products and finished products are liquids, and the production of raw materials into semi-finished products and finished products requires complex technological processes. Pumps play the role of conveying liquids and providing pressure and flow for chemical reactions in these processes. In addition, pumps are used in many devices to regulate temperature.
In agricultural production, pumps are the main irrigation and drainage machinery. China’s rural areas are vast, and a large number of pumps are needed every year. Generally speaking, agricultural pumps account for more than half of the total pump output.
In the mining and metallurgical industry, pumps are also the most used equipment. The mine needs to use pumps to drain water. In the process of beneficiation, smelting and rolling, pumps are needed to supply water.
In the power sector, nuclear power plants need nuclear main pumps, secondary pumps, tertiary pumps, and thermal power plants need a large number of boiler feed pumps, condensate pumps, oil and gas multiphase pumps, circulating pumps, ash pumps, etc.
In national defense construction, pumps are required for the adjustment of aircraft flaps, tail rudders and landing gears, the rotation of warships and tank turrets, and the sinking and floating of submarines. High pressure and radioactive liquids, some of which also require that the pumps have no leakage.
In a word, no matter aircraft, rockets, tanks, submarines, or drilling, mining, trains, ships, or daily life, pumps are needed everywhere, and pumps are running everywhere. That is why pumps are listed as general machinery, which is a major product in the machinery industry.
The electric pump is an electrically driven pump. The electric pump is composed of the pump body, lifting pipe, pump seat, submersible motor (including cable) and starting protection device. The pump body is the working part of the submersible pump, which is composed of water inlet pipe, guide shell, check valve, pump shaft, impeller and other parts. The impeller can be fixed on the shaft in two ways.

Classification of pumps

1. Centrifugal pump

What is a centrifugal pump?

Centrifugal pumpIt refers to a pump that transports liquid by the centrifugal force generated when the impeller rotates. The centrifugal pump works by centrifugal movement of water caused by the rotation of the impeller. Before the pump is started, the pump shell and suction pipe must be filled with water, and then the motor must be started to make the pump shaft drive the impeller and water to rotate at a high speed. The water is centrifugal and thrown to the outer edge of the impeller to flow through the channel of the volute pump shellPressurized water pipeline of water inlet pump.
The basic structure of centrifugal pump is composed of six parts, namely, impeller, pump body, pump shaft, bearing, seal ring and stuffing box.

1. The impeller is the core part of the centrifugal pump. Its speed is high and its output is high. The blades on the impeller play a major role. The impeller must pass the static balance test before assembly. The inner and outer surfaces of the impeller must be smooth to reduce the friction loss of water flow.
2. The pump body, also known as the pump housing, is the main body of the water pump, which plays a supporting and fixing role and is connected with the bracket for installing the bearing.
3. The function of the pump shaft is to connect with the motor through the coupling to transmit the torque of the motor to the impeller, so it is the main part to transmit mechanical energy.
4. The sliding bearing uses transparent oil as the lubricant, and oil is added to the oil level line. Too much oil will seep out along the pump shaft, and too few bearings will overheat and burn out, causing an accident! During the operation of the pump, the maximum temperature of the bearing is 85 degrees, and generally it is about 60 degrees.
5. The sealing ring is also called leakage reducing ring.
6. The stuffing box is mainly composed of packing, water seal ring, packing cylinder, packing gland and water seal pipe. The purpose of the stuffing box is to close the gap between the pump housing and the pump shaft, so as to prevent the water flow inside the pump from flowing outside and the air from outside from entering the pump. Always keep the vacuum inside the pump! When the pump shaft and the packing friction generates heat, it is necessary to rely on the water seal pipe to trap the water into the water seal ring toPacking cooling! Keep the normal operation of the pump. Therefore, pay special attention to the inspection of the stuffing box during the running patrol inspection of the pump! The packing should be replaced after 600 hours of operation.

Working principle of centrifugal pump
Centrifugal pump works by centrifugal movement of water caused by impeller rotation. Before starting the pump, the pump casing and suction pipe must be filled with water, and then the motor must be started to make the pump shaft drive the impeller and water to rotate at a high speed. The water is centrifugal movement, thrown to the outer edge of the impeller, and flows into the pressurized water pipeline of the pump through the channel of the volute pump casing.
Application of centrifugal pump
Centrifugal pumps can be widely used in power, metallurgy, coal, building materials and other industries to transport slurry containing solid particles. For example, hydraulic ash removal in thermal power plants, slurry transportation in metallurgical concentrators, coal slurry and heavy medium transportation in coal washing plants. When the centrifugal pump works, the pump needs to be placed on land, the suction pipe needs to be placed in water, and the priming pump needs to be started. Due to structural constraints,When working, the motor needs to be placed above the water and the pump into the water, so it must be fixed, otherwise, the motor will be scrapped if it falls into the water. Moreover, because the length of the long shaft is generally fixed, the pump is difficult to install and use, and the application occasions are subject to many restrictions.
Classification of centrifugal pumps
1. Classified by the number of impellers

Single stage pump: there is only one impeller on the pump shaft.
Multi stage pump: that is, there are two or more impellers on the pump shaft, and the total head of the pump is the sum of the heads generated by n impellers.

2. Classified by working pressure

Low pressure pump: the pressure is lower than 100m water column;
Medium pressure pump: the pressure is between 100~650m water column;
High pressure pump: the pressure is higher than 650m water column.

3. Classified by impeller suction pipe

Single side water inlet pump: also called single suction pump, that is, there is only one water inlet on the impeller;
Double suction pump: also known as double suction pump, that is, there is an inlet on both sides of the impeller. Its flow is twice as large as that of the single suction pump, which can be approximately regarded as two single suction pump impellers placed together back-to-back.

4. Classification according to pump casing combination

Horizontal split pump: that is, there is a joint on the horizontal plane passing through the axis line.
Vertical junction surface pump: that is, the junction surface is perpendicular to the axis line.

5. Classified by pump shaft position

Horizontal pump: the pump shaft is in the horizontal position.
Vertical pump: the pump shaft is in a vertical position.

6. Classification by impeller outlet pipe

Spiral case pump: after water comes out of the impeller, it directly enters the pump casing with spiral shape.
Guide vane pump: after water comes out of the impeller, it enters the guide vane set outside it, and then enters the next stage or flows into the outlet pipe.

7. Classification by installation height

Self filling centrifugal pump: the pump shaft is lower than the surface of the suction pool, so it can be started automatically without filling water.
Suction centrifugal pump (non self filling centrifugal pump): The pump shaft is higher than the surface of the suction pool. Before starting, it is necessary to fill the pump housing and suction pipe with water, and then drive the motor to make the impeller rotate at a high speed. The water is thrown out of the impeller under the centrifugal force, and the negative pressure is formed in the center of the impeller. The water in the suction pool enters the impeller under the atmospheric pressure, and is thrown out of the impeller into the water pressure pipe under the action of the high-speed rotating impeller.

In addition, it can also be classified according to the use, such as oil pump, water pump, condensate pump, ash discharge pump, circulating water pump, etc.
Selection guide of centrifugal pump

First, you should know whether the pump you want is used underwater or on the shore. If it is used underwater, there are submersible pumps and underwater pumps. If it is used on the shore, there are vertical and horizontal centrifugal pumps. This should be determined first!
Second, it depends on whether the liquid you take is corrosive. If it is not corrosive, ordinary cast iron and stainless steel centrifugal pumps can be used. If it is corrosive, stainless steel, ordinary plastic and better fluoroplastic materials can be used. The corrosivity of the liquid taken by the customer varies.
Third, it depends on whether there are particles, impurities and fibers in the liquid you hit. If there are no particles or impurities, all centrifugal pumps can hit. If there are particles or impurities or fibers, you should choose a non clogging pump, that is, an open impeller, so that the flow passage of the impeller will not be blocked, or choose a tear pump, and the pump itself has a blade to tear up the debris!
Fourth, whether the pump you want is a direct coupled pump or a coupling pump. Generally, a direct coupled pump connects the motor directly to the pump head, without a base, but with four anchor screw holes for installation, which is unstable, but cheaper. A coupling pump is a pump whose motor is connected to the pump head through bearings and couplings. The pump is overall long, so the pump has a base, so it will not be strong when pumping liquidVibration, safety and stability!
Fifth, it is necessary to know the flow and head of the pump. This is the basic parameter of the pump. Others can be uncertain, but this must be determined. Only by knowing this can we determine the model and size of the pump!

Maintenance of centrifugal pump
Storage of centrifugal pump

① The unpainted surface of the pump that has not been installed should be coated with a layer of appropriate antirust agent. The oil lubricated bearing should be filled with appropriate oil. The grease lubricated bearing should be filled with only one kind of grease, not mixed grease.
② Pump clean the liquid in a short time, flush, suction pipeline, discharge pipeline, pump casing and impeller, and discharge the flushing liquid in the pump casing, suction pipeline and discharge pipeline.
③ Drain the oil from the bearing box, fill it with clean oil, thoroughly clean the grease and fill it with new grease.
④ Seal the suction port and discharge port, store the pump in a clean and dry place, protect the motor winding from moisture, and spray the inside of the pump housing with antirust liquid and anti-corrosion liquid.
⑤ The pump shaft shall be rotated once a month to avoid freezing, and the bearing shall be lubricated.

Matters needing attention
Centrifugal pump is a kind of vane pump. In the process of rotation, depending on the rotating impeller, due to the interaction between the vane and the liquid, the vane transmits mechanical energy to the liquid, so that the pressure of the liquid can be increased and the purpose of conveying liquid can be achieved. Four points should be paid attention to when starting the centrifugal pump:

① The head produced by a centrifugal pump at a certain speed has a limited value. The flow rate and shaft power at the working point depend on the conditions of the device system connected to the pump (potential difference, pressure difference and pipeline loss). The head changes with the flow rate.
② Stable operation, continuous transmission, no pulsation of flow and pressure.
③ Generally, there is no self-priming capacity, and the pump needs to be filled with liquid or vacuum the pipeline before starting to work.
④ The centrifugal pump is started when the discharge pipeline valve is closed, and the vortex pump and axial flow pump are started when the valve is fully open to reduce the starting power.

Because the centrifugal pump lifts the water by the suction of vacuum formed by the centrifugal force of the impeller, the gate valve must be closed and filled with water before the centrifugal pump starts. The water level is above the impeller, and the air in the centrifugal pump can be discharged before starting. After starting, a vacuum is formed around the impeller, and the water is sucked upward. The gate valve can automatically open to lift the water. Therefore, the gate valve must be closed first.
Troubleshooting of centrifugal pump
1. Analysis of mechanical seal failure of centrifugal pump
The shutdown of centrifugal pump is mainly caused by the failure of mechanical seal. The failure is mostly caused by leakage, and the leakage causes are as follows:

① The main reasons for the leakage of the sealing surface of the rotating and stationary rings are: the flatness and roughness of the end face do not meet the requirements, or the surface is scratched; there are particles between the end faces, which causes that the two ends cannot operate equally; the installation is not in place, and the pipeline is incorrect.
② The main reasons for the leakage of the compensation ring seal ring are: the gland is deformed and the preload is uneven; the installation is incorrect; the quality of the seal ring does not meet the standards; and the seal ring is not selected correctly.

The actual use effect shows that the most frequent failure parts of sealing elements are the end faces of dynamic and static rings. Cracking on the end faces of dynamic and static rings of centrifugal pumps is a common failure phenomenon. The main reasons are:

① During installation, the clearance between sealing surfaces is too large, so the flushing fluid cannot take away the heat generated by friction pairs; the flushing fluid leaks from the clearance between sealing surfaces, causing overheating of the end face and damage.
② The liquid medium vaporizes and expands to separate the two end faces by the vaporization and expansion force. When the two sealing faces are forced to fit together, the lubricating film is damaged and the end face surface is overheated.
③ The lubrication of liquid medium is poor, and in addition to the overload of operating pressure, the tracking rotation of two sealing surfaces is not synchronous. For example, the rotating speed of the high speed pump is 20445r/min, the diameter of the sealing surface center is 7cm, and the linear speed of the pump after operation is as high as 75 m/s. When one sealing surface lags behind and cannot track the rotation, the sealing surface is damaged due to the instantaneous high temperature.
④ Sealing flushing fluid orifice plate or filter screen is blocked, resulting in insufficient water volume and mechanical seal failure.

In addition, the sealing element fails due to the sliding groove on the surface of the sealing surface and the notch when the end face is jointed. The main reasons are:

① The liquid medium is not clean, and there are small hard particles, which slide into the sealing surface at a high speed, scratching the surface of the end face and causing failure.
② The coaxiality of the drive parts of the pump is poor. After the pump is started, the end face is shaken and rubbed once every revolution. The running track of the moving ring is not concentric, resulting in end face vaporization and overheating wear.
③ The frequent occurrence of hydraulic characteristics of liquid medium causes the vibration of pump set, resulting in the dislocation of sealing surface and failure.

The corrosion of liquid medium to sealing elements, stress concentration, coordination of soft and hard data, erosion, incompatibility between auxiliary seal 0-ring, V-ring, concave ring and liquid medium, deformation, etc. will cause damage and failure of mechanical seal surface. Therefore, comprehensive analysis should be made on the damage form to find out the root cause and ensure the long-term operation of mechanical seal.
2. Requirements after the centrifugal pump stops running

① After the centrifugal pump stops running, close the inlet valve of the pump, and then close the valves of the auxiliary system in turn after the pump cools down.
② The shutdown of high-temperature pump shall be carried out according to the provisions of equipment science and technology archives. After shutdown, it shall crank for half a circle every 20-30min until the temperature of pump body drops to 50 ℃.
③ When the cryogenic pump is shut down, if there is no special requirement, the pump should always be filled with liquid; the suction valve and discharge valve should be kept open; for the cryogenic pump with double end mechanical seal, the liquid level controller and the sealing liquid in the pump seal cavity should maintain the pump grouting pressure.
④ For pumps conveying media that are easy to crystallize, solidify and precipitate, prevent blocking after stopping the pump, and flush the pump and pipeline with clean water or other media in time.
⑤ Discharge the liquid accumulated in the pump to prevent rust and frost cracking.

2. Vacuum pump

What is a vacuum pump?

A vacuum pump is a device or equipment that uses mechanical, physical, chemical or physicochemical methods to extract air from the evacuated container to obtain vacuum. Generally speaking, a vacuum pump is a device that uses various methods to improve, generate and maintain vacuum in an enclosed space.
According to the working principle of vacuum pump, vacuum pump can be basically divided into two types, namely gas capture pump and gas transmission pump, which are widely used in metallurgy, chemical industry, food, electronic coating and other industries.
With the development of vacuum applications, there have been many types of vacuum pumps, whose pumping speed has increased from a few tenths of a second to hundreds of thousands or millions of liters per second. With the increasing requirements of vacuum technology in the field of production and scientific research for its application pressure range, most of them need several vacuum pumps to form a vacuum pumping system to pump air together to meet the requirements of production and scientific research processesAs the vacuum application department is involved in a wide range of working pressures, it is impossible for any type of vacuum pump to be fully applicable to all working pressure ranges. Different types of vacuum pumps can only be used according to different working pressure ranges and working requirements. In order to facilitate use and meet the needs of various vacuum processesIt shall be combined according to its performance requirements and applied in unit type.
Common vacuum pumps include dry screw vacuum pump, water ring pump, reciprocating pump, slide valve pump, rotary vane pump, roots pump and diffusion pump. These pumps are the essential main pumps in the application of vacuum technology in various industries of China’s national economy. In recent years, with the sustained and rapid development of China’s economy, the downstream application industries related to vacuum pumps have maintained a rapid growth momentum, while vacuum pumpsThe vacuum pump industry in China has achieved sustained, stable and rapid development, driven by the continuous expansion of application fields and other factors.
Operating principle of vacuum pump
Mechanical principle of vacuum pump: a proper amount of water is filled in the pump body as the working fluid. When the impeller rotates clockwise, the water is thrown around by the impeller. Due to the centrifugal force, the water forms a closed ring of approximately equal thickness, which is determined by the shape of the pump cavity. The inner surface of the lower part of the water ring is just tangent to the impeller valley, and the upper inner surface of the water ring is just connected with the top of the bladeContact (actually, the blade has a certain insertion depth in the water ring)At this time, a crescent shaped space is formed between the impeller hub and the water ring, and this space is divided into several small cavities equal to the number of blades by the impeller. If the lower 0 ° of the impeller is taken as the starting point, then the volume of the small cavity will change from small to large 180 ° before the rotation of the impeller, and it is connected with the suction port on the end face. At this time, the gas is inhaled, and when the suction ends, the small cavity will be isolated from the suction portWhen the impeller continues to rotate, the small chamber will change from large to small, so that the gas will be compressed more. When the small chamber is connected with the exhaust port, the gas will be discharged from the pump. In conclusion, the water ring pump realizes suction, compression and exhaust by changing the volume of the pump chamber, so it belongs to the variable volume vacuum pump.
Application of vacuum pump

1. Main pump: vacuum pump used to obtain the required vacuum degree in vacuum system.
2. Rough pumping pump: a vacuum pump that starts from atmospheric pressure and reduces the pressure of the system to another pumping system.
3. Front stage pump: a vacuum pump used to maintain the front stage pressure of another pump below its maximum allowable front stage pressure. The front stage pump can also be used as a rough pumping pump.
4. Maintenance pump: the vacuum system is equipped with an auxiliary front stage pump with small capacity to maintain the normal operation of the main pump or the low pressure required to maintain the evacuated container.
5. Coarse (low) vacuum pump: a vacuum pump that starts from atmospheric pressure, reduces the pressure of the container and operates in the low vacuum range.
6. High vacuum pump: a vacuum pump operating in the high vacuum range.
7. Ultra high vacuum pump: a vacuum pump operating within the ultra-high vacuum range.
8. Booster pump: a vacuum pump (such as mechanical booster pump and oil booster pump) installed between the high vacuum pump and the low vacuum pump to increase the air extraction volume of the air extraction system within the middle pressure range or reduce the capacity requirements of the previous stage pump.

Classification of vacuum pumps
According to the working principle of vacuum pump, vacuum pump can be basically divided into two types, namely gas capture pump and gas transfer pump.
Common vacuum pumps include dry screw vacuum pump, water ring pump, reciprocating pump, slide valve pump, rotary vane pump, roots pump and diffusion pump.
Classification of vacuum pumps
According to the working principle of vacuum pump, vacuum pump can be basically divided into two types, namely gas capture pump and gas transfer pump.
Common vacuum pumps include dry screw vacuum pump, water ring pump, reciprocating pump, slide valve pump, rotary vane pump, roots pump and diffusion pump.
Selection guide of vacuum pump
The function of the vacuum pump is to remove gas molecules from the vacuum chamber, reduce the gas pressure in the vacuum chamber, and make it reach the required vacuum degree. Generally speaking, there is a large range from atmosphere to extremely high vacuum. So far, no vacuum system can cover this range. Therefore, in order to meet the requirements of process quota, work efficiency and equipment service life of different productsDifferent vacuum system configurations shall be selected for the same vacuum section. In order to achieve the best configuration, the following points shall be considered when selecting the vacuum system:
First, the vacuum degree required by each process must be checked and determined. Because each process has its own vacuum degree range, it must be carefully studied and determined.
On the basis of determining the vacuum degree required by the process, check the limiting vacuum degree of the vacuum pump system, because the limiting vacuum degree of the system determines the optimal working vacuum degree of the system. Generally speaking, the limiting vacuum degree of the system is 20% lower than the working vacuum degree of the system, and 50% lower than the extreme vacuum degree of the previous stage pump.
Check and determine the type and amount of air extraction required by the process. If the type of gas to be extracted reacts with the liquid in the pump, the pump system will be polluted. At the same time, it must consider to determine the appropriate exhaust time and the amount of gas generated in the process of air extraction.
Check and determine the time required to reach the required vacuum degree, the flow resistance and leakage of the vacuum pipeline. Consider the pumping rate required to maintain vacuum under certain process requirements after reaching the required vacuum degree.

s=2.303（v/t）lg（p₁/p₂）

In the formula:

S is the pumping rate of vacuum pump (l/s)
V is the volume of vacuum chamber (l)
T is the time required to reach the required vacuum degree (s)
p₁ the initial pressure in the container
p₂ the pressure in the container after air extraction

Influence factor
It determines the size of the product. The higher the air extraction volume is, the larger the product volume is, and the higher the motor power required will be.
It determines the structure of the product. The vacuum degree has two readings: gauge pressure and absolute pressure. Absolute pressure means that the reading is absolute, that is, the closer the reading is to ‘0’, the higher the vacuum degree. However, the closer the gauge pressure is to 760mmH g, the higher the vacuum degree. If you request the absolute pressure (extreme vacuum)If it is close to “0”, only the vacuum pump can meet this demand.
Maintenance of vacuum pump
The quality of the vacuum pump depends on its mechanical structure and the quality of the oil. It must be well protected when using the vacuum pump. If the volatile organic solvent is distilled, the organic solvent will be absorbed by the oil, resulting in an increase in vapor pressure, which will reduce the evacuation performance. If it is acidic gas, it will corrode the pump. If it is water vapor, it will make the oil emulsion and pump the vacuum pump.
Therefore, the following points must be noted when using the vacuum pump:

Absorption device must be installed between distillation system and vacuum pump.
Before distillation, the steam of organic solvent in the system must be completely pumped by water pump.
If it is possible to pump air with a water pump, try to use a water pump. If there are volatile substances in the distilled substances, use a water pump to depressurize and then use a water pump.
The pressure relief system must be kept airtight. All rubber stoppers must be of proper size and holes. The rubber pipes should be vacuum rubber pipes. The ground glass should be coated with vacuum grease.

Vacuum pumps can be divided into three categories according to the scope of use and pumping performance:

(1) For general water pump, the pressure can reach 1.333-100kPa (10-760mmHg), which is “coarse” vacuum.
(2) The pressure of the oil pump can reach 0.133-133.3Pa (0.001-1mmHg), which is the “secondary high” vacuum.
(3) Diffusion pump, the pressure can reach below 0.133Pa, and (10-3mmHg) is “high” vacuum.

If you want a lower pressure, you need to use an oil pump. A good oil pump can pump oil below 133.3Pa (1mmHg).
There are two kinds of pressure reducing pumps commonly used in organic chemistry laboratories: water pump and vacuum pump. If very low pressure is not required, water pump can be used. If the pump is well constructed and has high water pressure, the evacuation efficiency can reach 1067-3333Pa (8-25mmHg) minimum pressure that can be pumped by the water pump is theoretically equivalent to the steam pressure under the water temperature at that time. For example, when the water temperature is 25 ℃, 20 ℃, and 10 ℃, the steam pressure is 3192, 2394, and 1197 Pa (8-25 mmHg) respectively. When the pump is used to pump air, a safety bottle should be installed in front of the pump to prevent the pressure from dropping and the water flow from being sucked back; before stopping the pumping, air should be bled first, and then the pump should be shut down.
Matters needing attention

Pay attention to the following points during daily use and maintenance:

Before starting the equipment, the water inlet shall be opened first, and then the vacuum pump shall be started. In order to prevent backwater from entering the pump body during shutdown, the water inlet shall be closed first and then the pump shall be stopped, preferably the solenoid valve or check valve of the device.
The inlet water of the vacuum pump must be softened and filtered. The inlet water must be of proper size, neither too large nor too small. In order to prevent impurities in the water from blocking the inlet hole, screening procedures shall be installed at the water inlet and regular cleaning shall be carried out.
The vacuum pump has been used in the extreme vacuum for a long time, and the pump will make a lot of noise, which will cause cavitation damage to the pump body. In order to reduce the noise and prevent cavitation, the treatment method is to properly reduce the vacuum. If the production allows, you can open an idle intake pipe to put in a little gas. IV. If the extracted gas contains impurities, you must install screening procedures, otherwise the two ends of the impeller mayStuck and cause failure.
During operation, always check the operation of vacuum pump and motor. If the motor is hot, the measured current is unstable or high, check the pump immediately.
If the drain hole under the connection seat leaks during operation, it means that a small amount of water in the mechanical seal pool can continue to be used. Serious water leakage should be stopped for repair.
Regularly remove the scale in the pump, and keep the two ends of the impeller close and proper clearance.
After a long time of shutdown, before starting again, the motor protective cover should be removed. When the motor fan is rotated manually, it can rotate flexibly before starting again. If it is a long-term shutdown or winter shutdown, the accumulated water in the pump should be drained to prevent rust in the pump body from seizing the impeller.

Troubleshooting of vacuum pump
1. High motor temperature
The causes of high temperature of vacuum pump motor are analyzed as follows.
Cause analysis
(1) The motor has large power, large working current and large heat generation.
(2) Fan speed is low, air pressure and air volume are small.
(3) The number of fan blades is small, resulting in small air volume.
(4) The motor is attached with dust and oil, which reduces the heat dissipation capacity.
(5) The voltage of the bus where the vacuum pump motor is located is 380V. Due to the uneven cable voltage drop and load distribution, the actual applied voltage of the motor is only 365V. The low voltage results in high running current.
Countermeasure
The motor power and speed are matched with the vacuum pump and cannot be changed. The fan is installed on the main shaft of the motor. The motor speed determines the fan speed and cannot be replaced. Although the number of new fan blades can play a role, it is difficult to find the dynamic balance after the number of new fan blades is increased. If the alignment is not good, it will cause new motor vibration.
（1）The original fan cover is lengthened by 40cm, and an axial flow fan with the same diameter as the fan cover is installed inside. The axial flow fan motor power is 850W, rotating speed is 1489r/min, and voltage is 380V. The original fan continues to be retained. The axial flow fan is equipped with another power supply control, and the axial flow fan is not interlocked with the main motor. After the vacuum pump is started, the axial flow fan is started in time, and the axial flow fan is stopped 30 minutes after the vacuum pump is stopped toMake the main motor fully cooled;
(2) Regularly remove the dust on the motor, keep the motor cooling fin clean, and increase its cooling capacity;
(3) Adjust the voltage of the bus where the vacuum pump is located to 400V.
Effect
(1) Due to the high speed of the axial flow fan, large air pressure and volume, the cooling effect is greatly enhanced. Under the same ambient temperature and load current, the temperature of the main motor decreases by 12 ℃. The temperature of the main motor does not exceed the limit in summer.
(2) The axial flow fan can be controlled manually. After the main motor stops, the axial flow fan can still operate, which can fully cool the main motor.
(3) Try to balance the load distribution of the two bus sections to prevent excessive voltage drop of a bus section due to overload.
(4) After the voltage is adjusted, the operating current of the vacuum pump is reduced to 210A, and the heat generation is relatively reduced.
(5) The insulation aging speed of the main motor is slowed down and its service life is extended.
2. Wear of pump shaft bearing bits
The wear of vacuum pump transmission parts is a common problem, including bearing bits, bearing seats, bearing chambers, keyways and threads. The traditional methods mainly use repair welding and brush plating spraying, but both have certain disadvantages: the thermal stress caused by the high temperature of repair welding cannot be completely eliminated, which is easy to cause material damage, resulting in bending or fracture of parts; while the brush plating is affected by the coating thicknessLimited, easy to peel off, and the above two methods are to repair metal with metal, which cannot change the “hard to hard”Under the combined effect of various forces, it will still cause re wear. Modern western countries use polymer composite repair methods to solve the above problems, while the American Meijiahua technology system is more widely used, which has super adhesive force, excellent compressive strength and other comprehensive properties. Using polymer materials to repair can avoid disassembly and machining. Neither repair weldingUnder the influence of thermal stress, the repair thickness is not limited. At the same time, the metal materials of the product do not have the flexibility, which can absorb the shock and vibration of the equipment, avoid the possibility of re wear, and greatly extend the service life of equipment components, save a lot of downtime for enterprises, and create huge economic value.
3. Corrosion
The corrosion form of vacuum pump can be divided into comprehensive (uniform)Corrosion and local corrosion, the former occurs evenly on all surfaces of the vacuum pump, while the latter only occurs locally, such as pitting corrosion, crevice corrosion, intergranular corrosion, stress corrosion, etc. Polymer composite materials are used to apply organic coating on the surface of the vacuum pump for corrosion prevention, which has good chemical resistance, excellent mechanical properties and bonding properties, and is welded with traditional pressure vesselsCompared with repair, it has the characteristics of simple construction, low cost, safe performance and good repair effect.
4. Shell crack and fracture
Due to casting and processing defects, internal stress, overload operation and other reasons, the vacuum pump often causes cracks or fractures in its components. The conventional repair method is welding, but some parts are made of cast iron, aluminum alloy, titanium alloy, which is difficult to weld. In some dangerous situations, it is even more difficult to use the welding repair method. Meijiahua Technology is a “cold welding”Science and technology can avoid thermal stress deformation. At the same time, good adhesion, compression resistance, corrosion resistance and other comprehensive properties of data can meet the use requirements of various equipment components to the maximum extent, so as to effectively ensure production at the lowest cost. It is safe, convenient and reliable.
5. Smoke and fuel injection

1. Smoke. It is normal if the pump has just started to run, but it is abnormal if it smokes for a long time. Solution: Smoke indicates that there is repair outside the air inlet of the pump, including pipes, valves and containers. Smoke will end if it is handled after leak detection.
2. Fuel injection indicates that there are a lot of leakage points outside the air inlet, even the air inlet is exposed to the atmosphere. The solution: seal the air inlet of the pump to make the pump run. If no fuel injection is used, it indicates that there are leakage points; the exhaust valve plate is damaged, check whether the exhaust valve plate is damaged, and replace the damaged exhaust valve.

3. Screw pump

What is a screw pump?

Screw pump is a rotary pump that transports liquid or pressurizes it by relying on the volume change and movement of the meshing space formed by the pump body and the screw. The screw pump is divided into single screw pump, twin screw pump and three screw pump according to the number of screws. When the active screw rotates, it drives the driven screw engaged with it to rotate together. The volume of the screw meshing space at one end of the suction chamber gradually increases and the pressure decreases.The liquid enters the meshing space volume under the effect of pressure difference. When the volume increases to the maximum and a sealing chamber is formed, the liquid will continuously move along the axial direction in one sealing chamber until one end of the discharge chamber. At this time, the volume of the screw meshing space at one end of the discharge chamber gradually shrinks, and the liquid will be discharged. The working principle of the screw pump is similar to that of a gear pump, except that the screw is used to replace it in structureGear. The table shows the characteristics and application range of various screw pumps. The screw pump has very small flow and pressure pulse, low noise and vibration, and is capable of self-priming, but it is difficult to process the screw. The pump has two types of structures: single suction type and double suction type, but the single screw pump only has a single suction type. The pump must be equipped with a safety valve (single screw pump is not necessary)To prevent the pump or prime mover from being damaged due to the outlet pressure of the pump exceeding the allowable value due to some reason, such as blockage of the discharge pipe.
Working principle of screw pump
1. The screw pump uses the rotation of the screw to suck and discharge liquid. The figure shows the sectional view of the three screw pump. In the figure, the middle screw is the active screw, which is driven by the prime mover to rotate, and the screws on both sides are driven screws, which rotate inversely with the active screw. The threads of the driven screw and the driven screw of the active screw are double headed threads.
Due to the mutual engagement of the screws and the close cooperation between the screws and the inner wall of the liner, between the suction and discharge ports of the pump, it will be separated into one or more sealing spaces. With the rotation and engagement of the screws, these sealing spaces will continue to form at the suction end of the pump, seal the liquid in the suction chamber, and move continuously from the suction chamber to the discharge end along the screw axisThe liquid enclosed in each space is constantly discharged, just like the case where a nut is constantly pushed forward when the thread rotates, which is the basic working principle of the screw pump.
2. The working principle of the screw pump is that when the screw pump is working, the liquid is sucked into the sealing space between the screw thread and the pump housing. When the active screw rotates, the sealing volume of the screw pump increases the pressure of the screw pump under the extrusion of the screw thread and moves along the axis. Since the screw rotates at the same speed, the liquid outflow flow is also uniform.
The screw pump is characterized by small loss, good economic performance, high and uniform pressure, uniform flow, high speed, and direct connection with the prime mover.
Screw pump can be used to transport lubricating oil, fuel oil, various oils and high molecular polymers, and viscous liquids.
Transportation of high viscosity media: 3. Depending on the size of the pump, the medium with viscosity ranging from centipoise can be transported.
Medium containing particles or fibers: the particle diameter can be 30mm (not exceeding the rotor eccentricity). The fiber length can be 350mm (equivalent to the screw pitch of 0.4 bit rotor). Its content can generally reach 40% of the medium pit. If the solid in the medium is in the form of fine powder, the maximum content can reach 60% or more.
When the conveying pressure is required to be stable and the inherent structure of the medium is not damaged, the single screw pump is the best choice for conveying.
Application of screw pump
Single screw pump can be used to transport single or multiple medium fluids, including neutral or corrosive, clean or abrasive, gas containing or easy to generate bubbles, high viscosity or low viscosity, and liquids containing fibers or solid particles, which are widely used in various industrial departments.
Sewage treatment: sewage and sewage oil, sludge containing solids and various agents. Chemical industry: acid, alkali, salt, various viscous paste emulsions, molding ointment, dye, pigment, ink and paint. Energy industry: various fuels (heavy oil, crude oil, diesel oil)Oil coal slurry, coal water slurry, coal slime and nuclear waste. Paper industry: treatment of various cellulose and pulp, coating black liquor, etc. Ceramic industry: porcelain clay, refractory clay, glaze, bentonite, white carbon black. Exploration and mining: multiphase transportation of various drilling mud, tunnel engineering, oil, water, and concrete. Medicine, food, and cosmetics: various syrup, jam, starch paste, pasteHops, mashed potatoes, alcohol, chocolate, etc.
Classification of screw pumps
Screw pumps are classified according to the number of screws.

Single screw pump – a pump in which a single screw engages and rotates in the internal thread groove of the pump body.
Twin screw pump – a pump that transports liquid by meshing two screws.
Three screw pump – a pump that transmits liquid by meshing multiple screws.

Selection guide of screw pump
Screw pump is widely used in the sewage treatment plant to transport water, wet sludge and flocculant liquid due to its characteristics of variable transmission, strong self-priming capacity, reversibility and the ability to transport liquid containing solid particles. The selection of screw pump should follow the principles of economy, rationality and reliability. If the design and selection of screw pump is not well considered, it will give future use, management and maintenance beltsTherefore, a reasonable and reliable screw pump according to the actual production needs can not only ensure the smooth production, but also reduce the repair cost.
1、 Rotating speed selection of screw pump
The flow of the screw pump is linear with the speed. Compared with the screw pump with low speed, the high speed screw pump can increase the flow and head, but its power is significantly increased. The high speed speeds up the wear between the rotor and stator, which must make the screw pump fail prematurely. In addition, the stator and rotor of the high speed screw pump are very short and easy to wear, thus shortening the service life of the screw pump.
Reduce the speed through the speed reducer or stepless speed regulator to keep the speed below 300 revolutions per minute. Compared with the high-speed screw pump, the service life can be extended several times.
2、 Mass of screw pump
There are many kinds of screw pumps. Relatively speaking, the imported screw pumps have reasonable design and excellent materials, but their prices are high. Some of them are less than the standard in terms of service. The price of accessories is high, and the order cycle is long, which may affect the normal operation of production.
Most of the domestic products are imitated from imported products, and the quality of the products is mixed. When selecting the domestic products, the products with low speed, long lead, good transmission components and long rated life should be selected when considering their cost performance ratio.
3、 Ensure that no sundries enter the pump body
The solid sundries mixed in the wet sludge will damage the rubber stator of the screw pump, so it is important to ensure that sundries do not enter the pump chamber. Many sewage plants have installed shredders in front of the pump, and some have installed grating devices or filters to prevent sundries from entering the screw pump. The grating should be removed in time to avoid blocking.
4、 Avoid material break
The screw pump is never allowed to run under the condition of material interruption. Once it happens, the rubber stator will burn out due to dry friction and instant high temperature. Therefore, it is one of the necessary conditions for the normal operation of the screw pump that the grinder is in good condition and the grid is unblocked. For this reason, some screw pumps are also equipped with a material interruption shutdown device on the pump body. In case of material interruption, the screw pump has a self-priming function,Vacuum will be generated in the chamber, and the vacuum device will stop the screw pump.
5、 Maintain constant outlet pressure
The screw pump is a positive displacement rotary pump. When the outlet end is blocked, the pressure will gradually increase, so that it exceeds the predetermined pressure value. At this time, the motor load will increase sharply. The load of related parts of the transmission machinery will also exceed the design value, and in serious cases, the motor will be burned and the transmission parts will be broken. In order to avoid damage to the screw pump, an oil return valve will be installed at the outlet of the screw pumpTo stabilize the outlet pressure and maintain the normal operation of the pump.
Maintenance of screw pump
1. Daily maintenance
Check the oil level in the gear box when the screw pump stops. If necessary, remove the oil filling plug and add oil to the center of the oil pointer.
Listen for abnormal noise and vibration.
Check the pump for leaks when the pump is running.
Note: For mechanical seals, in most cases, no leakage can be observed from the seal drain hole due to vaporization, but sometimes a small and stable leakage is allowed.
2. Weekly inspection and maintenance
For pumps that have stopped working for more than a week, open the inlet and outlet valves, connect the motor power supply, and jog the pump several times.
Check whether the valves on the inlet and outlet pipes can work normally.
3. Quarterly maintenance
Check whether the nuts on all foundations and the bolts of the clamping device are loose.
According to the installation regulations, the oil in the gearbox should be replaced every three months. Loosen the drain plug of the gearbox to drain the gear oil. Tighten the drain plug, open the oil filling plug, inject clean light oil, and clean the gearbox. After cleaning, open the drain plug, drain the light oil, tighten the drain plug, inject the specified gear oil from the oil filling plug hole to the middle of the oil pointer, and tighten the oil filling screw
4. Annual maintenance
Check the alignment of the coupling.
Check the flow, pressure and power of the pump against the values of the pump and the motor. If necessary, when the pressure and flow drop a lot, the pump should be disassembled and overhauled, and the damaged parts should be replaced and repaired. Of course, if the performance of the pump is still satisfactory, there is no need to disassemble and repair the pump.
5. Oil change time of lubricating oil system
Add 3 # universal lithium base grease to the bearing once a month.
The gear oil of the new gear box pump has been changed for 250 hours accumulatively; the same gear oil mentioned above has been changed every 1000 hours of continuous operation.
Mechanical seal oil: ensure that the oil level is in the center of the inspection hole when the machine is shut down, replenish it daily as the case may be, and replace it every six months.
Matters needing attention

1. During assembly, the screw pump parts shall be carefully cleaned and checked, and the damaged parts shall be replaced;
2. When assembling the two universal joints of the transmission shaft, check whether the sealing ring is damaged and fill the cavity with grease;
3. Properly installed bearings enable the shaft to rotate flexibly without jamming.
4. Installation of shaft seal: when installing the stuffing box, the position of the gland pressing bolt should be within the installation window of the housing to facilitate the wrench to adjust the bolt;
5. When tightening the exhaust body pressure, the nuts shall be tightened uniformly;
6. The mechanical seal shall be installed carefully, and the friction pair end face shall be clean and coated with grease;
7. When installing the stator, coat the rotor and the surface of the stator inner cavity with lubricating oil to facilitate the installation of the stator;
8. During installation and assembly, coupling installation deviation: △ Y ≤ 0.2mm, △ α ≤ 30.

Troubleshooting of screw pump
1. The pump body vibrates violently or produces noise:
Causes: The water pump is not firmly installed or is too high; the ball bearing of the motor is damaged; the main shaft of the water pump is bent or not concentric or parallel with the main shaft of the motor.
Treatment method: steadily install the water pump or reduce the installation height of the water pump; replace the motor ball bearing; correct the bent water pump spindle or adjust the relative position of the water pump and the motor.
2. Overheating of drive shaft or motor bearing:
Cause: lack of lubricating oil or bearing fracture.
Treatment method: add lubricating oil or replace the bearing.
3. No water from the water pump:
Causes: the pump body and suction pipe are not fully filled with water; the dynamic water level is lower than the pump filter pipe; the suction pipe is broken, etc.
The sealing surface between the screw and the shell is a spatial surface. There are non sealing areas such as ab or de on this surface, and many triangular notches abc and def are formed with the groove of the screw. These triangular notches form a channel for liquid, so that the groove A of the active screw is connected with the grooves B and C of the driven screw. The grooves B and C are wound along their own spiral linesIt faces the back side and is connected with grooves D and E on the back side respectively. Since there is a triangular notch a’b’c ‘similar to the front side on the sealing surface where grooves D and E are connected with grooves F (which belongs to the spiral at the other end), D, F and E will also be connected. In this way, groove ABCDEA will also form an “∞” shaped sealing space(If a single head thread is used, the groove will wrap the screw along the axial direction, connecting the suction and discharge ports, and can not form a seal). It is not difficult to imagine that many independent “∞” will be formed on such a screwThe axial length occupied by each sealing space is exactly equal to the lead t of the rod. Therefore, in order to separate the oil suction and discharge ports of the screw, the length of the screw thread section must be at least greater than one lead.

4. Gear pump

What is a gear pump?

Gear pump is a rotary pump that transports liquid or pressurizes it by means of the change and movement of working volume formed between the pump cylinder and the meshing gear. It consists of two closed spaces composed of two gears, the pump body and the front and rear covers. When the gear rotates, the volume of the space on the side where the gear disengages increases from small to large, forming a vacuum, sucking in the liquid, and the volume of the space on the meshing side of the gear decreases from large to small, thus reducing the volume of the liquidThe suction chamber and discharge chamber are separated by the meshing line of two gears. The pressure at the discharge port of the gear pump completely depends on the resistance at the pump outlet.
Working principle of gear pump
When the gear pump is working, the driving wheel rotates with the motor and drives the driven wheel to rotate with it. When the meshing teeth on one side of the suction chamber gradually separate, the volume of the suction chamber increases and the pressure decreases, so the liquid in the suction pipe is sucked into the pump; the inhaled liquid is pushed to the discharge chamber by the gear wheel in two ways in the gear slot. After the liquid enters the discharge chamber, the gear teeth of the two gears are constantly meshed,The liquid is squeezed into the discharge pipe from the discharge chamber. The driving gear and driven gear rotate continuously, and the pump can continuously inhale and discharge liquid.
The pump body is equipped with a safety valve. When the discharge pressure exceeds the specified pressure, the delivery liquid can automatically open the safety valve to return the high-pressure liquid to the suction pipe.
Application of gear pump
Gear pumps are mainly used for oil medium transfer, pressurization, fuel injection, etc. in petroleum, chemical industry, metallurgy, mining, power station and other industries, as well as thin oil circulation in large mechanical equipment. They can be used as lubrication pumps in various mechanical equipment.
Classification of gear pumps
As far as the core component gear is concerned, it mainly consists of the common normal gear pump and the circular arc gear pump. The common normal gear pump is more durable than the circular arc gear pump in conveying media containing impurities, while the circular arc gear pump has special structure, delivering clean media, low noise, long service life, and each has its own advantages.
Selection Guide of Gear Pump
The factors to be considered in gear pump selection include working pressure, flow, speed, quantitative or variable, variable pipeline, volumetric efficiency, total efficiency, life, type of prime mover, noise, pressure pulsation rate, self-priming capacity, etc., as well as compatibility with hydraulic oil, size, weight, economy, maintainability, etc. Some of these factors have been written in product samples or technical dataIn case of any ambiguity, it is better to consult the gear pump manufacturer for the correct method of gear pump selection.
Maintenance of gear pump
When using the gear pump, it is unavoidable to touch the wear of the gear pump, so many problems will occur, so we should learn the most common maintenance technology for the gear pump. If there is a problem, we can make an accurate judgment on it. Next, I will tell you about the most common maintenance technology:

1. Maintenance of the working surface: if the wear of the working surface of the pump cover is relatively small, you can remove the wear marks by grinding yourself, that is, put a little valve sand on the platform or thick glass plate, and then put the pump cover on it for grinding until the wear marks are removed and the working surface is flat. If the wear depth of the working surface of the pump cover exceeds 0.1 mm, you should first turn the pump cover atGrinding to repair.
2. Maintenance of driving shaft bushing hole: the maintenance of driving shaft bushing hole wear on the pump cover is the same as that of housing driving shaft bushing hole wear. Repair of pump casing inner cavity: after the pump casing inner cavity is worn, the inner cavity inlay method is adopted for repair, that is, the inner cavity is lined up and then equipped with cast iron or steel bushing. After the lining is inserted, the inner cavity is lined up to the required size, and the bushing protruding from the end face is rubbed off, which should be flush with the pump casing junction surface.
3. Maintenance of valve seat: There are two types of pressure limiting valves: spherical valve and plunger valve. After the spherical valve seat is worn, place a steel ball on the valve seat, and then gently tap the steel ball with a metal rod until the ball valve and the valve seat are tight. If the valve seat is severely worn, it is necessary to ream to remove the wear marks, and then use the above method to make it tight. After the plunger valve seat is worn, put a little valve sand to grind it until it is tight close.

The above is about the maintenance of the most basic parts of the gear pump. We may encounter different problems in other aspects during the application process. We should also carefully discuss these different problems to find out the causes of these problems.
Matters needing attention
The gear pump is suitable for various industries, with a wide range of media to be transported. This gear pump has the advantages of firm structure, convenient installation, easy disassembly, simple maintenance, uniform and continuous flow, slight wear, long service life, etc.

1. During the process of using the gear pump, grease should be added frequently, because the grease is easy to volatilize, so attention must be paid to the replacement, and then the bearing should be kept clean;
2. Put the electric oil well pump in a dry, non corrosive and clean environment when it is used or after use;
3. The gear pump should be checked and maintained frequently during use. Pay attention to checking the power line in the electric oil tank; whether the internal wiring, plug and switch can be used normally; whether the bearing parts are damaged, etc;
4. Each part of the gear pump shall be stored and kept clean during disassembly and inspection of the gear pump。

Troubleshooting of gear pump
1. No nesting

Fault phenomenon: the pump cannot discharge.
Fault causes: a. The rotation direction is opposite; b. The suction or discharge valve is closed; c. There is no material at the inlet or the pressure is too low; d. The viscosity is too high and the pump cannot bite.
Countermeasures: a. Confirm the direction of rotation; b. Confirm whether the valve is closed; c. Check the valve and pressure gauge; d. Check the liquid viscosity, and check whether the flow proportional to the speed occurs at low speed. If there is flow, the flow is insufficient.

2. Insufficient flow

Symptom: insufficient pump flow.
Fault causes: a. Suction or discharge valve is closed; b. Inlet pressure is low; c. Outlet pipeline is blocked; d. Packing box leaks; e. Rotating speed is too low.
Countermeasures: a. Confirm whether the valve is closed; b. Check whether the valve is open; c. Confirm whether the discharge is normal; d. Tighten; When a large amount of leakage affects production, stop the operation and disassemble it for inspection; e. Check the actual speed of the pump shaft.

3. Abnormal sound

Symptom: abnormal sound.
Cause of fault: a. Large eccentricity or poor lubrication of coupling b. Motor fault; c. Abnormal reducer; d. Poor installation of shaft seal; e. Shaft deformation or wear.
Countermeasures: a. Align or fill lubricating grease; b. Check the motor; c. Check the bearing and gear; d. Check the shaft seal; e. Shut down for disassembly inspection.

4. Excessive current

Fault phenomenon: excessive current.
Fault causes: a. The outlet pressure is too high; b. The melt viscosity is too high; c. The shaft seal is poorly assembled; d. The shaft or bearing is worn; e. The motor is faulty.
Countermeasures: a. Check the downstream equipment and pipelines; b. Check the viscosity; c. Check the shaft seal and adjust it properly; d. Check whether the manual barring is too heavy after shutdown; e. Check the motor.

5. Pump stop

Fault phenomenon: the pump stops suddenly.
Fault causes: a. Power failure; b. Motor overload protection; c. Coupling damage; d. High outlet pressure, interlock reaction; e. Abnormal biting in the pump; f. Sticking between shaft and bearing.
Countermeasures: a. Check the power supply; b. Check the motor; c. Open the safety cover and turn the gear for inspection; d. Check the instrument interlocking system; e. After stopping, confirm the positive and negative turning of the gear; f. Confirm the turning of the gear.

6. Seal oil leakage

Fault phenomenon: seal leaks oil.
Causes: a. The shaft seal is not adjusted properly; b. The seal ring is worn and has large clearance; c. The friction surface of the dynamic and static rings of the mechanical seal is damaged; d. The spring is loose.
Countermeasures: a. Readjust; b. Tighten the gland bolts properly or replace the seal ring; c. Replace the moving and stationary rings or regrind; d. Replace the spring.

5. Axial flow pump

What is an axial flow pump?

Axial flow pumps are vertical, horizontal, inclined and tubular pumps that deliver liquid along the axis direction by the force generated by the blades of the rotating impeller on the liquid. The axial flow pump impeller is equipped with 2-7 blades that rotate in the cylindrical pump housing. The pump housing on the upper part of the impeller is equipped with fixed guide vanes to eliminate the rotating motion of the liquid, turn it into axial motion, and turn the kinetic energy of the rotating motion into axial motionIt is converted into pressure energy. Axial flow pumps are usually single-stage, and a few are two-stage. The flow range is large, ranging from 1.8 to 3.6 million cubic meters per hour; the head is generally below 20 meters. Axial flow pumps are generally vertical, with the impeller submerged under water, and there are also horizontal or oblique axial flow pumps. When the impeller of small axial flow pumps is installed above the water surface, it needs to be started by exhaust and diversion of vacuum pumps. The blades of axial flow pumpsIt is divided into fixed and adjustable structures. Operating conditions of large axial flow pump (mainly flow)It is often necessary to make large changes during operation. Adjusting the installation angle of the blades can keep the pump operating in the high efficiency area under different working conditions. The installation angle of the blades of small pumps is generally fixed. Axial flow pumps are among the power pumps with the highest specific speed, which is 500-1600. The flow head and flow shaft power characteristic curves of the pump are steeper in the small flow area, so it is necessary to avoidStable operation in small flow area. The axial flow pump has the largest axial power at zero flow, so the valve on the discharge pipeline must be opened before starting the pump to reduce the starting power. The axial flow pump is mainly suitable for occasions with low lift and large flow, such as irrigation, waterlogging drainage, dock drainage, water level regulation of Yunhe Shiplock, or used as a large circulating pump in power plants. The axial flow pump with high lift(If necessary, it can be made into two stages), which can be used for water jet propulsion of shallow water ships.
Operating principle of axial flow pump
If the wing is suspended in the fluid and the fluid flows at a certain speed, negative pressure will occur on the wing surface and positive pressure will occur on the wing back. The magnitude of the positive and negative pressure is related to the wing shape and angle of attack (the inclination of the wing back to the direction of fluid flow), as well as the fluid speed.
If the fluid does not move, but the wing moves in the fluid at the same speed, the wing back and wing surface are subject to the same positive pressure and negative pressure as before, that is, the wing surface (above the wing) is negative pressure, and the wing back is positive pressure. Under this pressure, the wing will obtain lift.
If the wing shaped blades are fixed on the rotating shaft to form a propeller and make it unable to move along the axial direction, when the rotating shaft rotates at high speed, the wing surface (lower side of the propeller) has a suction effect due to negative pressure, and the wing back has a drainage effect due to positive pressure, so that the liquid (or gas) flow is caused by one row of suction. This is the working principle of the axial flow pump.
Application of axial flow pump
Axial flow pumps are mainly suitable for low lift and large flow occasions, such as irrigation, waterlogging drainage, dock drainage, water level regulation of canal locks, or large circulating water pumps in power plants. Axial flow pumps with high lift (made into two stages if necessary) can be used for water jet propulsion of shallow water ships.
Classification of axial flow pumps
According to the relative position of the pump shaft, there are three types: vertical (the pump shaft is placed vertically), horizontal (the pump shaft is placed horizontally) and oblique. The vertical axial flow pump is easy to start when working, and occupies a small area. Most of the current production is vertical.
According to the possibility of blade adjustment, it can be divided into three types: fixed blade axial flow pump, semi adjustable blade axial flow pump and full adjustable blade axial flow pump. Among them, the semi adjustable type can adjust the flow and head, and its structure is simple and easy to manufacture. Therefore, most axial flow pumps are semi adjustable.
Selection guide of axial flow pump
Maintenance of axial flow pump
1. Disassembly method for maintenance of axial flow pump: before disassembly, mark the joints between the front and rear end covers and the machine base with a chisel. Because the assembly of the motor at the factory is quite reasonable, if it is not assembled as it is after repair, it may cause slight errors and cause inflexibility of the shaft. When disassembling, carefully observe the burn out degree of the winding, preliminarily analyze the cause of the burn out, and pay attention to the slightFaults that are easy to see, such as bore cleaning and ball breakage.
When dismantling and repairing the axial flow pump for maintenance and clicking on the broken winding, pay attention to protect the iron core and plastic retainer. If the method is not suitable, the iron core may expand and be disabled. When the motor is powered on, electromagnetic effects may occur, which may cause vibration of the iron core and vibration of the winding itself, and it is very easy to cause insulation damage of insulating paper and electromagnetic wire.
2. The self-made wire mold shall be assembled: the wire embedding shall be correct. After one phase is embedded, another phase shall be embedded to form a “three layer plane” at the end. The end must be firmly bound to prevent scratches during assembly.
3. The position of the “limit screw” shall be adjusted carefully to ensure that the rotor can rotate freely and the no-load current is the minimum, which is the best state. Then the lock nut must be tightened.
4. Waterproof and insulation of joints shall be properly treated. Sheath and insulation layer shall be stripped off at the joints, and paint layer and oxide layer on the surface of copper wire shall be removed. Tin welding shall be performed after splicing. Then sharp corners, burrs and welding fluid shall be removed. Six layers of polyethylene tape shall be half folded, and two layers of tapestry adhesive tape shall be half folded, as the mechanical protective layer.
Matters needing attention

1. During trial operation, the connection parts shall be checked to ensure that there is no looseness.
2. Electrical appliances and instruments work normally; oil, gas and water system pipes shall be free of leakage; pressure and hydraulic pressure are normal.
3. Frequently check whether there are floating objects near the water inlet to prevent blockage of the water inlet.
4. The temperature of rolling bearing of axial flow pump shall not be greater than 75 ℃.
5. Pay attention to the sound and vibration of the water pump at any time, and immediately shut down for inspection in case of any abnormality.
6. The oil temperature in the gearbox shall be normal.

Troubleshooting of axial flow pump
1. Common failure of axial flow pump: insufficient water output
Insufficient water output of the pump is a common fault of the axial flow pump. During its use, due to some reasons (such as impeller damage)This will lead to insufficient water output of the pump, which is also inseparable from the working conditions of the axial flow pump. Therefore, its working conditions need to be improved, and the modification must be carried out in accordance with the manufacturer’s regulations. In addition, the blade angle must be adjusted, and the impeller or the pump body section outside the impeller shall be repaired or replaced.
2. Common fault of axial flow pump: no water is discharged after the pump is started
When such a problem occurs, it is necessary to adjust the rotation direction of the water pump, find out the reason why the speed of the water pump decreases, clean up the blockage, and take immediate measures to solve the problem if there is water leakage in the pipeline.
3. The common failure of axial flow pump is that the pump vibrates and sounds during operation
During the operation of the axial flow pump, some vibration and noise sometimes occur. The fault can also be judged by different noises, which were specifically introduced in the previous article. However, the vibration and noise of the pump in operation are often caused by the damage of the impeller, the looseness of the anchor bolt, and other reasons. The solution is to increase the submergence depthAdd a board on the water surface of the pool to replace the impeller. If the foundation bolt is loose, tighten the foundation bolt and strengthen the foundation. In addition, if the bearing has a problem, it will also lead to this condition. Therefore, it is necessary to replace the rubber bearing, or spray hard chrome on the bearing contact to feed water into the pumpRearrange the rows and realign the pump shaft.
4. Common fault of axial flow pump: power machine overload
Overload of power machine is also one of the common faults of axial flow pump. The main reasons for this phenomenon are improper selection of power machine, wear of bearing or impeller, wrong blade angle, high speed of water pump. Therefore, when selecting power machine, it is necessary to select a suitable power machine, replace the bearing or impeller, and adjust the blade angle properlyLoad is enough. Reduce the pump speed by replacing the power machine or impeller and make it reach the rated value.

6. Magnetic pump

What is a magnetic pump?

Magnetic pump (magnetic drive pump) mainly consists of pump head, magnetic actuator (magnetic cylinder)When the motor drives the external magnetic rotor to rotate, the magnetic field can penetrate the air gap and non-magnetic substances, drive the internal magnetic rotor connected to the impeller to rotate synchronously, realize the non-contact synchronous transmission of power, and seal the dynamic seal that is easy to leakSince the pump shaft and inner magnetic rotor are completely sealed by the pump body and the isolation sleeve, the problem of “running, emitting, dripping and leaking” is completely solved.
Working principle of magnetic pump
The magnet of the brushless DC magnetic drive pump and the impeller are molded into a whole to form the rotor of the motor. There is a shaft sleeve directly molded in the middle of the rotor, which is fixed in the housing through a high-performance ceramic shaft. The stator and circuit board of the motor are sealed in the pump body with epoxy resin glue. There is a thin wall isolation between the stator and the rotor, which does not need to be matched with a traditional mechanical shaft seal, so it is completely sealedThe torque of the motor is generated by the magnetic field generated after the coil on the silicon steel sheet (stator) is energized to drive the permanent magnet (rotor) to work. Conduct n (n is an even number) on the magnetStage magnetization makes the magnet parts form a complete coupled magnetic system with each other. When the magnetic pole generated by the stator coil is opposite to the magnetic pole of the magnet, that is, the displacement angle Φ=0 between the two magnetic poles, the magnetic energy of the magnetic system is the lowest; when the magnetic poles rotate to the opposite of the same pole, that is, the displacement angle Φ=2 π/n between the two magnetic poles, the magnetic energy of the magnetic system is the largest. After the external force is removedThe magnetic poles repel each other, and the magnetic force will restore the magnet to the lowest state of magnetic energy, so the magnet will move and drive the magnetic rotor to rotate.
Brushless DC water pump uses electronic commutation without the use of carbon brushes. Both the magnet rotor and stator silicon steel sheet have multistage magnetic fields. When the magnet rotor rotates an angle relative to the stator, it will automatically change the direction of the magnetic pole, so that the rotor always maintains the same level repulsion, so that the brushless DC magnetic isolation pump has a higher speed and efficiency.
The stator and rotor of the magnetic isolation pump are completely isolated, which completely avoids the liquid leakage problem of the traditional motor brushless DC pump. Moreover, it can be fully submerged and completely waterproof, effectively improving the service life and performance of the pump.
Application of magnetic pump
It can be used for computer water cooling system, solar fountain, desk fountain, handicraft, coffee machine, water dispenser, tea maker, wine pouring device, soilless cultivation, shower, women’s washer, tooth washer, water heater pressurization, water heating mattress, hot water circulation, swimming pool water circulation filtration, foot washing, surfing massage basin, surfing massage bathtub, automobile cooling circulation system, oiler, humidifier, airAdjusting machines, washing machines, medical devices, cooling systems, sanitary products.
Selection Guide of Magnetic Pump
Based on the current status of domestic magnetic pump production and the development of magnetic materials and sliding bearings, the following steps can be referred to when selecting magnetic pumps to ensure project quality.

For the pump with power less than 10KW, the use of magnetic pump can ensure the use effect.
When the shaft power of the pump is greater than 10KW or the medium temperature is higher than 100 ℃, the domestic magnetic pump shall be carefully selected, and the magnetic steel material, bearing data structure, etc. shall be limited. If necessary, the mask pump shall be selected.
At present, domestic magnetic pump manufacturers are generally small and medium-sized, and the means of development and research are relatively weak. For pumps beyond the range of product parameters, it is generally not appropriate to entrust manufacturers to develop or research, so as to ensure the quality and progress of the project.
The quality of the magnetic steel data is related to the life, reliability and price of the pump. When ordering, the magnetic steel data, the supplier and its performance indicators should be clear. The data and life of the sliding bearing should also be clear.

Maintenance of magnetic pump
1. Startup and operation

a. Clean the sundries around the equipment that affect the safety of equipment and operators.
b. Before starting, fill the pump with liquid to be delivered (if the pump is sucking), open the inlet valve, close the outlet gate valve, and connect the power supply.
c. Connect the power supply and check whether the rotation direction of the pump is correct.
d. The unit shall be put into trial operation for 3-6 minutes, and can be put into operation if there is no abnormal phenomenon.
f. During the first start after long-term shutdown or pump maintenance, remove the fan cover of the motor and manually crank it, check whether the magnetic pump rotates flexibly, and install the fan cover after confirming that there is no problem.

2. Normal shutdown
Close the gate valve at the outlet first, and then cut off the power supply.
3. Emergency stop
Stop the motor immediately, and then close the outlet valve and inlet valve.
4. Repair and maintenance
Check the pump and motor regularly and replace the vulnerable parts.
When the pump is shut down for a long time, clean the inner flow passage of the pump and cut off the power supply.
No idling is allowed.
5. Precautions during operation

a. Pay attention to the pressure difference before and after the screening procedure at the suction end. When the pressure difference increases, it means that there is foreign matter blocking the screening procedure. Stop the pump to clean the strainer.
b. Whether the discharge volume and pressure meet the specified value;
c. Whether there is abnormal sound and vibration. If there is abnormal sound or vibration, it generally indicates cavitation or excessive wear of bearings.
e. Whether there is cavitation in the pump: open the outlet valve of the pump, when the flow reaches a certain amount, a sound and vibration will suddenly occur, and then continue to open the valve. If the flow is still not increased, it means there is cavitation. When there is cavitation, exhaust operation should be carried out. Note: the magnetic pump can never operate under the cavitation state, and if it continues to operate under this state, it will cause early wear of the bearing.
f. Whether the current value of the motor exceeds the rated current.

g. Check whether the temperature of each part of the pump is abnormally overheated.
h. The pressure of nitrogen pressure stabilizing system shall be kept within the specified range.
Matters needing attention
1. Prevent particles from entering
1) Ferromagnetic impurities and particles are not allowed to enter the magnetic transmission and bearing friction pairs.

(2) After conveying the media easy to crystallize or precipitate, it is necessary to wash them in time (after stopping the pump, fill the pump cavity with clean water, and drain it after 1min of operation) to ensure the service life of the sliding bearing.
(3) When conveying media containing solid particles, filter at the inlet of pump flow pipe.

2. Prevent demagnetization

(1) The magnetic torque shall not be too small.
(2) It shall operate under the specified temperature conditions, and the medium temperature is strictly prohibited to exceed the standard. A platinum resistance temperature sensor can be installed on the outer surface of the magnetic pump isolation sleeve to detect the temperature rise in the annulus area, so as to alarm or shut down when the temperature exceeds the limit.

3. Prevent dry friction
1) Idling is strictly prohibited.

(2) It is strictly prohibited to evacuate the medium.
(3) When the outlet valve is closed, the continuous operation time of the pump shall not exceed 2min to prevent the magnetic actuator from overheating and failure.
(4) Not available in pressurized systems.

Troubleshooting of magnetic pump
1. Broken pump shaft
The pump shaft of the magnetic pump adopts 99% alumina porcelain.
2. The magnetic pump bearing is damaged.
The bearing of the magnetic pump adopts high-density carbon, which will cause damage to the bearing in case of water cut off or impurities in the pump. If the coaxiality requirements between the inner and outer magnetic rotors of the cylindrical coupling are not guaranteed, the service life of the bearing will also be directly affected.
3. The magnetic pump cannot pump liquid
The magnetic pump cannot pump out liquid, which is the most common fault of the pump, and there are many reasons for it. First, check whether there is air leakage in the suction pipe of the pump, whether the air in the suction pipe is discharged, whether the liquid filled in the pump is sufficient, whether there are sundries in the suction pipe, and whether the pump is reversed (especially after the replacement of the motor or the maintenance of the power supply line) Pay attention to whether the pump suction height is too high.
If the problem cannot be solved through the above inspection, the magnetic pump can be disassembled for inspection.
It is worth noting that the pump has been repaired several times and no problem can be found. Pay attention to whether the magnetic coupling works normally.
4. The magnetic pump head is insufficient.
The reasons for this failure are: there is air in the conveying medium, the impeller is damaged, the speed is not enough, the proportion of the conveying liquid is too large, and the flow is too large.
5. The magnetic pump has insufficient flow.
The main reasons for insufficient flow are: damaged impeller, insufficient speed, too high lift, sundries in the pipe, etc.

7. Pipeline pump

What is a pipeline pump?

Pipeline pump is a kind of single suction single-stage or multi-stage centrifugal pump, which is a vertical structure. Because its inlet and outlet are in the same straight line, and the inlet and outlet diameters are the same, it resembles a section of pipeline, and can be installed at any position of the pipeline, so it is called pipeline pump (also called booster pump). Structural features: it is a single suction single-stage centrifugal pump, with the same inlet and outlet on the same straight line and perpendicular to the shaft centerline. It is a vertical pump.
Working principle of pipeline pump
The reason why the pipeline pump can send water out is because of the centrifugal force. Before the pump works, the pump body and the inlet pipe must be filled with water to form a vacuum state. When the impeller rotates rapidly, the blades make the water rotate quickly. The rotating water flies away from the impeller under the centrifugal force. After the water in the pump is thrown out, the central part of the impeller forms a vacuum area. The water in the water source is at atmospheric pressureUnder the action of force (or water pressure), it is pressed into the water inlet pipe through the pipe network.
Application of pipeline pump
The pipeline pump can be used to eliminate the pressure difference (see the actual head, and the pipeline friction loss (product pipeline) caused by transporting crude oil from the origin or oil depot to the refinery and refined oil products such as gasoline, kerosene, fuel oil or diesel oil to the place of use through pipelines.
The pipeline pump can also be used as alkali washing liquid pump or salt rock cavern flushing and filling pump in gas storage field. The pipeline pump without balance device shall be used in these applications.
Classification of pipeline pumps
The main series of pipeline pumps are multi-stage pipeline pumps, vertical pipeline pumps, vertical high-temperature centrifugal pumps, vertical pipeline chemical pumps, vertical pipeline oil pumps, vertical stainless steel explosion-proof chemical centrifugal pumps.
Selection guide of pipeline pump

1. The multi-stage pipeline pump is used to transport clean water and other liquids with physical and chemical properties similar to clean water. It is suitable for industrial and urban water supply and drainage, pressurized water supply for commercial buildings, garden sprinkler irrigation, fire pressurization, long-distance transmission, HVAC refrigeration cycle, bath space and other cold and warm water cycle pressurization and equipment supporting, with the service temperature of T<80 ℃.
2. The vertical pipeline pump is suitable for the pressurized circulation of high-temperature hot water for boilers in metallurgy, chemical industry, textile, wood processing, paper making, hotels, bathrooms, hotels, and urban housing heating, with the operating temperature below 120 ℃.
3. The vertical high-temperature centrifugal pump is widely used in: energy, metallurgy, chemical industry, textile, paper making, as well as high-temperature hot water pressurization circulation transmission of boilers such as hotels, bathrooms, hotels, and pipeline pumps for urban housing heating circulation, with the operating temperature below 240 ℃.
4. The vertical pipeline chemical pump is used to transport corrosive liquids without solid particles and with viscosity similar to water. It is suitable for petroleum, chemical industry, metallurgy, power, paper making, food and pharmaceutical, synthetic fiber and other departments, and its operating temperature is – 20 ℃~120 ℃.
5. Vertical pipeline oil pump is used to transport gasoline, kerosene, diesel and other petroleum products, and the temperature of the conveyed medium is – 20 ℃~+120 ℃.
6. Vertical stainless steel explosion-proof chemical centrifugal pump is suitable for conveying flammable chemical liquids.

Maintenance of pipeline pump
Key points for quick maintenance of pipeline pump:
1) Every 500 hours of operation, loosen the screw plug on the seal seat, and use a syringe to draw out the residual oil in the cavity; fill the seal cavity with qualified 20 # mechanical oil to half the volume of the cavity (check method for proper amount of oil: run the oil pump, and the oil will not leak out): tighten the screw plug to prevent leakage.
2) If the mechanical noise of the motor is increased and the temperature rise at the bearing is abnormal, the lubrication condition of the motor bearing should be checked. If the grease is discolored or dirty, it should be replaced in time.
3) When oil leakage is found on the seal seat, loosen the screw plug on the seal seat and run the oil pump. When oil emerges and there is a smell of aviation oil, it can be determined that the mechanical seal is invalid. Stop using the pipeline pump to quickly replace the mechanical seal.
4) Methods for replacing failed mechanical seals:

(1) Prepare the workbench (ground) and disassembly tools for placing pump parts, and do not use them randomly to avoid damaging pump parts.
(2) Before disassembly, confirm that the motor is in maintenance status; unscrew the oil filling plug; use a suction pipe to suck out the lubricating oil in the seal seat cavity.
(3) Dismantle the split coupling: first unscrew the fixed socket head cap screws of the coupling, and then gently pull off half of the coupling from the shaft (be careful not to fall off). Use a box wrench to unscrew the pump shaft fastening bolt and block, let the impeller slowly sink to the pump body, remove the other half of the coupling, and remove the pump shaft retaining ring.
(4) Dismantle the seal seat: unscrew the seal seat compression nut, gently remove the seal seat (note: do not break the rubber oil seal on the seat) and clean it.
(5) Dismantle and clean the bearing pedestal: first loosen the bearing pedestal slightly, then jack up the bearing pedestal with the disassembly bolts, and remove it by lifting it down along the pump shaft. Clean the bearing and pedestal with jet fuel, dry them before installation, and apply a little 20 # machine oil for lubrication and protection.
(6) Disassembly of mechanical seal: Grasp the seal spring and lift it up along the pump shaft to disassemble it.
(7) Mechanical seal assembly: apply a layer of clean No. 20 lubricating oil on the mirror surface of the moving and stationary rings: apply lubricating oil on the guide bearing seat, first position the stationary ring gently and install it into the guide bearing seat; then apply lubricating oil on the pump shaft, gently install the moving ring part of the mechanical seal into the pump shaft, and gently push the seal ring by hand to ensure that it can expand and contract freely (pay attention to the anti rotation part surface of the moving and stationary rings to be assembled in place)。
(8) Install the seal seat: first install the rubber oil seal on the seal seat, then install the seal seat into the pump cover and press it on the bearing seat, and tighten the nuts.
(9) Install the coupling: first install the retaining ring on the motor shaft head, install a coupling, then install the stop in the pump shaft end and the coupling groove and tighten the bolts with a box wrench (lift the pump shaft 3-5 mm to provide mechanical seal prestress): Install the other half of the coupling and tighten the hexagon socket head cap screws. The correct inspection requirements for installing the coupling: the upper and lower clearances of the split coupling are even; manually rotate the coupling for several cycles to check whether it can rotate flexibly.
(10) Run in according to the key points of use to check whether the replacement of mechanical seal is correct and whether the pump unit operates normally.

Matters needing attention
Operation inspection: when the pipeline pump operates normally at power frequency (frequency conversion), it shall regularly check and record the readings of ammeter, voltmeter, inlet and outlet vacuum gauge, pressure gauge, flowmeter and other instruments of the pump set. Check whether the vibration, noise, temperature rise, etc. of the unit are normal. There shall be no obvious aviation oil leakage at the shaft seal.
There are always problems during the use of the machine, but good use and maintenance can ensure the best performance of the machine. In order to ensure normal oil supply, the normal use and rapid maintenance of the pipeline pump have become the top priority of the oil depot equipment management.
Troubleshooting of pipeline pump
1. Water leakage
Cause: The seal is damaged.
Troubleshooting: Replace the seal (shaft seal or O-ring).
2. Pump does not absorb water
Cause:
1. The water injected into the pipeline pump is not enough. 2. The suction pipeline system leaks air or the bottom valve leaks water. 3. The pipeline is deflated.
Troubleshooting:
1. Open the vent plug, refill water, exhaust the air in the pump, and close the vent plug. 2. Check all connection parts, reseal and repair the bottom valve. 3. Install correctly.
3. The pressure is expressed to the specified pressure but the water volume is insufficient.
Cause:
1. The resistance loss of outlet pipeline is large. 2. The output height exceeds the capacity of the pump.
Troubleshooting:
1. Shorten the outlet pipe or increase the pipe diameter. 2. Re purchase the appropriate water pump.
3. Water yield reduction
Cause:
1. Air invades the pump. 2. The radial clearance at the impeller mouth ring is too large, which makes the water in the pump backflow. 3. The foot valve or pipeline is partially blocked. 4. The motor terminal voltage is too low, causing the speed to drop.
Troubleshooting:
1. Check the air leakage part and seal it.

2. Replace worn impeller.

3. Stop the machine for inspection.

4. Stabilize the grid voltage.
5. The pump vibrates or has noise
Cause:
1. The unit is not firmly installed. 2. The suction pipe leaks or the submergence depth of the suction pipe orifice is not enough, so that air is sucked into the pump. 3. Impeller cavitation. 4. Deviation from operating conditions.
Troubleshooting:
1. The supporting part at the pump flange shall be reinforced. 2. Block the leak or lengthen the submergence depth of the suction pipe. 3. Lower the pump installation height or increase the suction pipe diameter or increase the inlet pressure, and replace the damaged impeller. 4. Adjust the pump to the high efficiency area (rated point) as far as possible to avoid the pump running at the high flow point.
6. Motor heating
Cause:
1. The ambient temperature is too high, and the motor has poor heat dissipation. 2. The motor load is too heavy. 3. The voltage is too high or too low or the phase is missing. 4. Water ingress into the motor.
Troubleshooting:
1. Improve the working environment of the pump, check whether the fan blades are normal and whether the ventilation duct is blocked. 2. If the pump is stuck, shut down for maintenance; or the bearing is damaged, replace the bearing; or the pump runs at a high flow rate, adjust the pump to run at the rated point and in the high efficiency area of the pump. 3. Stabilize the power supply voltage. 4. Disassemble the machine and dry it for maintenance to prevent water from entering the motor from the shaft hole gap or junction box.

8. Pressure test pump

What is a pressure test pump?

The pressure test pump is a kind of testing equipment specially used for various pressure vessels, pipes, valves, boilers, steel cylinders, fire-fighting equipment, etc. to conduct hydrostatic tests and obtain high-pressure liquids in the laboratory.
Working principle of magnetic pump
Its function is to transfer the power machine (such as motor and internal combustion engine)The mechanical energy of is converted into the pressure energy of the liquid. Working principle: The cam is driven by the motor to rotate. When the cam pushes the plunger upward, the sealing volume formed by the plunger and the cylinder body decreases, and the oil is squeezed out of the sealing volume and discharged to the required place through the one-way valve. When the cam rotates to the falling part of the curve, the spring forces the plunger downward to form a certain vacuum degree, and the oil tank Under the action of atmospheric pressure, the oil in enters the sealing volume. The cam makes the plunger continuously rise and fall, the sealing volume periodically decreases and increases, and the pump continuously absorbs and discharges oil.
Application of magnetic pump
The pressure test pump is mainly used for hydraulic test of various pressure bearing parts such as pressure vessels, valves, pipes, etc., and explosion test of gas cylinders, high-pressure hoses, etc.
Classification of magnetic pumps
There are three types of pressure test pumps: electric pressure test pump, manual pressure test pump and electric portable pressure test pump.
Selection Guide of Magnetic Pump
When selecting the type of pressure test pump, you must select the appropriate pressure test pump according to your actual pressure detection requirements.
1. The pressure test pump with matching pressure shall be selected according to the maximum working pressure. Since the pressure test pump itself has a 1.2 times safety factor, it is better that the maximum working pressure of the selected pressure test pump should not exceed 20% of the pressure detection point.
2. It is also critical to select the flow rate of the pressure test pump according to the volume of the pressure vessel. If there is no hard regulation on the pressure rise rate, it is generally appropriate for the pressure test pump to raise the pressure to the measured value within 3 minutes. If the volume is relatively small, the flow rate of the pressure test pump should be controlled within a certain range, followed by an external accumulator or buffer; that is because it is at a certain powerThe pressure and flow of the pressure test pump are inversely proportional. The higher the pressure, the greater the flow, and the larger the volume and purchase cost of the pressure test pump.
3. There are three pressure points for the pressure test pump to test the pressure of general pressure vessels, pipes, valves, etc.:

1) Normal working pressure.
2) The maximum working pressure (generally called insurance coefficient pressure) is usually 1.5 times of the working pressure.
3) The bursting pressure is usually more than 2.5 times of the working pressure. During the selection of the pressure test pump, some users have some selection errors due to their lack of knowledge of the technical parameters of the pressure test pump. Some believe that the higher the pressure of the pump, the higher the safety factor; some believe that the greater the pump flow, the faster the pressure rise.

If we do this, first, it may increase the purchase cost of equipment; second, the purchased equipment does not match the tested container, which will more or less affect the testing quality. Therefore, in the process of selecting the pressure test pump, we must select the pressure test pump suitable for our own testing according to the pressure and volume of the tested container. The above is only for reference when selecting the pressure test pump,The appropriate pressure test pump must be selected according to your actual pressure detection requirements.
Maintenance of magnetic pump

1. Before using the pressure test pump, check carefully whether the connections of all parts are tightened, whether the pressure gauge is normal, and whether the inlet and outlet pipes are installed properly. The working medium of this pump is clean water at 5~50 ° C, emulsion, or an oiler with kinematic viscosity<45mm2/s. It is prohibited to use dirty water with sediment and other pollutants.
2. To improve the efficiency of pressure test, first fill the tested container or equipment with water, and then connect the outlet pipe of the pressure test pump.
3. During the pressure test, if there is much air in the water, the water valve can be screwed to drain the air.
4. If any slight water mixing is found during the pressure test, the work shall be stopped immediately for inspection and repair. It is strictly prohibited to increase the pressure under the condition of water mixing.
5. After the pressure test is completed, loosen the water opening valve to reduce the pressure to avoid damage to the pressure gauge.
6. When the pressure test pump is not in use, the water in the pump should be drained and a small amount of oil should be sucked in to prevent corrosion.

Matters needing attention
Precautions for use of pressure test pump

1. Before using the pressure test pump, check carefully whether the connections of all parts are tightened, whether the pressure gauge is normal, and whether the inlet and outlet pipes are installed properly. The working medium of the pump is clean water at 5~50 ° C, emulsion, or the oiler with kinematic viscosity<45mm2/s. It is prohibited to use dirty water with sediment and other pollutants.
2. In order to improve the efficiency of pressure test, the tested container or equipment can be filled with water first, and then connected to the outlet pipe of the pressure test pump.
3. During the pressure test, if there is much air in the water, the water valve can be screwed to drain the air.
4. If any slight water mixing is found during the pressure test, the work shall be stopped immediately for inspection and repair. It is strictly prohibited to increase the pressure under the condition of water mixing.
5. After the pressure test, loosen the water opening valve to reduce the pressure to avoid damage to the pressure gauge.
6. When the pressure test pump is not in use, the water in the pump shall be drained and a small amount of engine oil shall be sucked in to prevent corrosion.

Troubleshooting of magnetic pump
In case of any failure during pressure test, the causes of failure other than the pump (leakage of components under test, pipeline system, etc.) shall be eliminated first, and then the pump failure shall be checked and eliminated.

9. Metering pump

What is a metering pump?

The metering pump can meet the requirements of various strict process flows, and the flow can be adjusted steplessly within the range of 0-100% to transport liquids (especially corrosive liquids)A special positive displacement pump. The metering pump is also known as a constant displacement pump or a proportional pump. The metering pump is a reciprocating positive displacement pump, which is used for accurate metering. Generally, the stability accuracy of the metering pump is required to be no more than ± 1%. With the continuous development of modern industry towards automatic operation and remote automatic control, the metering pump has strong compatibility and regulates the medium (liquid)The extensive advantages are particularly prominent.
Working principle of metering pump
Working principle of metering pump: the motor drives the worm through the coupling and decelerates through the worm gear to make the spindle and eccentric wheel rotate, and the eccentric wheel drives the sliding adjustment seat of the bow shaped connecting rod to reciprocate. When the plunger moves backward to the dead center, a vacuum gradually forms in the pump chamber, and the suction valve opens to suck in liquid; when the plunger moves forward to the dead center, the suction valve closes and the discharge valve opensOn, the liquid is discharged when the plunger moves further. The continuous pressure and quantitative discharge liquid is formed during the reciprocating operation of the pump.
Application of metering pump
It is suitable for occasions with high pressure, low pressure, strong (weak) corrosivity and high metering accuracy;
For example, it is used for adding additives and exploiting gas in the petroleum industry; it is used for adding proportional chemical media in the chemical industry; it is used for industrial water treatment in environmental protection; it is used for boiler in thermal power plant as dosing pump for purified water treatment, etc.

Applicable industries: petroleum industry, gas mining, chemical industry, oil refining, thermal power plant, industrial and mining [boiler], food, pharmacy, scientific research, printing and dyeing, paper making, environmental protection, especially water treatment industry, etc.
Regulating form of metering pump: manual regulation, electric regulation, frequency conversion regulation.
Others: explosion-proof motors can be configured, and spare parts, wearing parts, tools, etc. can be provided free of charge. They can be consigned to the user for commissioning.

Classification of metering pumps
The metering pump is based on the overflow part: plunger, piston, mechanical diaphragm and hydraulic diaphragm.

According to the drive pipe: motor drive and electromagnetic drive.
According to the working mode: reciprocating, rotary and gear type.
According to pump characteristics: extra large base, large base, medium base, small base and microcomputer base.
Other classified pipelines: electric control, pneumatic control, thermal insulation, heating, high viscosity, etc。

Selection guide of metering pump

1、 Determine the pressure: the rated pressure of the extracted metering pump should be slightly higher than the actual maximum pressure required, generally 10-20% higher. Do not choose too high, because too high pressure will waste energy, and investment and operation costs of new equipment.
2、 Determine the flow: the flow of the metering pump extracted should be equal to or slightly greater than the flow required by the process. The range of use of the metering pump flow should be 30-100% of the rated flow range of the metering pump. At this time, the repeated reproduction accuracy of the metering pump is high. Considering the economy and practicality, it is recommended that the actual required flow of the metering pump should be 70-90% of the rated flow of the metering pump.
3、 Determination of pump head (hydraulic end) material: after the specific model and specification of the metering pump are determined, the material of the flow passage part is selected according to the properties of the flow passage medium. This step is very important. If the selection is not correct, it will cause medium corrosion, damage to the flow passage parts or medium leakage, pollution of the system, etc. In serious cases, it may also cause major accidents.
Other aspects: when selecting the metering pump, it is also necessary to consider the accuracy level of the metering pump required. The higher the accuracy level, the greater the input. Generally, the working temperature of the metering pump is – 30-100 ℃, and the working temperature range of the special metering pump is wider (for example, the delivery temperature of the high-temperature liquid metering pump with insulation jacket can reach 500 ℃)The particle size of the medium is required to be less than 0.1mm. For the medium larger than 0.1mm, the flow structure of the pump can be specifically changed to meet the needs. The viscosity of the medium should generally be 0-1000mm/s, and the special metering pump can reach 6000mm2/s. The flow of the mechanical diaphragm metering pump is the maximum flow measured under the calibrated rated pressure(When delivering clean water at room temperature), if the pressure drops, the output flow will be higher than the calibrated flow.

Maintenance of metering pump
When using the metering pump, it is necessary to regularly check whether there is any leakage at the connection between the pipeline and the valve, and the valve should be cleaned every three months to avoid blocking (the cleaning time can be adjusted according to the agent properties, such as the use of high crystallinity agents, at least once a month). When the metering pump has not been operating for a long time, it should also be cleaned before use.
Cleaning steps of metering pump:

(1) First hit clean water for about 10 minutes, then hit empty for about 5 minutes, and then make sure that the water in the pipe is discharged before starting the disassembly to reduce the danger.
(2) Turn off the power supply of the metering pump and remove all valves (still be careful of the residual agent and water during disassembly to avoid injury or damage caused by splashing on the power supply and other related equipment).
(3) Flush the valve and its internal parts with clean water.
(4) Check whether the parts are damaged, deformed, cracked, etc., and replace them if any.
(5) Reinstall all valves as they are.
(6) Apply clean water for 5 minutes for testing (if there is crystallization, apply crystal diluent for about 10 minutes, and then apply clean water for about 5 minutes).

Reminder:

(1) Wear protective clothing (goggles, gloves, etc.) when cleaning.
(2) The valves of the metering pump are all made of plastic. Tools shall be avoided during disassembly and assembly to avoid damage to the parts.

Matters needing attention
Precautions for installation of metering pump

1. The outlet is higher than the inlet to avoid siphonage.
2. The pump head and injection valve shall be installed vertically.
3. The attached pipe fittings can be tightened by hand, do not use tools; do not use raw tape at the thread.
4. The power supply voltage is stable and grounded.
5. The installation environment is clean, spacious and well ventilated.

Troubleshooting of metering pump
1. Abnormal liquid suction of metering pump
Rotate to 100% of the stroke length. In this way, the whole set of components can rotate to the back plate leakage discharge hole and align with the bottom end of the pump. Adjust the hydraulic end and diaphragm to the proper position during the operation of the pump.
For the response time, the pulse duration may not be long enough. Compared with the standard pulse width of 80msec, the pulse width expansion of the flow camera can be started, and the new pulse width is 300msec. Start the smart switch, remove the cover fixing the circuit board, and remove the jumper X-1. This enables the expansion function, allowing more time before the fault indication.
The metering pump is installed with a self venting pump head, which adopts self filling suction. Keep the suction pipeline as short as possible.
2. Dismantle and replace the diaphragm of metering pump
When removing old diaphragms, trouble is often encountered. Here are some additional suggestions on how to remove old diaphragms.

1) After the pump head is loose, before removing the pump head, adjust the stroke length to 10%. This can ensure that the electromagnetic shaft has enough pressure to keep its connection stable, so that the diaphragm can be unscrewed.
2) Pull the hydraulic end outward to disengage the screw from the socket. Hold the liquid end and rotate it counterclockwise. With slight resistance, unscrew the diaphragm.
3) The metered chemicals may crystallize at the hydraulic end, causing the ball and seat of the one-way valve to fail to work properly.
4) There may be gas leakage at the suction end of the metering pump. The connection piece at the suction side of the hydraulic end may be lack of O-ring or the connection of the suction valve may be loose.

3. Flow monitoring is used to measure a medium with high viscosity, and flow fault indication signal is received during liquid introduction. What can be done to solve this problem?
Move the hydraulic end by loosening the four pump head screws. The length of the rotation stroke reaches 10%, grasp the hydraulic end, and then slide out from the screw hole, so the screws do not contact them, but still hold the back plate and diaphragm. Then rotate the part counterclockwise, with a slight resistance, the diaphragm will loosen from the electromagnetic shaft. If the diaphragm is not loose, use some on the contact surface of the diaphragm and the electromagnetic shaftLubricating oil. After a few minutes, gently tap the diaphragm with a small plastic hammer. Then carry out again as described above
4. How to prevent the stroke positioning motor of metering pump from burning out?

1) Remove the 4 screws fixing the pump head. The screws are located on the back of the metering pump.
2) Check whether the drain pipe is installed and the drain valve is closed. The drain valve needs to be opened during the liquid introduction phase of the metering pump. Note: not all metering pumps have drain valves.
3) After the diaphragm is installed and the backplate leakage discharge hole is placed in a vertical position, install the pump head. Ensure that the suction valve is aligned with the leakage discharge hole, and the screw at the hydraulic end is aligned with the corresponding four holes.

5. Is the flow of the hydraulic metering pump smaller or inaccurate?

1) Unscrew the bleeder valve in the three valves.
2) Make up oil fully through the oil make-up valve.

10. Mask pump

What is a mask pump?

The drive of ordinary centrifugal pump is to connect the impeller shaft of the pump with the electric shaft through the coupling, so that the impeller and the motor can rotate together to work. The mask pump is an unsealed pump. Both the pump and the drive motor are sealed in a pressure vessel filled with pumped media. This pressure vessel has only a static seal, and a wire group provides a rotating magnetic field and drives the rotor. This junctionThe rotary shaft sealing device of traditional centrifugal pump is canceled, so it can achieve complete leak free.
Operating principle of mask pump
Mask pump is a kind of sealless pump. Both the pump and the drive motor are sealed in a pressure vessel filled with pumped medium. This pressure vessel is only statically sealed, and a wire group provides a rotating magnetic field and drives the rotor. This structure eliminates the rotating shaft sealing device of traditional centrifugal pump, so it can achieve complete leak free.
The mask pump connects the pump and the motor. The rotor of the motor and the impeller of the pump are fixed on the same shaft. The mask sleeve is used to separate the rotor and stator of the motor. The rotor operates in the conveyed medium, and its power is transmitted to the rotor through the stator magnetic field.
Application of mask pump
1. Civil

Ground source heat pump air-conditioning circulating water system;
Lithium bromide air conditioning unit air conditioning pump, transformer oil pump, motorcycle pump, etc;
Heating and circulating water system;
Fire water pressurization system;
Tap water pressurization system.

2. Industrial and military aerospace

Transportation of toxic and harmful liquids for chemical and pharmaceutical industries;
Fuel filling before launch of space rocket;
Nuclear grade mask electric pump for nuclear power plant.

Classification of mask pumps
Mask pumps can be divided into the following types according to the temperature, pressure, presence or absence of particles, viscosity and other different requirements of the liquid to be delivered:
1、 Basic type (standard type)
The temperature of the conveying medium shall not exceed 120 ℃, and the lift shall not exceed 100m. All other types of mask pumps are variants and improvements on the basis of the basic type.
2、 Reverse circulation type
For this type of mask pump, the liquid flow direction for bearing lubrication, cooling and motor cooling is exactly opposite to the basic type.
The main feature of the reverse circulation pump is that it is not easy to produce cavitation, and it is suitable for conveying liquid that is easy to vaporize. Sometimes it is also called easy to vaporize.
3、 High temperature type
The temperature of the transmission medium can be as high as 450 ℃. Usually, a cooling water jacket is added outside the mask motor and a cooling sleeve is added to the external circulating pipe to cool the high-temperature circulating liquid to reduce the temperature of the motor and the bearing. In the case of low power, some manufacturers do not use the coolant, but set the cooling fins outside the motor and use special windings to adjust the working conditions. The operating temperature generally cannot exceed 400℃。
4、 High melting point type
Jackets are provided at the hydraulic end and motor side of the pump. Steam or liquid at a certain temperature can be introduced into the jacket to prevent crystallization of high melting point liquid. The external circulation pipe of the pump should also be equipped with thermal insulation (heating) jackets.
5、 High pressure type
The housing of the mask pump is a high pressure vessel, which enables the pump to withstand high system pressure. In order to support the mask sleeve under internal high pressure, the stator coil itself can be used to withstand pressure. It can also be used as a mask pump operating under high temperature and pressure.
6、 Self priming type
The suction inlet of the pump is much higher than the center of the impeller. After the pump is stopped, when there is no liquid in the suction pipeline, the impeller and the enlarged pump chamber are always full of liquid. When the pump is restarted, the pump can work without filling water. Self priming pump is especially suitable for extracting liquid from underground containers.
In addition, according to different methods, it can also be divided into submerged type, slurry type, high-pressure pipeline type and various types of mask pumps specially used for ships, nuclear power plants and absorption refrigeration devices. It can also be divided into vertical type, horizontal type, online type, single-stage, multi-stage and other different types.
Selection guide of mask pump
Precautions for mask pump selection:
The general mask pump uses some of the liquid delivered to cool the motor, and the annular gap is very small, so the delivered liquid must be clean. For transporting a variety of liquid mixtures, if they produce sediment, coking or colloidal substances, the mask pump (non slurry type) selected at this time may block the mask gap, affect the cooling and lubrication of the pump, and cause burning of graphite bearings and the motor.
The mask pump generally has circulating cooling pipes. When the ambient temperature is lower than the freezing point of the pumped liquid, anti freezing measures such as accompanying pipes should be taken to ensure that the pump can be started easily.
In addition, when starting the mask pump, the opening sequence of the outlet valve and inlet valve should be strictly observed. When stopping the pump, the outlet valve should be turned down first. When the pump stops running, the inlet valve should be turned off first and then the outlet valve.
In short, the mask pump is completely leak free, which effectively avoids environmental pollution and material loss. As long as the model is correct and the operating conditions are not abnormal, there is almost no maintenance work under normal operation. The mask pump is an ideal pump for conveying flammable, explosive, corrosive and precious liquids.
Maintenance of mask pump
1. Mask pump commissioning link
(1) Remove the foreign matters in the valves, pipelines and accessories in the pump.
(2) The air tightness test or hydraulic test shall be conducted for the electric pump at 1.1 times of the design pressure, and no leakage shall be checked.
(3) The cooling water shall be tested at 0.4MPa to check for cracks and leakage.
(4) Connect wires correctly according to the power and symbols in the junction box, and the root of the terminal must be fixed with insulating pipes.
(5) Remove all tools and sundries around the pump base.
(6) Check whether the bolts at each fastening part are fastened.
(7) Check whether the circulation pipeline and cooling system pipeline are unblocked
2. Working requirements for mask pump start-up
(1) Start the mask pump, and slowly open the outlet valve when the outlet pressure gauge reading reaches 1.2 times of the rated head.
(2) Determine the exhaust pressure and suction pressure, whether the indicated value, pressure and current of the TRG meter are normal, whether the operating sound and vibration meet the requirements, and whether the reverse circulation pipeline flow and bypass pipeline flow are unblocked and meet the requirements.
(3) When the discharge pressure is too small, the pump runs in reverse.
(4) The indication of the TRG meter in the red area (over range) indicates that the mask pump is in reverse operation and reconnected. Normal operation occurs when the indication in the green area is below 0.3.
(5) Check the pump for abnormal sound and vibration caused by foreign matters.
(6) After confirming that the mask pump operates normally, set the opening of outlet valve and bypass valve.
(7) Record the process flow, bypass flow and reverse circulation flow of the pump
3. Number of people and data to be checked after the mask pump is started?
(1) Check the pump inlet pressure, pump outlet pressure and differential pressure.
(2) Check whether the indicated value of mask pump TRG table is within the allowable range.
(3) Check whether the voltage and current meet the rated standard on the nameplate.
(4) Check for abnormal sound and vibration.
(5) Check the fastening parts for looseness and leakage.
(6) Check whether the circulation pipe and cooling system pipe are unblocked.
(7) Check whether the sealing parts are free from leakage, emitting, dripping and leakage.
4. Standard for daily maintenance of mask pump
(1) Check the electric pump for abnormal vibration.
(2) Check whether the indication of mask pump TRG table is within the allowable range.
(3) Check whether the liquid circulation pipeline and cooling system pipeline are unblocked and meet the design requirements.
(4) Check whether the pressure, flow and temperature of each part are normal on time and make records.
(5) Frequently check whether the bolts at the fastening parts are loose and the vibration caused by looseness.
(6) Check the sealing parts for leakage, emitting, dripping and leakage.
(7) The equipment label shall be clear, the surrounding environment shall be clean, and the equipment surface shall be free of dust, oil stain and sundries.
5. When the mask pump should be shut down urgently
(1) When the mask pump inlet is cut off.
(2) When the TRG meter indicates that the needle is in the red area.
(3) When there is an abnormal noise in the mask pump.
(4) When the mask pump vibrates violently.
(5) When the temperature of the mask pump cooling water jacket is too high or the liquid is cut off.
(6) When the motor overheats.
Matters needing attention
Safety precautions for mask pump maintenance
(1) Before maintenance, drain the medium in the pump, close the valves on the inlet and outlet pipelines, or close the valves on the circulating pipeline and cooling system, or block the blind plate to isolate it from the process system.
(2) Carefully and meticulously clean the pipeline, and handle the equipment maintenance procedures after the equipment and pipeline are analyzed and inspected to be qualified.
(3) Cut off the power supply and hang the sign with the words of “No Moving” or “Overhauled” before maintenance.
(4) Maintenance tools and parts disassembled, cleaned and replaced shall be placed in order in the specified place to achieve civilized maintenance.
Troubleshooting mask pump
Common faults and treatment of mask pump
1. Damaged graphite bearing
Cause: cavitation, shifting between shafts, graphite cracking. Treatment: switch the pump and replace the bearing.
2. Pump fails to start
Cause: the medium is crystallized or the temperature is low and viscous. Treatment: switch the pump to increase the pump body temperature.
3. Overheating of pump body
Cause: cavitation or cooling water interruption. Treatment: find out the cause and eliminate cavitation; restore cooling water.
4. Vibration or noise
Cause: cavitation or bearing wear. Treatment: find out the cause and eliminate cavitation; switch the pump to replace the bearing.
5. Low outlet pressure
Cause: cavitation, damaged impeller, and blocked inlet with impurities.

11. Booster pump

What is a booster pump?

Booster pump, as its name implies, is a pump used to pressurize water heaters, high buildings with low water pressure, saunas, saunas, etc., the top floor of apartments with insufficient water pressure, solar automatic pressurization, reverse osmosis water purifier pressurization, etc.
Operating principle of booster pump
First fill the booster pump with liquid, and then start the centrifugal pump. The impeller rotates rapidly. The blade of the impeller drives the liquid to rotate. When the liquid rotates, it flows to the outer edge of the impeller by inertia. At the same time, the impeller absorbs liquid from the suction chamber. In this process, the liquid in the impeller flows around the blade. During the flow around movement, the liquid acts on the blade with a lift force, which in turn is greater than that of the bladeA small, equal and opposite force is applied to the liquid. This force works on the liquid, making the liquid get energy and flow out of the impeller. At this time, the kinetic energy and pressure energy of the liquid increase.
The working principle of the gas-liquid booster pump is similar to that of the pressure booster. A very low pressure is applied to the large diameter air driven piston. When this pressure acts on a small area piston, a high pressure is generated. Through a two bit five vent control reversing valve, the booster pump can achieve continuous operation. The high-pressure plunger controlled by the one-way valve continuously discharges the liquid, and the outlet pressure of the booster pumpThe size is related to the air driving pressure. When the pressure between the driving part and the output liquid part reaches balance, the booster pump will stop running and no more air will be consumed. When the output pressure drops or the air driving pressure increases, the booster pump will automatically start running until the pressure balance is reached again, and then it will stop automatically. The single pneumatic non-equilibrium gas distribution valve is used to realize the automatic pumpReciprocating motion, the air drive part of the pump body is made of aluminum alloy. The liquid receiving part is made of carbon steel or stainless steel according to the different media. Generally, the pump has two inlets: air inlet and air exhaust. The one that can produce air pressure lower than normal pressure (i.e. atmospheric pressure) at the air inlet is called “negative pressure”; the one that can produce air pressure higher than normal pressure at the exhaust outlet is called “positive pressure”For example, the vacuum pump is often referred to as the negative pressure pump, and the booster pump is the positive pressure pump. The positive pressure pump is very different from the negative pressure pump. For example, the flow direction of the gas, the negative pressure pump is the external gas that is sucked into the air extraction nozzle; the positive pressure is ejected from the air exhaust nozzle; for example, the pressure is high or low.
Application of booster pump
Booster pumps are mainly used for water heater pressurization, high building low water pressure, sauna, sauna and other pressurization, the pressurization of insufficient water pressure on the top floor of the apartment, solar automatic pressurization, reverse osmosis water purifier pressurization and so on.
Booster pump purpose:

1. The water in the fishpond and fishing tank can be recycled. It can replenish fresh oxygen and avoid the generation of pollutants in the water.
2. The water pressure of tap water is insufficient to pressurize. The domestic water storage tank can greatly increase the water pressure and keep the water pressure stable.
3. The water tower of the apartment is pressurized. The water pressure of the uppermost apartment is insufficient because it is too close to the water tank. The water volume is too small or the water heater cannot be ignited.
4. The water heater is pressurized due to insufficient water pressure. To solve the problem of ignition failure caused by insufficient water pressure of the water heater, install a booster pump so that you can shower freely and take a comfortable bath.
5. The front end of the household water purifier is pressurized. With the continuous pollution of the water source, the tap water can no longer be drunk directly. People begin to carry out secondary treatment of household tap water. After the installation of the water purification equipment, the water pressure is significantly reduced, affecting normal use. It is particularly necessary to configure a booster pump in the front end.
6. Industrial equipment circulating boiler cooling. The equipment and devices cannot supply water when they are higher than the water level. Booster pumps are used and water flow check valves are equipped to enable the boiler, equipment, machinery, etc. to work continuously.

Classification of booster pump
Biogas type
Pneumatic booster pump is divided into gas-liquid booster pump and gas booster pump. The principle of booster pump is to use the low pressure of large area piston to generate high hydraulic pressure of small area piston. It is used in the industrial field for clamping the chuck of machine tool, charging the accumulator, charging the high-pressure bottle, and converting the pressure reducing gas into high pressure gas body. Booster pump can be used for any gas source whose pressure is not high enough, whether mechanical or testing device。
It is driven by gas, without electric arc and spark, and is completely used in places with flammable and explosive liquids or gases. No matter what causes the pressure drop in the pressure maintaining circuit, the booster pump will automatically start to supplement the leakage pressure and keep the circuit pressure constant. Compressed air, nitrogen, steam, gas, etc. can be used as the driving gas source of the pump.
Gas-liquid type
The gas drive part of the pump body is made of aluminum alloy until the pressure balance is reached again. The single air control non-equilibrium gas distribution valve is used to realize the automatic reciprocating motion of the pump. The liquid part is made of carbon steel or stainless steel according to the different media. The full set of seals of the pump are imported high-quality products, thus ensuring the performance of the gas-liquid booster pump.
Air type
The principle of the air booster pump is to use the low air pressure of the large area piston to generate the high hydraulic pressure of the small area piston. The air booster pump is used in the working environment where the pressure of the original air compression system needs to be increased, and can increase the air pressure of the working system to 2-5 times. Only the compressed air in the working system needs to be used as the air source. The pump is suitable for single air source pressurization. No power supply is required(It can be used in the field requiring explosion-proof). Within the pressure range of the pump, adjust the regulating valve to adjust the inlet pressure, and the output hydraulic pressure will be adjusted steplessly accordingly.
Chlorine type
The working pressure range of chlorine booster pump is large. Different types of pumps can be selected to obtain different pressure areas, and the input air pressure and output air pressure can be adjusted accordingly. It can reach extremely high pressure, 90Mpa gas. The flow range is wide, and only 0.1Kg air pressure for all types of pumps can work smoothly. At this time, the minimum flow can be obtained, and different flows can be obtained after adjusting the intake air volume. It is easy to control,It can meet the requirements from simple manual control to complete automatic control. Automatic restart, no matter what causes the pressure drop in the pressure maintaining circuit, will automatically restart, supplement the leakage pressure, and keep the circuit pressure constant. It is safe to operate, driven by gas, without electric arc and spark, and can be used in dangerous places.
Selection guide of booster pump
The reason for the name of booster pump is that it is a pump installed on the pipeline to pressurize, which is a special name for many pumps. Generally speaking, the pipeline booster pump refers to the pump installed on the pipeline to transport liquid, not limited to a certain type or form of pump, but can be vertical or horizontal, such as vertical multistage centrifugal pump, horizontal multistage centrifugal pump, vertical single-stage centrifugal pump, horizontal single-stage single-stage centrifugal pumpCentrifugal pumps, self-priming centrifugal pumps, etc. can all be called pipeline booster pumps. Generally speaking, pipeline booster pumps in the industry generally refer to pumps with pipeline structure, which can be directly installed in series like a pipeline.
Since booster pump is another name of pump, its selection also follows the selection of centrifugal pump, and the parameters to be noted are nothing more than flow, head, material, medium specific gravity, etc. The pump flow and head we usually refer to refer to are their rated flow and rated head, and the so-called rated flow and rated head refer to that the inlet and outlet of the pump are fully open and operate at power frequency (50Hz)In this case, the pumping capacity of the pump and the height to which the water can be pumped. The rated head corresponding to the rated flow of the pump is called the best working point of the pump. This working point is the working point with the highest efficiency of the pump. Therefore, the pump with the best working point parameters should be selected as far as possible when selecting the pump, which can not only give play to the best potential of the pump, but also improve the service life of the pump.
Maintenance of booster pump
Maintenance of pipeline booster pump:
As far as possible, the pipeline booster pump should be placed in a well ventilated place for operation, so as to facilitate rapid heat dissipation and reduce the motor temperature. Otherwise, the motor will be easily burned out if it runs for a long time. In addition, before starting, the water storage in the pump body must be checked, otherwise, not only the self-priming performance will be affected, but also the shaft seal components will be easily burned out. Before starting the pipeline booster pump, some necessary checks should be made: pump shaftWhether the rotation of the pump is normal and whether there is jamming; whether the position of the impeller is normal; whether the cable and cable plug are broken, scratched and broken, etc. During operation, pay attention to the voltage change, which is generally controlled within ± 5% of the rated voltage. In addition, the position of the pipeline booster pump in the water is very important, and it should be selected as much as possible to be abundant in water, free of silt and waterThe place with good quality shall be suspended vertically in the water, and shall not be placed horizontally to avoid falling into the mud or being blocked by suspended substances at the pump inlet, which will lead to a sharp decrease in water output or even failure to pump water.
Once the pipeline booster pump has a fault, do not disassemble it by yourself. Because when you disassemble it by yourself, first, you do not know where the fault is, which leads to blind disassembly; second, there is no special tool, which often damages the original intact parts. The best way is to go to an experienced and standardized maintenance point for maintenance, and replace the “over age” in timeParts and some vulnerable parts. Under normal circumstances, the water pump should be repaired every six months to prevent “sick” work.
In the non use period, the pipeline booster pump should be lifted away from the water source in time and the accumulated water in the pump should be drained, especially in cold winter. Then it should be placed in a dry place. If possible, users can also apply grease to the key parts of the pump and add lubricating oil to the bearings to prevent rust corrosion of parts. In addition, the non use period of the pump is not the longer the better. If it is not used for a long time, not onlyExtremely rusty parts will also reduce the service life of booster pump.
Matters needing attention
During the operation of booster pump, the operator shall strictly abide by his/her post, strengthen inspection, find problems in time and deal with them in time. In general, the following matters shall be noted.

oneCheck whether various instruments work normally, such as ammeter, voltmeter, vacuum gauge, pressure gauge, etc. If the reading is too large or too small or the pointer jumps violently, the cause should be found out in time and eliminated. If the reading of the vacuum gauge rises suddenly, it may be that the water inlet is blocked or the water level in the water inlet pool drops, which increases the suction head; if the reading of the pressure gauge drops suddenly, the water inlet pipe may leak and suckAir intake or speed reduction.
twoWhen the pipeline booster pump is running, the tightness of the packing should be appropriate. The gland is too tight, and the packing box has too little water seepage, which can not play the role of water seal, lubrication, and cooling. It is easy to cause the packing to heat up and harden, accelerate the wear of the pump shaft and shaft sleeve, and increase the mechanical loss of the pump; the packing is too loose, and water seepage is too much, which causes a lot of water leakage, or makes air enter the pump, reducing the volume efficiency of the pumpIn general, the tightness of the packing should be about 20 drops of water per minute, which can be adjusted by the packing gland thread.
3. The temperature rise of the bearing should not exceed 30~40 ℃ generally, and the maximum temperature should not exceed 60~70 ℃. If the bearing temperature is too high, the lubrication will fail, the bearing pad will be burned or the rolling element will be broken, and even the shaft will be broken or the pump shaft will be seized by thermal expansion. If the temperature rise is too high, the machine should be stopped immediately to check the cause and eliminate it in time.
4. Prevent the inlet pipe orifice of the circulating booster pump from being submerged deep enough, which will cause a vortex near the inlet, allowing air to enter the pump. The floating objects in the trash rack and the inlet pool should be cleaned in time to avoid blocking the inlet pipe orifice. Both of the above will increase the inlet resistance, cause the inlet pressure to decrease, and even cause cavitation.
5. Pay attention to the oil ring, and make it rotate asynchronously with the pump shaft freely. Listen to whether the sound of the unit is normal at any time.
6. Close the outlet gate valve at the front of the parking line, and then close the valve on the vacuum gauge and pressure gauge, and wipe the water and oil off the surface of the pump and motor. In houses without heating equipment, consider that the water pump will not freeze after parking in winter.

Troubleshooting of booster pump
1. The water has stopped, but the pump is running
Cause: The water pipe leaks. The water flow switch is controlled by the flow of water. As long as there is a certain degree of water leakage, the pump will start to work. Treatment method: check the water pipe and stop the leakage.
2. The pump stops after running for a while, and runs again after a few seconds.
Solution: Just ask the maintenance worker to check the water pipe and stop the leakage.
3. If there is air in the water pipe, it is very likely to cause water return, which will keep the pump running.
Solution: In this case, only need to install a check valve, which can be purchased in hardware stores.
4. Whether water is supplied or not, as long as the small switch of the pump is turned to automatic mode, the pump will start.
There is a problem with the water flow switch, just replace it.

12. High pressure pump

What is a high-pressure pump?

The high-pressure pump is a device that provides high-pressure power for high-pressure rotary jet grouting mud. It is used to strengthen the foundation of buildings, highways, etc. It can also be used for high-pressure water jet assisted rock breaking and coal falling, underground hydraulic prop fluid supply, anchored with hydraulic expansion metal anchor bolts to pump high-pressure water, dredging and dredging of large underground pipelines.
Application of high-pressure pump
The high-pressure pump is used for strengthening the foundation of buildings, highways, etc., and also can be used for high-pressure water jet assisted rock breaking and coal falling, underground hydraulic prop fluid supply, anchored with hydraulic expansion metal anchor bolts to pump high-pressure water, dredging and dredging of large underground pipelines.
Classification of high-pressure pumps
High pressure pump can be divided into high-pressure plunger pump, high-pressure reciprocating pump, high-pressure electric pressure test pump and high-pressure cleaning pump according to the medium.
Selection guide of high-pressure pump
1. The selection of high-pressure pump shall consider factors such as simple structure, convenient operation, reliable operation, long service life, good performance, high efficiency, and the operation characteristics of the device; high interchangeability of parts, easy replacement, easy maintenance, low price, etc. Because the nature of the liquid pumped by the pump for process industry is different from that of ordinary pumps, and the process device requires long-term operation, it is also necessary to propose the following:Below.

(1) It is resistant to liquid corrosion and abrasion and has a long service life (corrosion-resistant pump or mud pump).
(2) Reliable sealing performance, especially for flammable, explosive, toxic and valuable media, it is required to control their leakage, or even completely leak free (mask pump or magnetic pump).
(3) It is required that the operation performance is stable, low noise, small vibration, and the operation period is not less than 8000h.
(4) It is suitable for the transportation of low-temperature or high-temperature media (low-temperature pump or heat flow pump).
(5) High suction performance is required, and NPSH is required. Small pumps (liquid hydrocarbon pumps, double suction centrifugal pumps); rotor pumps for transportation of high viscosity media; barrel pumps, high-speed partial flow pumps, and multistage pumps for low flow, high pressure, and high lift; metering pumps are required for metering accuracy.

Reciprocating pumps should be selected if the liquid viscosity is higher than 650mm2/s at the conveying temperature, the flow is small and the head is high; the gas content in the liquid is allowed to be slightly greater than 5% (volume)When the liquid needs to be measured accurately, the plunger metering pump can be used; when the liquid requirements are strict, the diaphragm metering pump can be used; for the liquid with poor lubrication performance, the gear pump and the three screw pump should not be used, but the reciprocating pump can be used; for the liquid with small flow, low temperature, and stable pressure requirements, the rotor pump or the twin screw pump should be used.
2. Determination of selected parameters
(1) Physical parameters of medium
The main physical parameters of the medium include density, viscosity, chemical composition, chemical corrosion performance, gas or solid (particle size) content, vapor pressure, etc.
(2) Process parameters
The physical properties of the medium under the transportation conditions will have a significant impact on the flow, head, power, necessary NPSH, structure, data, operation and use of the pump, which are important factors to be considered when selecting the pump.

①Flow. Considering the development and regulation of different requirements and other factors, the surplus capacity of the device and the coordination and balance with the capacity of each equipment in the device should be comprehensively considered when determining the pump flow. The flow of the pump given in the process design generally includes normal, maximum and minimum flow, and the maximum flow can be directly used when selecting the pump. If the maximum flow is not given, take 1% of the normal flow. 1x.
② Head. Also due to the above reasons, considering that the pressure drop calculation of the pipeline system (including equipment) in the process design is relatively complicated, and the calculation result may be slightly smaller, the head of the selected pump needs to have an appropriate margin, which is generally 1.05-1.1 times of the normal required head. The minimum level should be taken regardless of whether the medium level is higher or lower than the pump center.
③ Temperature. Determine the normal, maximum or minimum delivery temperature of the medium in the process (cryogenic pump).
④ The effective (systematic) cavitation allowance of the device should be greater than the necessary cavitation allowance of the pump. When the material at the inlet side is in a depressurized state or its operating temperature is close to the vaporization condition, the cavitation safety factor of the pump should be taken as a larger value. For example, at the bottom of the vacuum tower in the refinery, the cavitation safety factor of the pump should be taken as at least 1.3.
⑤ Operation time. Determine operation cycle and operation pipeline (continuous or gap).
⑥ Site conditions: ambient temperature, relative humidity, altitude, explosion-proof area and explosion-proof grade of the pump location.

Maintenance of high-pressure pump

1. The lubricating oil at the power end shall be injected as required.
2. For new pumps or overhauled ex factory pumps, the first oil change is 500 hours, and after that, change the lubricating oil every 3000 hours or according to the quality of lubricating oil.
3. Regularly check and correct that the relief pressure of the safety valve is 1.08-1.1 times of the rated working pressure.
4. Regularly check the accuracy of the pressure gauge.
5. Regularly check the tightness of the belt.
6. Replace the damaged vulnerable parts.
7. Adjust the clearance of each part, check and tighten each screw.
8. Pumps that need to be stopped for a long time (especially sewage pumps) should be washed with clean water, drained of the liquid in the pump, removed and cleaned all valves and coated with anti rust oil, and the whole pump should be protected against corrosion.
9. If you want to start the pump that has been parked for a long time, you should check and maintain the pump comprehensively, otherwise it cannot be started.
10. The overhaul period of high-pressure pump is temporarily 12000 hours.

Matters needing attention
Precautions for high-pressure pump:

1. The cleaning pump is a high pressure operation equipment, and it must not leave people during the operation, and frequently check the safety.
2. Pay close attention to the lubrication and operation of the unit. If there is leakage in connection, sealing, fastening bolts, etc., stop the machine in time for treatment.
3. The main operator and keyboard of the post must be notified to monitor the equipment in cleaning operation.
4. Must wear necessary labor protection appliances before work, and have detailed work records after work.
5. When using in winter, drain the water tank and the liquid inlet cavity after the pump is stopped to avoid freezing the water tank.

13. Rotor pump

What is a rotor pump?

Rotor pump refers to the pump that changes the working volume through the relative movement between the rotor and the pump body, thus increasing the energy of the liquid. Rotor pump is a rotary positive displacement pump with positive displacement, and its flow does not change with the back pressure. The main types of rotor pump include gear pump, screw pump, cam pump, sliding vane pump, rotary piston pump, hose pump, etc.
Rotor pump is also called colloid pump, cam pump, three lobe pump, universal delivery pump, etc. The rotor pump belongs to a positive displacement pump. It achieves the purpose of conveying fluid by means of the periodic transformation of multiple fixed volume delivery organizations in the working chamber. The mechanical energy of the motor is directly converted into the pressure energy of the conveying fluid through the pump. The flow of the pump only depends on the volume change value of the working chamber and its groupThe frequency of changes in weaving time, and (theoretically)It has nothing to do with the discharge pressure; the rotor pump actually rotates through a pair of synchronous rotors in the working process. The rotor is driven by a pair of synchronous gears in the box, and the rotor rotates synchronously in the opposite direction driven by the main and secondary shafts. This changes the volume of the pump, thus forming a high vacuum and discharge pressure. It is especially suitable for sanitary grade media, corrosive media and high viscosity mediaQuality transmission.
Operating principle of rotor pump
The rotor pump generates suction (vacuum degree) at the inlet during rotation by means of two rotors (2-4 teeth) rotating synchronously in reverse directionThe two rotors divide the rotor chamber into several small spaces and operate in the order of a → b → c → d. When the rotor chamber reaches position a, only chamber I is full of media; when the rotor chamber reaches position b, some media are enclosed in chamber B; when the rotor chamber reaches position C, media are also enclosed in chamber A; when the rotor chamber reaches position d, chamber A and chamber B are connected, and the media are transported to the outletLoop reciprocating, the medium (material) is continuously transported out.
Application of rotor pump

1. Food and beverage: dairy, latex, chocolate, syrup, cheese, wort, beer, soda。
2. Fruit concentrate: pudding, jam, jelly, tomato sauce。
3. Paste products: fat, grease, etc。
4. Cosmetics: face cream, detergent, hairstyle gel, perfume oil, etc。
5. Drugs: extract, emulsion, pill slurry, etc。
6. Chemical industry: dyes, fats, solvents, resins and polymers。

Classification of rotor pump
The main types of rotor pump include gear pump, screw pump, cam pump, sliding vane pump, rotary piston pump, hose pump, etc.
Selection guide of rotor pump
The selection basis of cam rotor pump should be considered from five aspects according to the process flow and water supply and drainage requirements, namely liquid delivery capacity, device lift, liquid property, pipeline layout and operating conditions。
Flow is one of the important performance data for pump selection, which is directly related to the production capacity and delivery capacity of the whole plant. When selecting a pump, the maximum flow is taken as the basis, taking into account the normal flow. When there is no maximum flow, 1.1 times of the normal flow is usually taken as the maximum flow.
The head required by the device system is another important performance data for pump selection, which is generally selected by enlarging the head after 5% – 10% allowance.
The liquid properties include the name of liquid medium, physical properties, chemical properties and other properties. The physical properties include temperature, density, viscosity, solid particle diameter and gas content in the medium. This involves the head of the system, effective NPSH and appropriate pump type.
The pipeline layout conditions of the device system refer to some data such as liquid feeding height, liquid feeding distance, liquid feeding direction, the lowest liquid level on the suction side, the highest liquid level on the discharge side, as well as pipe specifications and length, data, pipe fitting specifications, quantity, etc., in order to calculate the system head and check the NPSH.
There are many operating conditions, such as suction side pressure, discharge side vessel pressure, altitude, whether the ambient temperature is intermittent or continuous, and whether the pump position is fixed or movable.
Maintenance of rotor pump

(1) Check whether the rotor pump, pipeline and joint are loose. Rotate the rotor pump by hand to see whether it is flexible.
(2) Add bearing lubricating oil into the bearing body, observe that the oil level should be at the center line of the oil pointer, and the lubricating oil should be replaced or supplemented in time.
(3) Unscrew the water diversion plug of the rotor pump body, and inject water (or slurry).
(4) Close the gate valve, outlet pressure gauge and inlet vacuum gauge of the water outlet pipeline.
(5) Inch the motor to see if the rotation direction of the motor is correct.
(6) Start the motor. When the rotor pump runs normally, open the outlet pressure gauge and the inlet vacuum pump, and gradually open the gate valve as it shows the appropriate pressure. At the same time, check the motor load.
(7) Try to control the flow and head of the rotor pump within the range indicated on the label to ensure that the rotor pump operates at the highest efficiency point, so as to obtain the maximum energy saving effect.
(8) During the operation of the rotor pump, the bearing temperature shall not exceed the ambient temperature by 35C, and the maximum temperature shall not exceed 80C.
(9) If abnormal sound is found in the rotor pump, stop the pump immediately to check the cause.
(10) When the rotor pump is to be stopped, first close the gate valve and pressure gauge, and then stop the motor.
(11) In the first month of operation, the rotor pump shall change the lubricating oil after 100 hours, and then every 500 hours.
(12) Regularly adjust the packing gland to ensure that the leakage in the packing chamber is normal (it is better to leak in drops).
(13) Regularly check the wear condition of the shaft sleeve, and timely replace it if it is worn seriously.
(14) When the rotor pump is used in cold winter, it is necessary to unscrew the drain plug at the lower part of the pump body to drain off the medium after shutdown to prevent frost cracking.
(15) If the rotor pump is out of service for a long time, it is necessary to disassemble all the pumps, wipe off the moisture, coat the rotating parts and joints with grease, and install them properly.

Matters needing attention
1. Precautions before startup:
Check whether the oil quantity in the gearbox is normal and observe the transparent oil pointer. The oil quantity should be half of the oil pointer window. The lubricating oil should be replaced regularly. Generally, it should be replaced completely after 4000 hours of operation.
Before starting, open all inlet and outlet valves of the pipeline. When the medium flows into the cavity and there is no abnormality after rotating the pump by hand, inching can be started first. After confirming the rotation direction of the pump and the medium flow, the formal operation can be started. It is strictly prohibited to operate the pump without air. When the pump reaches the normal speed,
Observe the pressure quota of the pump.
When the pump installation position requires suction head, the inlet pipe and pump cavity of the pump shall be filled with materials.
When the process flow requires heating or cooling the medium, the heating or cooling device should be turned on before starting the pump, and the half of the heating energy should be turned on 10 minutes in advance before starting the pump.
The mechanical seal pump with cooling water is installed. The cooling water must be turned on before starting up, and ensure that there is no cutoff after starting up, or the mechanical seal will be damaged immediately.
2. Run
During the operation of the pump, attention should be paid to the motor power and pump operation. In case of any abnormality, the pump should be stopped to find out the cause.
The mechanical seal shall be free of leakage and heating.
For pumps with packing seals, 1~3 drops per minute is allowed. If the leakage rate increases, slightly press the material ring, without disassembly.
When the mechanical stepless transmission is used, the speed shall be gradually adjusted according to the digital display speed after starting. It is strictly prohibited to rotate the speed control disc when stopping, otherwise the stepless reducer will be damaged.
Manual frequency modulation and automatic control can be used for speed regulation by frequency converter.
Check the heating of the pump and motor frequently. When the pump is in the water cooling state, the bearing temperature rises to 40 ℃. When the pump is in the hot water insulation state, the bearing seat temperature is allowed to be 30 ℃ higher than the pump body temperature.
The valve of the inlet pipeline shall not be used to regulate the flow, so as to avoid the vibration of the pump caused by cavitation.
When the pump is running, it is forbidden to close all inlet and outlet valves.
3. Stop
Stop the pump, close the inlet and outlet valves, and discharge and clean the materials easy to condense.
After the pump has been out of service for a long time, the coupling should be turned by hand before starting. There is resistance in the hand, but it can rotate at will and the weight is uniform. Pay attention to identify whether there is friction sound and foreign matter in the pump.
When the pump and the reduction motor are reinstalled, the coaxiality of the pump shaft and the motor shaft should be checked, and the upper, lower, left and right pieces of the outer circle of the coupling should not exceed 0.1mm, otherwise the pump vibration will be caused and the service life of the main shaft will be affected.
Troubleshooting of rotor pump
Rotor pump is widely used in diesel engines for its small size, high speed, light weight, uniform fuel supply, low noise and other characteristics. However, it also has some shortcomings such as high precision, and the plug is easy to get stuck.
1. Common faults

(1) If no fuel is supplied, the fuel injector will not deliver fuel.
(2) The speed is unstable and the diesel engine shakes.
(3) There is air in the pump.
(4) The fuel supply is small.

2. Cause analysis
(1) Fuel injector does not inject fuel

① The injection pressure is too low: generally, the rotor pump is adjusted incorrectly or the orifice is blocked.
② Low oil supply pressure: in most cases, it is caused by serious wear of plunger or failure of oil delivery pump, wall plug of low-pressure oil circuit, no oil in oil tank, etc. The high-pressure oil pipe is too tight, and a torque is stored. When the diesel engine is working, the torque rebounds due to temperature rise or vibration, and the oil outlet valve loosens, which can also cause the oil pressure to decrease.

(2) Unstable speed

① In general, diesel engines with VE rotor pumps have relatively high speed. In case of abnormality, check whether the fuel injector is invalid, and then check whether the outlet valve seat of a cylinder is loose.
② Low idle speed may also cause the diesel engine to shake, air in the diesel or failure of the outlet valve may also cause unstable speed.

(3) Air in the pump

① There is air in the low-pressure oil circuit.
② The transmission shaft oil seal fails.

(4) Small fuel supply

① Improper adjustment: after the new plunger works for a period of time, the failure rate is relatively fast. Therefore, the fuel delivery of the fuel injection pump equipped with the new plunger should be increased by 0.5min/100 times during calibration.
② Plunger wear: the phenomenon of serious plunger wear is that there is no idle speed, and the high speed does not drop. To slow down, pull the shutdown handle, commonly known as false galloping.

If there is air in the rotor pump, check that the low-pressure oil circuit is normal, but the diesel engine has been working for a period of time there is always air. Several times, the car has traveled more than ten kilometers, and suddenly a stream of air has squeezed the oil in the pump clean. Then pump the oil and walk more than ten kilometers, this situation occurs again. It does not work to raise the fuel tank and add an electric fuel transfer pump. After analysis,It is believed that the gas in the crankcase is flushed from the oil seal of the fuel injection pump drive shaft, and it is normal after the oil seal is replaced.

14. Chemical pump

What is a chemical pump?

Chemical pumps are energy-saving pumps jointly designed nationwide. Their performance and technical requirements are designed according to the performance and dimensions specified in the international standard ISO2858. They can be divided into stainless steel chemical pumps, plastic chemical pumps, fluoroplastic chemical pumps, electric chemical pumps and pneumatic chemical pumps.
The advantages of chemical pumps are reasonable layout of the whole series of hydraulic performance, wide selection range of users, “back opening” structure, convenient maintenance, efficiency and suction head reaching the international advanced level.
Working principle of chemical pump
Negative pressure pump
Before starting the pump, the suction pipe and the pump must be full of liquid. After starting the pump, the impeller rotates at a high speed, and the liquid in it rotates with the blade. Under the action of centrifugal force, it flies away from the impeller and shoots out. The speed of the injected liquid in the diffusion chamber of the pump housing gradually slows down, and the pressure gradually increases, and then flows out from the pump outlet and the discharge pipe. At this time, the liquid is thrown to the circumference at the center of the bladeA vacuum low-pressure zone without air and liquid is formed around the liquid pool. Under the effect of atmospheric pressure on the pool surface, the liquid in the pool flows into the pump through the suction pipe. In this way, the liquid is continuously pumped up from the pool and continuously flows out of the discharge pipe.
Positive pressure pump
It mainly refers to the working principle of the submerged pump. Taking the submerged pump and the long shaft submerged pump in the gas station as an example, the submerged pump submerges the motor and the pump together into the tank bottom, and the motor drives the impeller to boost the pressure to push the medium to the ground target. The long shaft submerged pump connects the pump and the motor separately with a long shaft, and its working principle is to transport the medium under positive pressure. Therefore, the problem of air resistance and the impeller caused by the negative pressure transmission of the medium are solvedThe motor of the submersible pump is not above the liquid level, but below the liquid level. The motor is a submersible motor, which is connected with the pump wheel into a potential liquid. The main advantages of this design are: the pump bearing is only a few hundred millimeters, there is no long shaft, there is no swing problem, it runs smoothly, the sound is very low, and there is almost no wear.
Application of chemical pump
Scope of application of chemical pump:

Chemical pumps are suitable for extracting corrosive liquids from bottles, barrels, tanks, pools or other containers.
Chemical pumps have the advantages of stable and reliable performance, good sealing performance, beautiful appearance, convenient use and maintenance, etc. They play a great role in improving product quality, reducing leakage, emission, dripping, and leakage, preventing pollution, and improving the environment.
Chemical pumps are suitable for transporting corrosive media with temperature at various ℃ or media with high physical and chemical properties in chemical, petroleum, metallurgy, power station, food, pharmaceutical, synthetic fiber and other departments.
Chemical pump products mainly include: various glass fiber chemical pumps, corrosion resistant plastic pumps, high-temperature chemical pumps, standard chemical process pumps, magnetic drive pumps, etc.
Chemical pumps are used to pump clean water, containing abrasive substances harmful to ordinary pump body data, suspended substances corrosive to stainless steel materials, and non explosive substances; chemical pumps are also widely used for water supply; for heat supply, air conditioning, cooling, and circulation systems; for civil and industrial purposes; for fire protection; for irrigation; for daily and civil, industrial,Gardening and irrigation; used for rainwater storage projects; used for occasions where low noise is necessary; used for pressurization, suitable for conveying corrosive, explosive, granular water or liquid; suitable for pressurization of pipe networks.

Classification of chemical pumps
1. According to the different data of chemical pumps, their application fields are classified as follows:

1) Chemical pumps (made of stainless steel) are widely used in petroleum, chemical industry, metallurgy, synthetic fiber, pharmacy, food, synthetic fiber and other departments to transport alkaline corrosive media;
2) Chemical pump (fluoroplastic material) is used to transport any acidic and alkaline corrosive medium;
3) Chemical pump (cast iron material) is used for industrial and urban water supply and drainage, as well as farmland and orchard irrigation and drainage, to transport clean water or other liquids with physical and chemical properties similar to clean water.

2. According to the different uses of chemical pumps, their classifications are introduced in detail:

1) Process pumps: including feed pump, reflux pump, circulating pump, flushing pump, sewage pump, make-up pump, output pump, etc.
2) Utility pump: including boiler pump, cooling tower pump, fire pump, water source deep well pump, etc.
3) Auxiliary pumps: including lubricating oil pump, seal oil pump, hydraulic transmission pump, etc.
4) Pipeline delivery pump: pump for oil transmission pipeline, pump for loading and unloading vehicle, etc.

3. Classification according to working principle and structure:

1) Vane pump: When the pump shaft rotates, it drives various impeller blades to apply centrifugal force or axial force to the liquid, and transports the liquid to the pipeline or container, such as centrifugal pump, vortex pump, mixed flow pump and axial flow pump.
2) Positive displacement pump: a pump that uses the continuous change of the volume in the pump cylinder to deliver liquid, such as reciprocating pump, piston pump, gear pump, screw pump.
3) Other types of pumps: there are electromagnetic pumps that use electromagnetism to transport liquid conductors; pumps that use fluid energy to transport liquid, such as jet pumps, air lift devices, etc.

4. Classification by conveying medium:

1) Water pump: including clean water pump, boiler feed pump, condensate pump and hot water pump.
2) Corrosion resistant pump: including stainless steel pump, high silicon cast iron pump, ceramic acid resistant pump, impermeable graphite pump, hard rubber lined pump, rigid PVC pump, mask pump, diaphragm pump, titanium pump, etc.
3) Impurity pump: including slurry pump, sand pump, sewage pump, coal powder pump, ash pump, etc.
4) Oil pump: cold oil pump, hot oil pump, submersible pump, slurry pump, liquid hydrocarbon pump, etc.

5. Classification according to service conditions:

1) Large flow and micro flow pumps: the flow is 300m ³/min and 0. O1L/min respectively;
2) High temperature pump and low temperature pump: high temperature up to 500 ℃, low temperature down to – Z53 ℃;
3) High pressure pump and low pressure pump: high pressure up to 200MPa, vacuum degree 2.66-10.66kPa (20-80mmHg);
4) High speed pump and low speed pump: high speed up to 24000r/min, low speed 5-10r/min;
5) Accurate metering pump: the metering accuracy of flow reaches ± 0.3%;
6) High viscosity pump: viscosity up to several kilopascals (Pa · s).

Selection Guide of Chemical Pump
Material selection method of chemical pump
Corrosion has always been one of the most troublesome hazards of chemical equipment. A slight carelessness may damage the equipment, or even cause an accident or even disaster. According to relevant statistics, about 60% of the damage of chemical equipment is caused by corrosion. Therefore, when selecting chemical pumps, attention should first be paid to the scientificity of material selection. There is usually a misunderstanding that stainless steel is “universal data”No matter what medium and environmental conditions, it is very dangerous to hold stainless steel pumps. Here are the key points of chemical pump material selection for some common chemical media:

Sulfuric acid is one of the strong corrosive media. Sulfuric acid is an important industrial raw material with a wide range of uses. Sulfuric acid with different concentrations and temperatures has a large difference in data corrosion. For concentrated sulfuric acid with a concentration of more than 80% and a temperature of less than 80 ℃, carbon steel and cast iron have good corrosion resistance, but it is not suitable for high-speed sulfuric acid and is not suitable for data of pump valves; ordinary stainless steel such as 304 (0Cr18Ni9)316 (0Cr18Ni12Mo2Ti.
Most metal materials of hydrochloric acid are not resistant to hydrochloric acid corrosion (including various stainless steel materials), and molybdenum containing high silicon iron can only be used for hydrochloric acid below 50 ℃ and 30%. Contrary to metal materials, most non-metallic materials have good corrosion resistance to hydrochloric acid, so rubber lined pumps and plastic pumps (such as polypropylene, fluoroplastics, etc.) are the best choice for transporting hydrochloric acid.
Most common metals in nitric acid are rapidly corroded and destroyed in nitric acid. Stainless steel is the most widely used nitric acid resistance data. It has good corrosion resistance to all concentrations of nitric acid at room temperature. It is worth mentioning that stainless steel containing molybdenum (such as 316, 316L) is not only inferior to ordinary stainless steel in corrosion resistance to nitric acidstainless steel(e.g. 304, 321), sometimes even worse. For high-temperature nitric acid, titanium and titanium alloy data are usually used.
Acetic acid is one of the most corrosive substances in organic acids. Ordinary steel will be severely corroded in acetic acid of all concentrations and temperatures. Stainless steel is an excellent data for acetic acid resistance. Molybdenum containing 316 stainless steel can also be used for high temperature and dilute acetic acid steam. For high temperature and high concentration acetic acid or other corrosive media, high alloy stainless steel pump or fluoroplastic pump can be selected.
Alkali (sodium hydroxide)Steel is widely used in sodium hydroxide solution below 80 ℃ and within 30% concentration. Many factories still use ordinary steel at 100 ℃ and below 75%. Although the corrosion is increased, it is economical. Compared with cast iron, ordinary stainless steel has no obvious advantages in corrosion resistance to alkali liquor. As long as a small amount of iron is allowed to be mixed in the medium, stainless steel is not recommended. Titanium andTitanium alloy or high alloy stainless steel.
Ammonia (ammonia hydroxide) Most metals and nonmetals are slightly corroded in liquid ammonia and ammonia water (ammonia hydroxide), and only copper and copper alloys are not suitable for use.
The corrosion rate of salt water (seawater) ordinary steel in sodium chloride solution, seawater and salt water is not very high, so it is generally necessary to use paint for protection; various stainless steels also have a very low uniform corrosion rate, but may cause local corrosion due to chloride ions, and 316 stainless steel is usually preferred.
Common alcohol media of alcohols, ketones, esters and ethers include methanol, ethanol, ethylene glycol and propanol, ketones include acetone and butanone, esters include methyl ether and ethyl ester, ethers include methyl ether, ether and butyl ether, which are basically non corrosive, and common data are applicable. The specific selection should also be reasonable according to the properties and relevant requirements of the mediaSelection. In addition, it should be noted that ketones, esters and ethers are soluble to a variety of rubbers, so mistakes should be avoided when selecting sealing materials.

There are many other media that cannot be introduced here one by one. In short, we must not be arbitrary and blind when selecting materials. We should consult more relevant data or learn from mature experience.
Maintenance of chemical pump

Check whether the pump body, motor, pipeline and joint are loose. Rotate the pump by hand to see whether the pump is flexible.
Add bearing lubricating oil into the bearing body, observe that the oil level should be at the center line of the oil pointer, and the lubricating oil should be replaced or supplemented in time.
Unscrew the water diversion plug of the pump body, and inject water (or slurry).
Close the gate valve, outlet pressure gauge and inlet vacuum gauge of the water outlet pipeline.
Inch the motor to see if the rotation direction of the motor is correct.
Start the motor. When the pump runs normally, open the outlet pressure gauge and the inlet vacuum pump, and gradually open the gate valve and check the load of the motor after it shows proper pressure.
The flow and head of the pump shall be controlled within the range indicated on the label as far as possible to ensure that the pump operates at the highest efficiency point to obtain the maximum energy saving effect.
During the operation of chemical pump, the bearing temperature shall not exceed the ambient temperature by 35C, and the maximum temperature shall not exceed 80C.
If the pump has abnormal sound, stop the pump immediately to check the cause.
When the pump is to be stopped, first close the gate valve and pressure gauge, and then stop the motor.
In the first month of operation, the chemical pump shall change the lubricating oil after 100 hours, and then every 500 hours.
Regularly adjust the packing gland to ensure that the leakage in the packing chamber is normal (it is better to leak in drops).
Regularly check the wear condition of the shaft sleeve, and timely replace it if it is worn seriously.
When the chemical pump is used in cold winter, it is necessary to unscrew the drain plug at the lower part of the pump body to drain off the medium after shutdown to prevent frost cracking.
If the pump is out of service for a long time, it is necessary to disassemble all the pumps, wipe off the water, coat the rotating parts and joints with grease and install them properly.

Matters needing attention
1. Extended service life
In order to make the pump run normally, we should form a good habit of inspection and maintenance every day, which can avoid many troubles and also improve the work efficiency. Therefore, daily inspection and maintenance are very important and should not be ignored.
2. Environmental quality
Although the operating environment of pumps in our country is constantly improving, there are still some people who put pumps in places with poor environment. However, if they are placed in places with poor conditions, they should always clean them. In this case, people should always check and maintain them.
3. Daily inspection
In daily inspection, everyone should not only fully control the operation of chemical pumps and test the instruments, but also play a subjective role. Check whether the pressure, current, voltage, flow and temperature indicated by the instruments in each part are normal, whether there is deformation, deformation, leakage, blockage, etc.; listen to whether there is abnormal sound in each part, such as collision, breakingFriction sound and so on. At the same time, pay attention to whether the vibration of the chemical pump is very large.
4. Number of inspections
In order to ensure the working efficiency when using chemical pumps, people should check at least twice a day. Even pumps with a high degree of automation need to be checked regularly.

15. Vortex pump

What is a vortex pump?

The impeller of the vortex pump is a disc of equal thickness, and there are many radial small blades on both sides of its outer edge. There is an annular flow channel of equal section on the pump casing at the corresponding part of the blade. The entire flow channel is divided into suction and discharge sides by a tongue, which are connected with the suction and discharge pipes of the pump respectively. When the liquid in the pump rotates together with the impeller, a certain centrifugal force is generated, which is thrown outward into the annular flow channel in the pump casing, and forced to return under the restriction of the flow channel shape, and re enter the next blade channel from the blade root. Therefore, the movement trace of the liquid between the blade and the annular flow channel is a forward spiral for the stationary pump shell, and a backward spiral for the rotating impeller. The vortex pump is named for this kind of vortex movement of the liquid. The liquid can be continuousIt enters between the blades for many times to obtain energy until it is finally discharged from the discharge outlet. The vortex pump works somewhat like a multistage centrifugal pump, but the vortex pump does not have an energy conversion device like the volute or guide vane of a centrifugal pump. The vortex pump mainly transmits energy to the liquid through pipes that work continuously for many times, so it can generate higher pressure. In the process of energy transmission, due to the large amount of liquidSecondary impact, large energy loss, low pump efficiency, generally 20-50%. Vortex pump is only suitable for small flow (1-40 m3/h), high lift (up to 250 m)Such as fire pump, gasoline pump on aircraft refueling truck, small boiler feed pump, etc. The vortex pump can transport highly volatile and gaseous liquids, but it should not be used to transport thicker liquids with viscosity greater than 7 Pa · s and unclean liquids containing solid particles. The vortex pump features small flow, high head, self-priming function, and can be used to transport solids with viscosity less than 5 ° EBulk particles and liquid similar to water, such as gasoline, kerosene, alcohol, etc., can be used for small steam boiler water supplement, chemical, pharmaceutical, high-rise water supply and other purposes. The flow passage parts also have stainless steel and other materials that can be used to transport acid and alkali corrosive liquids. The temperature of transmission medium is – 20~+80 degrees. From the structure, it can be divided into: single-stage, two-stage, multi-stage, direct connection, etc.
Working principle of vortex pump
The impeller of the vortex pump is a disc of equal thickness, and there are many radial small blades on both sides of its outer edge. There is an annular flow channel of equal section on the pump casing at the corresponding part of the blade. The entire flow channel is divided into suction and discharge sides by a tongue, which are connected with the suction and discharge pipes of the pump respectively. When the liquid in the pump rotates together with the impeller, a certain centrifugal force is generated, which is thrown outward into the annular flow channel in the pump casing, and forced to return under the restriction of the flow channel shape, and re enter the next blade channel from the blade root. Therefore, the movement trace of the liquid between the blade and the annular flow channel is a forward spiral for the stationary pump shell, and a backward spiral for the rotating impeller. The vortex pump is named for this kind of vortex movement of the liquid. The liquid can be continuousIt enters between the blades for many times to obtain energy until it is finally discharged from the discharge outlet. The vortex pump works somewhat like a multistage centrifugal pump, but the vortex pump does not have an energy conversion device like the volute or guide vane of a centrifugal pump. The vortex pump mainly transmits energy to the liquid through pipes that work continuously for many times, so it can generate higher pressure. In the process of energy transmission, due to the large amount of liquidSecondary impact, large energy loss, low pump efficiency, generally 20-50%. Vortex pump is only suitable for small flow (1-40 m3/h), high lift (up to 250 m)Such as fire pump, gasoline pump on aircraft refueling truck, small boiler feed pump, etc. The vortex pump can transport highly volatile and gaseous liquids, but it should not be used to transport thicker liquids with viscosity greater than 7 Pa · s and unclean liquids containing solid particles. The vortex pump features small flow, high head, self-priming function, and can be used to transport solids with viscosity less than 5 ° EBulk particles and liquid similar to water, such as gasoline, kerosene, alcohol, etc., can be used for small steam boiler water supplement, chemical, pharmaceutical, high-rise water supply and other purposes. The flow passage parts also have stainless steel and other materials that can be used to transport acid and alkali corrosive liquids. The temperature of transmission medium is – 20~+80 degrees. From the structure, it can be divided into: single-stage, two-stage, multi-stage, direct connection, etc.
Application of vortex pump
Vortex pump is only suitable for small flow (1-40 m3/h) and high lift (up to 250 m)Such as fire pump, gasoline pump on aircraft refueling truck, small boiler feed pump, etc. The vortex pump can transport highly volatile and gaseous liquids, but it should not be used to transport thicker liquids with viscosity greater than 7 Pa · s and unclean liquids containing solid particles. The vortex pump features small flow, high head, self-priming function, and can be used to transport solids with viscosity less than 5 ° EBulk particles and water like liquids, such as gasoline, kerosene, alcohol, etc., can be used for small steam boiler water supplement, chemical, pharmaceutical, high-rise water supply, etc. The flow passage components are also made of stainless steel and other materials, which can be used to transport acid and alkali corrosive liquids. The temperature of the transmission medium is – 20~+80 degrees.
Classification of vortex pumps
Vortex pump can be divided into closed type and open type according to the form of impeller. The blade groove of closed impeller is equipped with intermediate diaphragm; the open impeller has no intermediate diaphragm.
From the structure, it can be divided into: single level, double level, multi-level; direct connection form, etc.
Selection guide of vortex pump
The vortex pump needs to pay attention to a self estimated flow, head, pressure, etc. in the selection process. The following provides a formula for the vortex pump, hoping to help everyone!
The calculation formula of pressure and flow for vortex pump selection is as follows:

H=φu/2g；

Q=cF.

In the formula:

U – circumferential speed of impeller;
φ – coefficient, 3.5-4.5;
F – sectional area of channel;
C – liquid flow velocity in the channel, approximately c=u/2 or (0.55-0.65) u.

The blades of the impeller are generally 24-60.
Daily maintenance of vortex pump
1. Frequently check whether there is calcium base grease in the bearing. 2. Frequently check whether the impeller is worn.
3. The motor temperature shall not exceed 70 ℃ during operation.
4. If any fault is found, stop the machine immediately for inspection. When stopping the machine, turn off the pressure gauge, stop the motor, and quickly turn off the pressure gauge on the pressure pipe.
5. When starting the motor, first open the feed valve, open the pressure gauge, adjust the gate valve on the pressure out pipeline, and adjust the pressure gauge reading to the required position.
6. After maintenance, rotate the coupling, verify that the rotor rotates easily, check the motor rotation, and then connect the motor.
7. Shut down for a short time. If the ambient temperature is lower than the freezing point of the liquid, vent the liquid. If the pump is shut down for a long time, it should be properly stored after disassembly, cleaning, oiling and reassembly.
Matters needing attention
1. When the pump outlet valve is closed, the continuous working time of the pump shall not exceed 3 minutes. (The pressure in the pump is too high, which may damage the sealing device)
2. When the pump with mechanical seal smokes due to the lack of cooling water, do not rush to turn on the cooling water. Stop the pump first, and then turn on the pump after natural cooling to normal temperature to avoid cracking of the mechanical seal.
3. It is absolutely prohibited to use the pump inlet valve to regulate the flow to avoid cavitation damage to the pump
4. The opening of the outlet valve should not be too small. The pump works under the condition of less than 30% of the design flow, and the pressure is too large, which is easy to damage the pump.
Troubleshooting of vortex pump
Treatment methods for common faults of vortex pump are as follows:
1. Fault: the vortex pump does not absorb water, and the pressure gauge jumps violently.
Cause: insufficient water is injected, air is accumulated in the pump, and air leaks from the suction pipe and meter pipe.
Solution: Fill enough water and check the pipeline to eliminate air leakage.
2. Fault: The vacuum gauge indicates high vacuum, and the pump still does not absorb water.
Cause: The bottom valve is not opened or seriously blocked. The suction pipe has high resistance. The suction height is too high.
Solution: Check the flexibility of the bottom valve valve, remove the blockage, make the suction pipe as simple as possible, and reduce the suction height.
Troubleshooting for common faults of vortex pump:
3. Fault: the outlet pressure gauge indicates that there is pressure, and there is little or no water from the pump.
Cause: The outlet pipe has large resistance, wrong steering, blocked impeller and insufficient speed.
Solution: reduce the pipe resistance. Check the motor rotation direction. Remove the impeller blockage. Increase the speed.
4. Fault: The vortex pump flow is lower than the design flow.
Cause: Impeller is blocked, seal ring clearance is excessively worn, and speed is insufficient.
Solution: remove the blockage, replace the sealing ring, and increase the rotating speed to the specified value on the nameplate.
5. Fault: The vortex pump consumes too much power.
Cause: The packing is pressed too tightly, the packing chamber is heated, the impeller is worn, and the pump water supply is too large.
Solution: loosen the packing gland. Replace the impeller. Turn down the gate valve to reduce the flow.
6. Fault: The sound inside the vortex pump is abnormal, and the pump does not discharge water.
Cause: The resistance of the suction pipe is too high. The suction height is too high. There is air entering the suction pipe. The temperature of the pumped liquid is too high.
Solution: Check whether the suction pipe is blocked. Clean the bottom valve, lower the liquid temperature or lower the suction height.
7. Fault: pump vibration
Cause: The pump shaft and motor shaft are not concentric. The impeller is unbalanced. The bearing clearance is too large.
Solution: Adjust the pump and motor to align the axis. The impeller passes the balance test, and the unbalanced weight is required to be about 3g. Replace the bearing.

16. Diaphragm pump

What is a diaphragm pump?

Diaphragm pump, also known as control pump, is the main type of actuator. It receives the control signal output by the modulation unit. The diaphragm pump uses power operation to change the fluid flow. There are four materials of the diaphragm pump: plastic, aluminum alloy, cast iron, and stainless steel. The diaphragm pump uses nitrile rubber, neoprene, fluororubber, polyvinylidene fluoride, and polytetraethylene according to different liquid media. To meet the needs. It is installed in various special occasions to pump various media that cannot be pumped by conventional pumps.
Working principle of diaphragm pump
Working principle of pneumatic diaphragm pump:
In the two symmetrical working chambers of the pump, each is equipped with an elastic diaphragm. The connecting rod connects the two diaphragms into one. After the compressed air enters the air distribution valve from the air inlet connector of the pump, it pushes the diaphragms in the two working chambers to move, driving the two diaphragms connected by the connecting rod to move synchronously. At the same time, the gas in the other working chamber is discharged out of the pump from the back of its diaphragm. Once it arrivesAt the end of the process, the air distribution mechanism will automatically introduce compressed air into another working chamber, pushing the diaphragm to move in the opposite direction, thus forming a synchronous reciprocating motion of the two diaphragms. Each working chamber is also equipped with two one-way ball valves. The reciprocating motion of the diaphragm will cause changes in the volume of the working chamber, forcing the two one-way ball valves to open and close alternately, thus making the liquid continuousInhale and discharge continuously.
Application of diaphragm pump
Diaphragm pump is a new type of conveying machinery, which can transport all kinds of corrosive liquids, liquids with particles, high viscosity, volatile, flammable and highly toxic liquids.
Classification of diaphragm pumps
The diaphragm pump can be divided into pneumatic diaphragm pump, electric diaphragm pump and hydraulic diaphragm pump according to the power used by its actuator.
Selection Guide of Diaphragm Pump
The function of diaphragm pump in process control is to receive the control signal of regulator or computer, change the flow of the regulated medium, and maintain the regulated parameters within the required range, so as to achieve the automation of the production process. If the automatic regulation system is compared with the manual regulation process, the detection unit is the human eye, and the regulation control unit is the human brain, then the execution unit -The membrane pump is the hand and foot of human beings. To realize the regulation and control of a certain parameter of the process, such as temperature, pressure, flow, liquid level, etc., the membrane pump is indispensable. Therefore, the correct selection of the membrane pump is of great significance in the automation process.
1. Composition and classification
Diaphragm pump, also known as control pump, is the main type of actuator. By receiving the control signal output by the regulating control unit, the fluid flow can be changed by power operation. Diaphragm pump generally consists of actuator and valve. According to the power used by the actuator, diaphragm pump can be divided into pneumatic, electric and hydraulic types, namely pneumatic diaphragm with compressed air as the power sourceThe pump is an electric diaphragm pump powered by electricity, and a hydraulic diaphragm pump powered by the pressure of liquid medium (such as oil).
2. Selection of type
Selection of valve body type of diaphragm pump The selection of valve body is the most important link in the selection of diaphragm pump. There are many types of diaphragm pump valve bodies.
(1) The shape and structure of the valve core are mainly considered according to the selected flow characteristics, unbalanced force and other factors.
(2) Wear resistance When the fluid medium is an emulsion containing high concentration of abrasive particles.
(3) Corrosion resistance As the medium is corrosive, the valve with simple structure shall be selected as far as possible when it can meet the regulation function.
(4) Medium temperature and pressure When the medium temperature and pressure are high and vary greatly, select the valve whose data of valve core and valve seat are subject to small changes in temperature and pressure.
Selection of diaphragm pump actuator
Consideration of output force
No matter what type of actuator is, its output force is used to overcome the load effectively (mainly refers to the action of unbalanced force and unbalanced moment plus friction, sealing force, gravity and other related forces).
Determination of actuator type
3. Selection of action pipeline
There are four combination forms, namely positive (air close type), positive and negative (air open type), positive and negative (air open type), negative and negative (air close type) a) process production safety; b) medium characteristics; c) product quality assurance with minimum economic loss.
4. Selection of characteristics
The flow characteristic of diaphragm pump refers to the relationship between the relative flow of medium flowing through the valve and the displacement (the relative opening of the valve). The ideal flow characteristics mainly include straight line, equal percentage (logarithm), parabola and quick opening. The characteristic curve and valve core shape are shown in Figure 1 and Figure 2. The commonly used ideal flow characteristics include straight line, equal percentage (logarithm) and quick opening.
Consider from the following aspects: ① analyze and select the regulation quality of the regulation system; ② consider the process piping; ③ analyze the load change.
5. Caliber selection
1) Determination of calculated flow. Qmax and Qmin of calculated flow are determined by the existing production capacity, equipment load and medium conditions
2) Determine the pressure difference before and after the valve. Mark S (resistance coefficient) according to the selected valve flow characteristics and system characteristics, and then determine the calculated pressure difference.
3) Calculate Cv. Select appropriate calculation formula and chart according to the adjusted medium to obtain Cmax and Cmin
4) Select Cv. According to Cmax, extract the first level C>Cmax and closest to it from the selected product standard series
5) Check calculation of diaphragm pump opening. Generally, the opening at the maximum calculated flow is ≯ 90%, and the opening at the minimum calculated flow is ≮ 10%.
6) Checking calculation of actual adjustable ratio of diaphragm pump. Generally, the actual adjustable ratio is ≮ 10.
7) Determination of valve seat diameter and nominal diameter. After verification, determine according to C.
The selection of diaphragm pump is a very meticulous work, which requires not only solid professional theoretical knowledge, but also rich practical experience. A good selection is not only conducive to the setting of PID parameters of the regulating control circuit, so that the adjusted parameters can be better controlled, but also the service life of the diaphragm pump can be greatly increased. The selection of diaphragm pump should be based on local conditions, not unchangeable, but also in practiceIn the process of continuous summary and innovation, especially with the application of mechatronics technology, computer and digital information technology, the structure and function of diaphragm pump has become better and more comprehensive, providing great convenience for the selection of diaphragm pump.
Diaphragm pumpMaintenance

(1) Check whether the diaphragm pump pipeline and joint are loose. Rotate the diaphragm pump by hand to see whether it is flexible.
(2) Add bearing lubricating oil into the bearing body, observe that the oil level should be at the center line of the oil pointer, and the lubricating oil should be replaced or supplemented in time.
(3) Unscrew the water diversion plug of the diaphragm pump body, and inject water (or slurry).
(4) Close the gate valve, outlet pressure gauge and inlet vacuum gauge of the water outlet pipeline.
(5) Inch the motor to see if the rotation direction of the motor is correct.
(6) Start the motor. When the diaphragm pump is in normal operation, open the outlet pressure gauge and the inlet vacuum pump, and gradually open the gate valve, and check the motor load.
(7) Try to control the flow and lift of the diaphragm pump within the range indicated on the label to ensure that the diaphragm pump operates at the highest efficiency point, so as to obtain the maximum energy saving effect.
(8) During the operation of diaphragm pump, the bearing temperature shall not exceed the ambient temperature by 35C, and the maximum temperature shall not exceed 80C.
(9) If abnormal sound is found in the diaphragm pump, stop the pump immediately to check the cause.
(10) When the diaphragm pump is to be stopped, first close the gate valve and pressure gauge, and then stop the motor.
(11) The lubricating oil of diaphragm pump shall be changed after 100 hours in the first month of operation, and then every 500 hours.
(12) Regularly adjust the packing gland to ensure that the leakage in the packing chamber is normal (it is better to leak in drops).
(13) Regularly check the wear condition of the shaft sleeve, and timely replace it if it is worn seriously.
(14) When the diaphragm pump is used in cold winter, it is necessary to unscrew the drain plug at the lower part of the pump body to drain off the medium after shutdown to prevent frost cracking.
(15) If the diaphragm pump is out of service for a long time, it is necessary to disassemble all the pumps, wipe off the water, coat the rotating parts and joints with grease, and install them properly.

Matters needing attention
1. Start and stop load operation
The diaphragm pump is driven by a variable-frequency motor. If the startup and shutdown load is too large or too small, the load fluctuation is large in a short time, and the pump operates under low load for a long time, the inverter will be affected. In order to avoid the above situations, it is hard to control the startup and shutdown load at about 30%, and it is set in the instrument so that the load increase and decrease can be completed within a period of time, effectively from the perspective of technologyThe inverter is maintained.
2. Pressure system operation
The instrument air and lubricating oil pressure of the diaphragm pump are interlocked with the main motor. The oil injection and oil discharge valves of the propulsion fluid are air closed valves, and a certain air pressure must be maintained at all times. The minimum operating pressure of the two valves is not less than 0.4MPa, so the instrument air pressure is generally maintained above 0.15MPa. Even after the pump is stopped, the instrument air is not stopped, so as to avoid insufficient or excessive liquid in the propulsion fluid chamber and supplyThe air of the valve is filtered and oil atomized.
During the operation of the diaphragm pump, the lubricating oil pressure should not be lower than the pressure interlock value (0115MPa), and the differential pressure of the lubricating oil outlet screening procedure should not be too large. The steel ball in the lubricating oil flow camera should be at the upper limit. When adjusting this flow, the adjustment range should not be too large, so as to avoid the interlocking trip caused by too rapid pressure drop due to the instantaneous excessive flow.
Through the above process improvement and the proficiency in the key points of operation, the diaphragm pump has always had a stable process environment during operation. Since its operation for more than a year, it has only tripped once due to electric power, achieving a long cycle, safe and efficient operation.
Troubleshooting
The diaphragm pump shall be free of abnormal sound during operation, and all parts shall be free of running, emitting, dripping and leakage. The pressure gauge and control valve shall work reliably, and all performance indicators shall meet the rated capacity in the instruction manual or production requirements. However, failures may occur due to normal wear or aging of parts data.
1、 Causes and solutions of insufficient or rising pressure of diaphragm pump:
1. Improper adjustment of pressure regulating valve of pneumatic diaphragm pump; adjust the pressure valve to the required pressure
2. The pressure regulating valve is out of order; repair the pressure regulating valve 3 and the pressure gauge; repair or replace the pressure gauge
2、 Cause and treatment of pressure drop fault of diaphragm pump:
1. The oil replenishing valve is insufficient; repair the oil valve
2. Insufficient feeding or leakage of feeding valve; overhaul feeding condition and feeding valve
3. The plunger seal leaks oil; repair the seal part
4. Oil level of oil storage tank is too low; fill new oil
5. The pump body leaks or the diaphragm is damaged; check and replace the sealing gasket or diaphragm.
3、 Cause and treatment of insufficient flow of diaphragm pump:
1. Discharge the first part of the feed and discharge valve; repair or replace the feed valve
2. Diaphragm damaged; replace the diaphragm
3. The speed is too slow and the regulation fails; repair the control device and adjust the speed.
4、 The causes and treatment methods of diaphragm pump oil leakage fault: the sealing gasket and sealing ring are damaged or too loose; adjust or replace the sealing gasket and sealing ring. The pneumatic diaphragm pump acts, but the flow is small or no liquid flows out:

1. Check the cavitation of the pneumatic diaphragm pump, and reduce the pump speed to let the liquid enter the liquid chamber.
2. Check whether the valve ball is stuck. If the operating liquid is incompatible with the elastomer of the pump, the elastomer will expand. Please replace the elastomer of appropriate material.
3. Check whether the joint at the pump inlet is completely locked without leakage, especially the clamp near the inlet valve ball.

The air valve of the pneumatic diaphragm pump is iced: check whether the water content of the compressed air is too high, air bubbles are generated at the outlet of the pneumatic diaphragm pump installed with the air drying equipment pump: check whether the diaphragm is broken, and check whether the clamp is locked, especially the inlet pipe clamp.
The product flows out from the air outlet: check whether the diaphragm is broken, check whether the diaphragm and the inner and outer clamping plates are on the shaft and whether the clamping valve rattles: increase the outlet or inlet head.
Disassembly and reassembly guide of pneumatic diaphragm pump:
Warning: Before repairing the pump, it is necessary to remove the air source piping from the pump and discharge the air pressure in the pump. Remove all pipelines connecting the inlet and outlet of the pump, and then discharge the fluid in the pump into an appropriate container. Wear protective caps, glasses, gloves。
5、 The pump does not act or operates slowly:

1. Check whether the filter screen or air filter device at the air inlet end has impurities.
2. Check whether the air valve is stuck, and clean the air valve with cleaning solution.
3. Check whether the air valve is worn, and replace it with new parts if necessary.
4. Check the sealing parts of the center body. If they are severely worn, the sealing effect will not be achieved, and the air will be discharged from the air outlet end. Because of its special structure, please only use GLYD ring.
5. Check whether the piston in the air valve moves normally.
6. Check the type of lubricating oil. If the added lubricating oil is higher than the viscosity of the recommended oil, the piston may be stuck or operate abnormally. It is recommended to use light and antifreeze lubricating oil.

17. Submersible pump

What is a submersible pump?

Submersible pump is an important equipment for deep well water lifting. When in use, the whole unit works in the water to extract groundwater to the surface. It is used for domestic water, mine rescue, industrial cooling, farmland irrigation, seawater lifting, ship load adjustment, and can also be used for fountain landscape.
Hot water submersible pump is used in hot spring sauna, can also be used to extract groundwater from deep wells, can also be used in rivers, reservoirs, canals and other water lifting projects. It is mainly used for farmland irrigation and human and livestock water in alpine areas, and can also be used for central air conditioning cooling, heat pump units, cold pump units, urban, factory, railway, mine and site drainage. The general flow can reach (5m3~650m3)The head can reach 10-550 meters per hour.
Working principle of submersible pump
There are several kinds of submersible pumps. The wire bundles in the motor are oil immersed, water immersed and dry type. You must read the manual before use. You can’t make mistakes. If you don’t use it for a long time, you must rotate the impeller before use, otherwise you will burn the package because it is not stuck for a long time. Before starting the pump, the suction pipe and the pump must be full of liquid. After starting the pump, the impeller rotates at a high speed, and the liquid in the impeller rotates with the bladeIt rotates. Under the centrifugal force, it flies away from the impeller and shoots out. The speed of the ejected liquid in the diffusion chamber of the pump housing gradually slows down, and the pressure gradually increases. Then it flows out from the pump outlet and the discharge pipe. At this time, a vacuum low-pressure area without air or liquid is formed at the center of the blade because the liquid is thrown around. The liquid in the liquid pool is under the effect of atmospheric pressure on the pool surface,It flows into the pump through the suction pipe, and the liquid is continuously pumped up from the liquid pool and continuously flows out from the discharge pipe.
Application of Submersible Pump
Submersible pump is an important equipment for deep well water lifting. When in use, the whole unit works in the water to extract groundwater to the surface. It is used for domestic water, mine rescue, industrial cooling, farmland irrigation, seawater lifting, ship load adjustment, and can also be used for fountain landscape.
The hot water submersible pump is used in hot spring sauna, can also be used to extract groundwater from deep wells, can also be used in rivers, reservoirs, canals and other water lifting projects. It is mainly used for farmland irrigation and human and livestock water in alpine areas, and can also be used for central air conditioning cooling, heat pump units, cold pump units, urban, factory, railway, mine, and site drainage.
Classification of submersible pumps
The development and use demand of pumps are combined with the progress of science and technology, and there are many kinds of pumps. Submersible pumps can be divided into well submersible pumps, working face submersible pumps, submersible sewage pumps, sediment discharge submersible pumps, mining vertical pumps, etc.
As far as the medium used is concerned, submersible pumps can generally be divided into clean water submersible pumps, sewage submersible pumps and seawater submersible pumps (corrosive).
Selection Guide of Submersible Pump
List basic data:
1. Characteristics of media: media name, specific gravity, viscosity, corrosivity, toxicity, etc.
2. The diameter and content (mass or volume percentage) of solid particles contained in the medium.
3. Medium temperature: (℃).
4. Required flow
In the process flow of general industrial pumps, the leakage in the pipeline system can be ignored, but the impact of process changes on the flow must be considered. If the agricultural pumps use open channels for water delivery, leakage and evaporation must also be considered.
5. Pressure: pressure drop (head loss) in the pressure pipeline system of the suction pool pressure drainage pool.
6. Pipe system data (pipe diameter, length, type and number of pipe accessories, geometric elevation from the suction tank to the pressure tank) shall be provided with device characteristic curve if necessary. The following matters shall be noted when designing and arranging pipes:

A. Reasonable selection of pipe diameter Large pipe diameter under the same flow rate, small liquid flow velocity, small resistance loss, but high price Small pipe diameter will lead to a sharp increase in resistance loss, which will increase the head of the selected pump, increase the matching power, increase the cost and operation cost, so it should be comprehensively considered from the perspective of science, technology and economy.
B. The maximum pressure that the discharge pipe and its pipe joint can bear shall be considered.
C. The pipeline shall be arranged as straight as possible to minimize the number of accessories in the pipeline and the length of the pipeline. When the pipeline has to turn, the bending radius of the elbow shall be 3~5 times the diameter of the pipeline. The angle shall be greater than 90 ℃ as far as possible.
D. The discharge side of the pump must be equipped with valves (ball valves or stop valves, etc.) and check valve valves to regulate the working point of the pump. The check valve can prevent the pump from reversing when the liquid flows back and prevent the pump from being hit by water hammer (when the liquid flows back, it will produce huge reverse pressure and damage the pump).

2. Determine flow head
Determination of flow
a. If the minimum, normal and maximum flow rates have been given in the production process, the maximum flow rate shall be considered.
b. If only normal flow is given in the production process, a certain margin should be considered. For large flow with ns>100 and low flow rate, the unexpected head pump flow margin should be 5%. For small flow high head pump with ns>50, the flow margin should be 10%. For pump with ns ≤ 100, the flow margin should be 5%. For pump with poor quality and poor operating conditions, the flow margin should be 10%.
c. If the basic data only give weight flow, it should be converted into volume flow.
Maintenance of submersible pump
Daily maintenance of submersible pump. Check whether the power line is damaged every day, and it is absolutely prohibited to launch the submersible pump with electric leakage. Check whether the pump body is damaged every day to ensure that the motor does not leak electricity during operation. After the work is completed, the sundries attached to the pump should be cleaned in time, and the pump should be washed clean. To ensure the normal operation of the submersible pump, the following requirements must be followedBefore use, check the insulation resistance of the motor with a megger, and the minimum value shall not be less than 50M Ω.
The water filled motor should open the water filling plug, fill it with clean water, and then tighten the plug. It is not allowed to screw off the water filling plug and directly enter the well. Before use, check whether the cable is broken or broken. If it is damaged, replace it in time to prevent leakage. Before launching, the submersible pump should inject clean water into the pump, and then idle for 1-2 minutes, and start it twice. Check whether the start and idle are normalWhether the direction meets the requirements. If the direction of rotation is opposite, replace the wiring of any two phases. Check whether the lifting pipe has cracks and whether the connection is firm. When the submersible pump is lowered into the well and lifted, it is not allowed to pull the cable hard to avoid damage to the cable or disconnection of the connector, which may cause unexpected accidents. It should be lowered into the well and lifted with iron wires or pallets.
The power supply voltage should be controlled within ± 5% of the rated voltage, so that the motor can work normally. If the voltage is too low or too high, the motor cannot continue to be used, so as to avoid the damage of the motor when working under overvoltage or undervoltage for a long time. When diving into the water, the submersible pump should be lifted vertically, not inclined. The water depth should be 5 meters below the dynamic water level. The submersible pump should not transport sand with a relatively high contentHigh water or mud. The actual head of the submersible pump should be 0.8-1.1 times the rated head to improve the unit efficiency, save energy, and avoid motor overload.
The wiring of the submersible pump motor must be firmly connected to prevent the motor from burning due to the lack of phase operation. The cable must be frequently checked for cracks, scratches and other conditions, and should be replaced or repaired in a timely manner. If oil leakage occurs to the oil immersed motor, it should be timely repaired at the manufacturer or maintenance point, and the sealing elements should be replaced. The sand particles in the motor cavity should be regularly cleaned and the clean water in the motor cavity should be replaced for the water immersed motorAfter the pump runs for half a year, it shall be repaired and inspected, and damaged parts shall be replaced. After the submersible pump is used, the water immersed motor shall be drained of clean water, the pump shall be cleaned, oiled for rust prevention, and stored vertically in a dry place.
Matters needing attention
1. Installation of leakage protector
Leakage protector is also called life protector, and its function can be understood from the word “life protector”. Because the submersible pump works underwater, it is easy to cause electric energy loss and even electric shock. If leakage protector is installed, as long as the leakage value of the submersible pump exceeds the action current value of the leakage protector (generally not more than 30 mA)The leakage protector will cut off the power supply of the submersible pump to avoid leakage and waste of electric energy and ensure safety.
2. Do not start the machine if the power supply voltage is abnormal
Due to the long low-voltage power supply line in rural areas, it is common that the voltage at the end of the line is too low. When the phase voltage is lower than 198 V and the line voltage is lower than 342 V, the speed of the submersible pump motor drops. When the speed does not reach 70% of the rated speed, the starting centrifugal switch will be closed, causing the starting winding to be electrified for a long time, heating and even burning the winding and capacitor. On the contrary, too high voltage will cause the motor to overheatThe winding is burnt out due to heat. Therefore, the operator must observe the power supply voltage value at any time when the submersible pump is working. If the voltage is less than 10% of the rated voltage and more than 10% of the rated voltage, the motor should be stopped to find out the cause and eliminate the fault.
3. Avoid frequent switching
Do not switch on and off the submersible pump frequently. This is because the electric pump will produce backflow when it is stopped. If it is started immediately, the motor will start with load, resulting in excessive starting current and burning out of the winding. Since the current is large when starting, frequent starting will also burn out the motor winding of the submersible pump.
4. Do not allow the submersible pump to work overload for a long time
In order to avoid long-term overload operation of submersible electric pump, do not pump water with large sand content and observe whether the current value is within the specified value on the nameplate at any time. If the current is found to be too large, stop the pump for inspection. In addition, the dewatering operation time of the electric pump should not be too long to avoid overheating and burning of the motor.
5. The rotation direction of the motor shall be correct
The rotation direction of the motor should be clear. There are many types of submersible pumps that can discharge water in both forward and reverse rotation, but the water output is small and the current is large when reversing, and the motor winding will be damaged if the reversing time is long.
6. Insulation resistance requirements for cable installation and submersible pump
When installing the submersible pump, the cable should be overhead and the power line should not be too long. When launching or lifting the submersible pump, do not force the cable to avoid breaking the power line. When the submersible pump is working, do not sink into the mud, or it will lead to poor heat dissipation of the motor and burn the motor winding. When installing, the insulation resistance of the motor should not be less than 0.5 megohm.
7. Check on duty, find problems and repair them in time
The motor shall be checked frequently at ordinary times. If cracks are found on the lower cover, rubber sealing ring is damaged or invalid, it shall be replaced or repaired in time to avoid water infiltration into the submersible pump.
Troubleshooting of submersible pump
Submersible pumps often encounter problems such as low impeller speed, small flow, no rotation of the impeller, oil leakage, electric leakage and so on in use, resulting in reduced work efficiency.

1. The speed of the impeller is low, and the head cannot be reached: when we just bought the submersible pump, we often try it, but during the trial, we will find that the actual head does not reach the standard head, and the speed of the impeller is also very low. In this case, please do not panic. It may be that the wiring is incorrect, and it is recommended to replace the fuse. It may also be that the submersible pump is inferiorCheng can’t reach it, so I suggest buying products of high quality.
2. The submersible pump has weak water output and small flow: take out the submersible pump, check that the rotor rotates flexibly and the rotor can rotate when powered on. After disassembling the pump, it is found that the lower shaft of the submersible pump is loose from the bearing, and the rotor moves down, so the rotor rotates weakly and the output power is small. Use appropriate gaskets to pad between the rotor and the bearing, so that the rotor moves up, and then install and test the machine, and the fault can be eliminated.
3. After powering on, the impeller does not rotate: if the submersible pump has a buzzing AC sound after powering on, the impeller does not rotate. Please cut off the power supply and pull the impeller at the water inlet. If the impeller cannot be pulled, it means that the rotor is stuck. If the impeller can be pulled, but the impeller does not rotate after powering on, the fault reason may be that the bearing is severely worn, and the magnetism generated by the stator during powering on absorbs the rotor and cannot rotate.Replace the bearing and then assemble the water pump. Move the impeller flexibly and troubleshoot.
4. Oil leakage: oil leakage of submersible pump is mainly caused by severe wear of seal box, which causes oil leakage of seal box oil chamber or poor sealing at outlet box.
5. Electric leakage: electric leakage is the most common fault of submersible pump and one of the most dangerous factors endangering personal safety. Therefore, special attention should be paid. The fault phenomenon is that when the switch blade is closed, the leakage protector in the transformer distribution room will trip (if there is no leakage protector, it will be quite dangerous, and the motor will be burned out).

18. Impurity pump

What is a trash pump?

Impurity pump is mainly composed of pump body, impeller, pump cover, shaft, front guard board, rear guard board, shaft sleeve, fixed cutter head, moving cutter, suspension, bearing parts, etc. The pump body is designed to open the front and rear doors, which has the advantage that during maintenance, the pump body, pipeline, rotor parts, maintenance or replacement, and fixed cutter head are not removed.
The suspension bearing components support the rotor components of the pump. In order to balance the axial force of the pump, a pair of blades is set at the rear cover of the impeller. The rolling bearing bears the radial force and residual axial force of the pump. The impurity pump adopts a mechanical seal. At the part where the shaft passes through the mechanical seal, a shaft sleeve is installed to protect the pump shaft from wear. An “O” type seal ring is installed between the shaft sleeve and the shaft to prevent air intake and water leakage.
The pump body covers the flow passage parts. This series of impurity pumps are single-stage, single suction centrifugal impurity pumps. Among them, the PNL type is a vertical structure. The flow passage parts are made of wear-resistant alloy materials, and the PNJ type is made of rubber materials, with a long service life. The clearance between the impeller and the sheath and between the impeller and the guard plate can be adjusted to maintain high efficiency.
With the development of economy and technology, there are still many special materials to be treated in many fields, such as garbage, sewage, gravel, bones, animal fur, solid materials, etc. At this time, special tools are needed to deal with them, and the impurity pump plays the role of scavenger.
Operating principle of impurity pump
When the trash pump is working, it mainly supports the rotor part of the pump through the suspension bearing parts. To balance the axial force of the pump, a pair of blades is set at the rear cover of the impeller. The rolling bearing bears the radial force and residual axial force of the pump.
Application of Impurity Pump
Centrifugal impurity pump is used to transport liquid media, such as mud, ash, sand, sugar juice, feed, coal water, colloidal particles, feces and other solid or suspended solids. It is widely used in chemical industry, mining, metallurgy, urban sewage treatment and other industries. According to different transmission media, centrifugal impurity pump can be divided into mud pump, ash pump, sand pump, coal pump, colloidal particles pump, sugar juice pump, etc.
Classification of trash pump
Impurity pumps can be divided into vane pumps (centrifugal pumps, mixed flow pumps and axial flow pumps), reciprocating pumps and other types of pumps (including screw pumps, jet pumps, hose pumps, hydraulic lift pumps and concrete pumps). Centrifugal impurity pumps are the most widely used, accounting for the largest proportion of impurity pumps. According to their uses, they can be divided into slurry pumps, mud pumps, sand pumps, gravel pumps, dredge pumps, foam pumps, etc.
Selection Guide for Impurity Pump
Centrifugal impurity pump is used to transport liquid media, such as mud, ash, sand, sugar juice, feed, coal water, colloidal particles, feces and other solid or suspended solids. It is widely used in chemical industry, mining, metallurgy, urban sewage treatment and other industries. According to different transmission media, centrifugal impurity pump can be divided into mud pump, ash pump, sand pump, coal pump, colloidal particles pump, sugar juice pump, etc.
Material selection: The trash pump requires that the flow passage parts have corresponding wear resistance, and wear resistant materials are often selected to adjust the use needs of various trash pumps. For example, gray cast iron, high silicon cast iron, nickel chromium cast iron, cast steel, chromium cast steel, manganese chromium molybdenum cast steel, titanium and titanium alloys, natural rubber and synthetic rubber, or made into flow passage parts, or made into jackets, lining plates embedded in the flow passage partsIf the pump is blocked, the impeller shall be open. If the closed impeller is used, the impeller width shall be increased or the number of blades shall be reduced.
Maintenance of impurity pump
(1) Check whether the joints of the pump and pipeline are loose. Rotate the pump by hand to see whether the pump is flexible, and then check the motor rotation.
(2) Connect flushing cooling water to the pipe joint of mechanical seal chamber.
(3) Fill the pump with water
(4) Close the gate and outlet pressure gauge of the outlet pipe.
(5) Start the motor. When the pump runs normally, open the outlet pressure gauge and gradually open the gate valve until it displays the appropriate pressure. At the same time, check the motor load.
(6) Try to control the flow and head of the pump within the range indicated on the pump label to ensure that the pump operates near the high efficiency point for a long time, so as to obtain the maximum energy saving effect.
(7) During the operation of the pump, the bearing temperature rise shall not exceed the ambient temperature by 35 ℃, and the maximum temperature shall not exceed 80 ℃.
(8) If any abnormal sound is found during the operation of the pump, stop the pump immediately to check the cause.
(9) When the pump is to be stopped, first close the gate valve and pressure gauge, and then stop the motor.
(10) Pay attention to the lubrication of the bearing, and inject grease into the bearing chamber regularly.
(11) When the pump is used in cold winter, the drain plug at the lower part of the pump body must be unscrewed after shutdown to drain the water completely to prevent frost cracking.
(12) If the pump is used for a long time, all the pumps must be disassembled and wiped dry, and the rotating parts and joints must be coated with grease and installed properly.
Matters needing attention

1. Before using the pump, carefully check whether the cable is damaged, whether the fasteners are loose or fall off, and whether the pump is deformed or damaged during transportation, storage and installation.
2. Use a 500V megohmmeter to measure the same and phase to ground insulation resistance of the electric pump motor, and the value should not be less than 2 megohm, otherwise the motor stator winding should be dried, and the drying temperature should not exceed 120 ℃.
3. This series of sewage pumps can be installed in both fixed and mobile types. When fixed automatic installation is adopted, the chain cable should be threaded separately (deviated from the pump outlet, and its connection should be parallel to the pump outlet)Lift the electric pump up and down in the two eyebolts or lifting plates. Slide down along the guide rail evenly and slowly until the automatic coupling is in place. When using mobile installation, cover the hose first, and use the chain cable to penetrate the two eyebolts to lift the electric pump up and down. Be careful not to use the cable as a rope to avoid danger.
4. After the pump is connected, the rotation direction is counterclockwise from the water inlet. If the electric pump reverses, just switch any two wires in the cable to the wiring position.
5. The casing ground wire of the electric pump must be connected in strict accordance with the relevant regulations. In order to ensure personal safety during use, it is strictly prohibited to install or move the electric pump nearby when it is running, in case of accidents caused by electric leakage of the electric pump.
6. The electric pump must be equipped with a fully automatic water pump control cabinet without special circumstances. Do not directly connect the power grid or use the knife switch to connect the power to ensure the normal operation of the electric pump.
7. It is not allowed to operate the electric pump at low head for a long time (generally, the operating head shall not be less than 60% of the rated head). It is better to control it within the recommended operating head to prevent the electric pump from burning the motor due to overload.
8. The pump without self circulating cooling device shall not be exposed to the water for long-term operation to prevent overheating and damage of the electric pump.

19. Oil pump

What is an oil pump?

The oil pump is a kind of portable and compact pump, which can be divided into three categories: in-line type, distributed type and single type. The oil pump can only operate with power source, and its lower camshaft is driven by the engine crankshaft gear.
The oil pump provides an oil pump with a housing made of aluminum containing data and a movable molded part set in the housing, wherein the movable molded part is at least partially made of a sintered iron base alloy containing at least one austenite, and the molded part made of a sintered data has at least one heat for the housingThermal expansion coefficient of 60%.
Operating principle of oil pump
Oil suction and pressure
The suction and pressure of the fuel injection pump are completed by the reciprocating motion of the plunger in the plunger sleeve. When the plunger is in the lower position, the two oil holes on the plunger sleeve are opened, the internal cavity of the plunger sleeve is connected with the oil channel in the pump body, and the fuel is quickly filled into the oil chamber. When the cam is pushed onto the roller of the roller body, the plunger rises. From the beginning of the plunger movement upward until the oil hole is blocked by the upper end face of the plungerIn this period of time, due to the movement of the plunger, the fuel is squeezed out of the oil chamber and flows to the oil passage. Therefore, this lift is called the pre stroke. When the plunger blocks the oil hole, the oil pressure process begins. The plunger moves upward, and the oil pressure in the oil chamber rises sharply. When the pressure exceeds the spring force of the oil outlet valve and the upper oil pressure, the oil valve is pushed out, and the fuel is pressed into the oil pipe and sent to the fuel injectionDevice.
The time when the oil inlet hole on the plunger sleeve is completely blocked by the upper end face of the plunger is called the theoretical oil supply starting point. When the plunger continues to move upward, the oil supply also continues, and the oil pressure process continues until the helical bevel on the plunger allows the oil return hole of the plunger sleeve. When the oil hole is opened, the high pressure oil flows from the oil chamber to the oil passage in the pump body through the longitudinal groove on the plunger and the oil return hole on the plunger sleeve.At this time, the oil pressure in the oil chamber of the plunger sleeve decreases rapidly, the oil outlet valve falls back to the valve seat under the action of the oil pressure in the spring and high-pressure oil pipe, and the injector stops fuel injection immediately. At this time, although the plunger continues to rise, the oil supply has stopped. The moment when the oil return hole on the plunger sleeve is opened by the oblique edge of the plunger is called the theoretical oil supply end point. During the whole process of upward movement of the plunger, only the middle part of the strokeIt is the oil pressure process, and this stroke is called the effective stroke of the plunger.
Application of oil pump
The fuel injection pump is now mainly used on the diesel engine of the automobile. Usually, the fuel injection pump, governor and other components are installed together to form a whole. The submersible pump is a multi-stage centrifugal magnetic pump, which can be applied to different types of oil wells, and is structurally divided into radial flow and mixed flow.
Classification of oil pumps
The oil pump is divided into fuel injection pump, self-priming pump, submersible pump and engine oil pump.
Selection guide of oil pump
The selection of oil pump shall be based on the process flow and system requirements from five aspects: liquid property, liquid delivery capacity, device pressure, pipeline layout and operating conditions.
1. Liquid properties, including liquid medium name, physical properties, chemical properties and other properties, physical properties include temperature c, density d, viscosity u, solid particle diameter and gas content in the medium, etc. This involves system pressure, required power calculation and appropriate pump type: chemical properties, mainly refers to the chemical corrosiveness and toxicity of liquid medium, and is the selection of pump data and selectionImportant basis for which type of shaft seal to use.
2. Flow is one of the important performance data for selecting and distributing oil pump, which directly affects the production capacity and delivery capacity of the whole unit. When selecting cycloidal gear pump, the maximum flow is taken as the basis, taking into account the normal flow. When there is no maximum flow, 1.1 times of the normal flow is usually taken as the maximum flow. Leakage in the pipeline system can be ignored in the process flow of general industrial pumpsHowever, the influence of process change on flow must be considered.
3. The pressure required by the device system is another important performance data for selecting the gear pump. Generally, the model of the cycloidal gear pump should be selected by increasing the pressure after 5% – 10% allowance. This includes: the pressure of the oil suction pool, the pressure of the oil discharge pool, and the pressure drop (pressure loss) in the pipeline system.
4. The pipeline layout conditions of the oil pump system refer to the liquid delivery height, distance and direction for system pressure calculation and dynamic verification. If necessary, the pipeline system data shall also be provided with the device characteristic curve. When designing the pipeline layout, the following matters shall be noted:

A. Reasonable selection of pipe diameter, large pipe diameter, small liquid flow speed and small resistance loss under the same flow rate, but high price and small pipe diameter will lead to a sharp increase in resistance loss, which will increase the pressure of the selected pump, the matching power, and the cost and operating expenses. Therefore, comprehensive consideration should be given from the perspective of science, technology and economy.
B. The discharge side of the pump must be equipped with a valve and a check valve. The valve is used to adjust the operating point of the pump. The check valve can prevent the reverse rotation of the oil pump when the liquid flows back.
C. The pipeline shall be arranged as straight as possible, the accessories in the pipeline shall be minimized and the pipeline length shall be minimized. When turning is necessary, the bending radius of the elbow shall be 3~5 times the diameter of the pipeline, and the angle shall be greater than 90 ℃ as far as possible.
D. The maximum pressure that the discharge pipe and its pipe joint can bear shall be considered.

5. There are many operating conditions for the oil pump, such as the operating temperature of the liquid, the pressure on the suction side, the pressure on the discharge side, the altitude, the ambient temperature, whether the operation is intermittent or continuous, and whether the position of the gear pump is fixed or movable.
Maintenance of oil pump

During use, it is strictly prohibited to add diesel oil to the gear oil for dilution, and do not bake the rear axle and transmission due to the impact on winter starting, so as to avoid serious deterioration of the gear oil. If this happens, it should be replaced with low viscosity multistage gear oil.
Do not confuse the classification grades of engine oil and oil pump. In the calculation standard, to avoid confusion, it is specified that the higher classification grades are used for gear oil and the lower classification grades are used for engine lubricating oil. However, the classification grades of old grades of gear oil are lower. It should be noted that the viscosity grades of gear oil and engine oil are not related and cannot be used interchangeably with the same model. Gear oil must not be used as engine oil,Otherwise, serious accidents such as bush burning, cylinder sticking and piston crown sintering will occur.
Rational use of the oil pump is conducive to gear maintenance. Gear oil has a long service life. If single grade oil is used, different viscosity grades should be used during seasonal maintenance. If the old oil discharged does not reach the oil change period, it can be used when the oil is changed again. The old oil should be kept properly to prevent water, mechanical impurities and waste oil pollution.
Change the oil in a timely manner. Replace the oil with new oil according to the specified oil change quota. If there is no oil quality analysis method, the oil can be changed within the specified period. The automobile manufacturer recommends an oil change period of 30000-48000km. When changing the oil, the old oil should be discharged while hot, and the gear and gearbox should be cleaned before adding new oil. When refueling, water and impurities should be prevented from mixing.
The amount of oil added should be appropriate. The amount of oil should be appropriate, neither too much nor too little. Too much not only increases the oil stirring resistance and fuel consumption, but also may cause gear oil to mix into the brake drum through the rear axle housing (if the seal is poor)Brake failure will be caused; too little will lead to poor lubrication, too high temperature and accelerated gear wear, which will adversely affect gear maintenance. Generally, the gear oil level should be flush with the lower edge of the gearbox oil filler, and each gear oil tank should be regularly checked for leakage, and each oil seal and gasket should be kept intact.

Matters needing attention
Pay attention to the following aspects for the maintenance of oil pump:

1. Water will corrode the oil pump, so it is prohibited to use the oil pump for vacuum pumping of water containing substances.
2. For substances containing a large amount of solvent, first remove most of the solvent in the oven, and then use the oil pump to vacuum.
3. Use the vacuum pump in the correct order to prevent backdraft.
4. After using the vacuum oven, be sure to do a good job of cleaning, and clean the glass window of the vacuum oven.
5. Wipe off the rust preventive oil on the surface.
6. Remove the antirust oil from the inner cavity of the governor and the injection pump, and add the lubricating oil of the specified brand.
7. The rust proof oil in the fuel pipeline shall also be removed before use. Connect the fuel to the fuel injection pump pipeline, and constantly rotate the camshaft of the fuel injection pump until the tight seat of the fuel outlet valve sprays clean fuel.
8. Fuel selection is reasonable.
9. The fuel with proper grade must be used. Generally, No. 0 diesel oil is used in summer, and No. 10 light diesel oil is used in winter.
10. The fuel used must be clean and free from any impurities and moisture.

20. Sewage pump

What is a sewage pump?

The sewage pump is a kind of pump product which is connected with the motor and works under the liquid at the same time. Compared with the general horizontal pump or vertical sewage pump, the sewage pump is compact in structure and occupies a small area. It is easy to install and maintain. Large sewage pumps are generally equipped with automatic coupling device for automatic installation, which is very convenient for installation and maintenance. The continuous operation time of the sewage pump is longThe machine is coaxial, the shaft is short, and the weight of rotating parts is light, so the load (radial) on the bearing is relatively small, and the service life is much longer than that of ordinary pumps. There is no cavitation damage and water filling problems. Especially the latter point brings great convenience to operators. The vibration noise is small, the motor temperature rise is low, and there is no pollution to the environment.
Working principle of sewage pump
Mechanical principleIt can automatically control the start and stop of the pump according to the change of the required liquid, without the need of special personnel, which is extremely convenient to use. It can be equipped with a double guide rail automatic coupling installation system according to the user’s needs, which brings great convenience to the installation and maintenance, and people do not have to enter the sump for this purpose. It can be used within the full head range, while ensuring that the motor will not be overloaded. There are two different installation methods for the sewage pumpType, fixed automatic coupling installation system, and mobile free installation system. The structure and performance of the self-priming sewage pump in the sewage pump, drawing on the advantages of similar products at home and abroad, and absorbing the use requirements and improvement suggestions of users in many aspects, has been developed to integrate self-priming and sewage, which can be like ordinary clean water self-priming pumps without bottom valve installation and irrigationWater can also suck dirt, sediment, waste mineral impurities, fecal treatment, and all engineering sewage and colloid liquid containing large solid blocks and long fibers.
The automatic installation system automatically connects or disconnects the pump from the pipeline system during installation and disassembly through the coupling device. WQ submersible sewage pump is an indispensable and important equipment in water treatment. Its safe operation directly affects the safe operation of the whole water treatment system. Therefore, in WQ submersible sewage pump, the main problem is to ensure the reliability of the pump, which affects the sewage dischargeThe key problem of pump reliability is the sealing performance and overload free performance of the pump as well as the service life of important parts. In the sealing of the pump, a new sealing technology combining the auxiliary impeller hydrodynamic seal and mechanical seal is adopted, which greatly improves the sealing reliability.
Application of sewage pump
It is suitable for lifting sewage and wastewater containing fibrous dirt, sludge and solid particles of certain size.
1) Submersible sewage pump of foreign import and wholly foreign-owned brand can be used to pump and discharge sewage and waste water with solid particles (φ 20 – φ 80mm) and various long fiber impurities. The temperature of the pumped sewage and waste water does not exceed 60 ℃ (some foreign well-known brand products can reach 90 ℃), and the pH value is 5-9 (some foreign well-known brand products are 6-13), applicable to single building and community construction projects.
2) AS and AV adopt vortex impellers, which are suitable for pumping sewage containing solid particles; QW (WQ) and JYWQ series adopt channel impellers, which are suitable for pumping sewage and wastewater such as fibrous sewage and sludge; AS, AV, QW (WQ)Series and foreign brand ordinary submersible sewage pumps are suitable for sewage and waste water pumping with short retention time and less sediment; JYWQ series automatic mixing submersible sewage pumps can be used for mixing impurities at the bottom of the pump pit to a certain extent.
Classification of sewage pump
Sewage pump can be divided into self-priming sewage pump, submerged sewage pump, knife type sewage pump and automatic mixing sewage pump according to different sewage pipelines.
Sewage pumpSelection Guide

1) The submersible sewage pump brand must be manufactured in strict accordance with the international ISO 9906 or the current domestic standards, and certified as qualified by the comprehensive performance test of the authority.
2) According to the user’s needs, the quantity and quality of discharged sewage (waste water) and the set position of sewage pool (sump) shall be improved, the flow and head required by the submersible sewage pump shall be reasonably determined, and the pump specifications shall be determined.
3) According to the characteristics of sewage and waste water, determine the type of pump to be used, whether to use cutting and grinding, whether to use vortex impeller or channel impeller, whether to use single channel or double channel (under the same conditions, the anti blocking performance of single channel is better than that of double channels).
4) When selecting the submersible sewage pump, the average time between failures, mechanical seal life, bearing rated life, motor design life, motor insulation grade, and the number of starts and stops per hour of the motor should be known.
5) Submersible sewage pump shall be equipped with leakage protection device, overheat or overload protection device, sealing leakage monitoring device and reliable grounding device.
6) The outdoor sewage pool of the building can be installed with an airtight well cover without a vent pipe. The indoor sewage pool (collecting well) should be installed with an airtight well cover and a vent pipe. The airtight well cover is made of cast aluminum, gray cast iron and nodular cast iron.
7) If the submersible sewage pump is used to pump corrosive wastewater, the pump body shall be made of stainless steel and other corrosion-resistant materials.
8) The submersible sewage pump in the basement should be equipped with dual power supply.
9) When there are multiple brands of products to choose from, it is appropriate to focus on the material, processing accuracy, equipment appearance, necessary functions of flow passage components (large channel, anti winding, anti blocking, etc.) and additional functions (long fiber cutting and tearing, automatic mixing to prevent dirt settling and hardening, etc.) of the main components of the submersible sewage pumpThe supplier promises to make comprehensive comparison in terms of trouble free service life, after-sales service, quotation, etc., and choose the best.
10) The complete set of submersible sewage pump (control cabinet, liquid level element switch, automatic coupling device, etc.) shall be supplied by the supplier in a unified manner; the wearing parts should be accompanied with spare parts; optional parts（Pipeline valve、Pipe fittingsIt can be purchased together with the plumbing equipment of the main installation project, or it can be purchased by the pump supplier.

Maintenance of sewage pump
Sewage pump has been paid more and more attention by people. It can transport all kinds of domestic sewage, industrial waste water, construction site drainage, liquid feed, etc. from the original pure water. It plays a very important role in municipal engineering, industry, hospitals, buildings, hotels, water conservancy construction and other industries. But the key problem for sewage pump is reliabilityThe reason is that the sewage pump is used underwater; the medium conveyed is some mixed liquid containing solid materials; the pump is close to the motor; the pump is arranged vertically, and the weight of rotating parts is in the same direction as the water pressure borne by the impeller. In order to improve the service life of the sewage pump, most manufacturers at home and abroad are trying to find ways to protect the pump, that is, in case of pump leakage, overloadIn case of temperature failure, it can automatically alarm, and automatically shut down for repair. It is necessary to set a protection system in the sewage pump, which can effectively protect the safe operation of the electric pump. But this is not the key to the problem. The protection system is just a remedy after the failure of the pump, which is a more passive method. The key to the problem should be to start from the root and solve it thoroughlyThis is a more active approach to the problems of the pump in terms of sealing and overload. Therefore, the auxiliary impeller hydrodynamic seal technology and the pump overload free design technology are applied to the submersible sewage pump, greatly improving the pump sealing reliability and bearing capacity, and extending the service life of the pump.
When the sewage pump sump cannot be equipped with an accident drainage pipe, the pump should have an uninterrupted power supply; when the drainage inlet pipe can be closed, the pump can not be equipped with an uninterrupted power supply, but an alarm device should be set. When lifting sewage and waste water with large impurities, the outlet pipes of submersible sewage pumps in different sumps should not be discharged together.
Matters needing attention
Precautions for use of sewage pump

(1) Before operation, check the insulation resistance of the motor stator winding to the ground with a megger, and the minimum resistance shall not be less than 50 megohm.
(2) Check whether the cable is damaged or broken. If it is damaged, it must be replaced in time to avoid leakage. The cable section should match the current.
(3) When the voltage exceeds ± 10% of the rated voltage, the electric pump shall not be started.
(4) To ensure safe use, the grounding wire in the four core cable must be reliably grounded to prevent electric shock accidents.
(5) When the electric pump submerges into the water, it should be lifted vertically, and it is not allowed to lay horizontally on the ground, let alone sink into the sludge. When the pump is out of use, it should be lifted and cleaned, placed in a dry place, and pay attention to antifreeze. (6) It is prohibited to use the cable as a lifting rope for installation.
(7) Check the running direction of the rotor, which should rotate clockwise from top to bottom. (8) Outdoor switches or terminals should have rain proof and moisture-proof measures. It is forbidden to touch the switch when wet hands or bare feet to prevent electric shock.
(9) When moving the electric pump, the power supply must be cut off, and people must not touch the water source when the electric pump is running to prevent personal accidents caused by electric leakage.
(10) It is strictly prohibited to operate the motor without phase. If the fuse is found to be blown, the reason should be checked before continuing to use. Do not thicken the fuse arbitrarily.
(11) When the pump is running, it should be managed by a specially assigned person. If any abnormality is found, it should be stopped immediately for inspection and troubleshooting.
(12) After the electric pump operates normally for half a year under the specified working medium conditions, the sealing condition of the oil chamber shall be checked. If the oil in the oil chamber is emulsified or there is water precipitation, the # 10-20 mechanical oil and mechanical seal shall be replaced in time. The electric pump used under severe working conditions shall be frequently overhauled.
(13) The user should select the appropriate flow head according to the actual operating conditions to achieve the best use effect. The parameters shown on the pump nameplate or manual are the best operating conditions.

Troubleshooting of sewage pump
Causes and treatment methods of 6 common faults of sewage pump:
1. The sewage pump cannot be started automatically.
Causes: ① The floating ball is stuck and cannot float or the wire is too long; ② Power failure.
Treatment method: ① move the floating ball or shorten the conductor; ② contact the maintenance personnel for treatment.
2. The sewage pump will not drain after starting.
Causes: ① check valve is blocked; ② pipe is blocked; ③ impeller is blocked.
Treatment method: ① dredge the check valve to remove the coal accumulated in the pit; ② dredge the pipeline to remove the coal accumulated in the pit.
3. The sewage pump vibrates greatly during operation.
Causes: ① wear caused by impeller imbalance; ② low water level, air entering.
Treatment method: ① Replace the impeller; ② Stop the pump and wait until the water level is high.
4. The lift of sewage pump is not enough.
Causes: ① The clearance between the impeller and the guard plate is too large; ② The impeller is blocked.
Treatment method: ① Adjust the clearance, or replace the impeller and guard plate; ② Clean the impeller.
5. The bearing of sewage pump is overheated.
Causes: ① too little or too much lubricating oil; ② impurities in the oil; ③ bearing wear.
Treatment method: ① keep the lubricating oil at the normal oil level; ② replace the lubricating oil; ③ replace the bearing.
6. The sewage pump cannot stop automatically.
Causes: ① The floating ball is stuck on the water surface or the wire is too long; ② The coal on the electrode rod is connected to the tank wall; ③ Power failure.
Treatment method: ① move the floating ball or shorten the conductor; ② remove the coal accumulated on the rod; ③ contact the maintenance personnel for treatment.

How to select the right pump?

The following factors need to be considered when selecting the correct pump:

Flow demand: Determine the flow range of the required pump to meet the specific application requirements.
Head requirements: determine the head requirements of the required pump to ensure that the medium can be transported to a specific height or distance.
Media properties: understand the properties of the transported media, including temperature, density, viscosity, corrosivity, etc., to select suitable pump data and types.
Operating conditions: consider the operating conditions such as ambient temperature, altitude, operating time and reliability to ensure that the selected pump can operate normally under these conditions.
Energy efficiency: select high-efficient pumps to save energy and reduce costs.
Maintenance and repair: consider the maintenance and repair needs of the pump to ensure that the selected pump is easy to maintain and repair.

Considering the above factors comprehensively, selecting a pump suitable for a specific application can improve the efficiency and reliability of the system and reduce the operating cost.

Pump Selection Guide

1. Make the type and performance of the selected pump meet the requirements of process parameters such as device flow, head, pressure, temperature, cavitation flow, suction head, etc.
2. Must meet the requirements of medium characteristics。
For pumps conveying flammable, explosive, toxic or valuable media, reliable shaft seals or leak free pumps are required, such as magnetic drive pumps, diaphragm pumps, mask pumps。
For pumps conveying corrosive media, it is required to use corrosion resistance data for convection parts.
For pumps conveying medium containing solid particles, the convection parts shall be made of wear-resistant materials, and the shaft seal shall be flushed with clean liquid when necessary.
3. High mechanical reliability, low noise and low vibration.
4. Economically, the total cost of equipment cost, operation cost, maintenance cost and management cost shall be the lowest.
5. The centrifugal pump has the characteristics of high speed, small volume, light weight, high efficiency, large flow, simple structure, no pulsation in infusion, stable performance, easy operation and maintenance.
Therefore, centrifugal pump shall be selected as far as possible except for the following situations:

a. The metering pump shall be selected when there are metering requirements.
b. Reciprocating pump can be selected when the head requirement is very high, the flow is very small, and there is no suitable small flow high head centrifugal pump available. Vortex pump can also be selected if the cavitation requirement is not high.
c. When the head is very low and the flow is very large, axial flow pump and mixed flow pump can be selected.
d. When the medium viscosity is large (more than 650~1000mm2/s), rotor pump or reciprocating pump (gear pump, screw pump) can be considered.
e. When the medium air content is 75%, the flow is small and the viscosity is less than 37.4mm2/s, vortex pump can be selected.
f. For occasions with frequent startup or inconvenient pump filling, pumps with self-priming performance should be selected, such as self-priming centrifugal pumps, self-priming vortex pumps, pneumatic (electric) diaphragm pumps.

Basis for pump selection: five aspects should be considered according to the process flow and water supply and drainage requirements, including liquid delivery capacity, device lift, liquid property, pipeline layout and operating conditions.

1. Flow is one of the important performance data for pump selection, which is directly related to the production capacity and delivery capacity of the whole plant. For example, the design institute can calculate the normal, minimum and maximum flow of the pump in the process design. When selecting the pump, the maximum flow is taken as the basis, taking into account the normal flow. When there is no maximum flow, 1.1 times of the normal flow is usually taken as the maximum flow.
2. The head required by the device system is another important performance data for pump selection, which is generally selected by enlarging the head after 5% – 10% allowance.
threeLiquid properties include liquid medium name, physical properties, chemical properties and other properties. Physical properties include temperature c, density d, viscosity u, solid particle diameter and gas content in the medium. This involves system head, calculation of effective cavitation allowance and appropriate pump type: chemical properties mainly refer to chemical corrosivity and toxicity of liquid medium. Pump data and selectionImportant basis for which type of shaft seal to use.
4. The pipeline layout condition of the device system refers to some data such as the height of liquid delivery, the distance between liquid delivery and the direction of liquid delivery, the lowest liquid level on the suction side, the highest liquid level on the discharge side, as well as pipe specifications and their lengths, data, pipe fitting specifications, quantities, etc., so as to calculate the system head and check the NPSH.
5. There are many operating conditions, such as liquid operation T saturated steam force P, suction side pressure PS (absolute), discharge side vessel pressure PZ, altitude, ambient temperature, whether the operation is intermittent or continuous, and whether the pump position is fixed or movable.

According to the pump selection principles and basic conditions, the specific operations are as follows:
1. Horizontal, vertical and other types of pumps (pipeline type, submersible type, submerged type, non clogging type, self-priming type, gear type, etc.) shall be selected according to the layout, terrain conditions, water level conditions and operating conditions of the device.
2. According to the nature of liquid medium, determine whether the clean water pump, hot water pump or oil pump, chemical pump or corrosion resistant pump or impurity pump, or use the non clogging pump.
3. Determine the menu suction pump or double suction pump according to the flow; select single stage pump or multi-stage pump according to the lift, high speed pump or low speed pump (air conditioning pump), multi-stage pump efficiency is lower than single stage pump, if both single stage pump and multi-stage pump can be used, first select single stage pump.
4. Determine the specific model of the pump
After determining the series of pumps to be selected, the main parameters of the two performances, namely the head after amplification of 5% – 10% margin, can be taken according to the maximum flow (when there is no maximum flow, 1.1 times of the normal flow is usually taken as the maximum flow), and the specific model can be determined on the type spectrum or series characteristic curve. The operation is as follows:
Use the pump characteristic curve to find the required flow value on the abscissa and the required head value on the ordinate. From the two values, draw the vertical line or horizontal line upward and to the right, and the intersection point of the two lines just falls on the characteristic curve, then the pump is the pump to be selected. However, this ideal situation is rarely seen, and the following two situations usually occur:

First, the intersection point is above the characteristic curve, which means that the flow meets the requirements, but the head is not enough. At this time, if the head difference is not much, or about 5%, it can still be selected. If the head difference is much, select the pump with a larger head. Or try to reduce the pipeline resistance loss.
Second, the intersection point is below the characteristic curve, within the sector trapezoid range of the pump characteristic curve, the model is initially determined, and then the impeller diameter is cut according to the difference in head,If the head difference is very small, do not cut. If the head difference is very large, cut the impeller diameter according to the required Q, H, and according to its ns and cutting formula. If the intersection point does not fall within the range of the fan-shaped trapezoid, select the pump with a small head. When selecting the pump, sometimes consider the production process requirements and select Q-H characteristic curves of different shapes.

5. After the pump model is determined, if the pump or the physical and chemical medium of the transmission medium is similar to water, it is necessary to go to the relevant product catalog or sample, and correct it according to the performance table or performance curve of the model to see whether the normal working point falls in the priority working area of the pump, and whether the effective NPSH is greater than (NPSH). In turn, the geometric installation height can be corrected with NPSH.
6. For liquid pumps conveying viscosity greater than 20 mm2/s (or density greater than 1000 kg/m3), the characteristic curve of water test pump must be converted into the performance curve of the viscosity (or density), especially the suction performance and input power must be carefully calculated or checked.
7. Determine the number of pumps and standby rate:

a. Generally, only one pump is used for normal operation, because one large pump is equivalent to two small pumps working in parallel, (meaning that the head and flow are the same), and the efficiency of the large pump is higher than that of the small pump, so from the perspective of energy conservation, it is better to choose one large pump instead of two small pumps, but in the following cases, the parallel cooperation of two pumps can be considered: the flow is large, and one pump can not reach this flow.
b. For large pumps that need 50% standby rate, two smaller pumps can be used, one for standby (three in total).
c. For some large pumps, pumps with 70% flow requirements can be selected for parallel operation without standby pumps. When one pump is overhauled, the other pump still undertakes 70% of the transportation in production.
d. For pumps that need to operate continuously for 24 hours, three pumps shall be standby, one for operation, one for standby and one for maintenance.

8. Generally, customers can submit their “basic conditions for pump selection”, and our company will select the pump or recommend better pump products. If the design institute has determined the pump model when designing the device and equipment, the pump shall be configured according to the requirements of the design institute.

Pump maintenance

The pump is one of the indispensable and important equipment of the enterprise. Affected by the working conditions, corrosion, cavitation, erosion, wear and other phenomena often occur, leading to equipment failure. The enterprise can only invest a lot of money to purchase new pumps, but a large number of parts are reported, resulting in a large waste of money. The design and manufacture of domestic pumps are basically in accordance with the “metal”The idea is to use stainless steel and carbon steel data as the main pump body data. In the face of high corrosion and strong scouring environment, high nickel alloy is required, and even excellent corrosion resistant data such as titanium, zirconium and tantalum are used. These rare metal materials are expensive and have a large price fluctuation, and the high manufacturing cost and complex manufacturing process cause the price of such pumps to be expensive, usually tens of thousands toMillions of different types of pumps also result in high procurement costs. With the development of international advanced pump body research and the application of new material pump bodies, domestic scientific research institutions learn from the development ideas of western developed countries on pump body research. A few domestic enterprises and institutions have begun to develop inorganic non-metallic materials such as ceramics, glass fiber reinforced plastics, graphite and carbon products, and synthetic organic polymer materials such asPlastic, glass fiber or carbon fiber reinforced engineering plastics, etc. The development trend of these domestic pumps catered to the international trend, and soon achieved good results in domestic use.
It is through the effective solution of such details that the advantages of low production costs and strong competitiveness of European, American, Japanese and Korean enterprises are realized. While domestic enterprises continue to introduce advanced equipment and hire managers with high salaries, they ignore such details of daily equipment management. They only reduce costs by reducing workers’ salaries, welfare benefits and other measures, resulting in workers’ laborLow motivation and chaotic management are inevitable.
It is obvious that the use of such data has greatly reduced the production cost, no need to purchase high-value metals, no need for special equipment and professionals to make, and it has good use effect, longer life, and simpler repair. Its huge advantages are far beyond the traditional pump body data. The application of new pump body materials has greatly reduced the pump body data costs and maintenance costs.
Matters needing attention
During the operation of the pump, the water flowing in the pump is affected by the friction between the pump and the surface of the flow channel and the pump impeller, as well as the viscosity of the water itself. The energy consumed by the pump is mainly used to resist the flow friction and vortex resistance of the water surface. The energy consumed by the water in the flow process (head loss)It is used to overcome internal friction and friction between water and equipment interface. If the surface of pump and impeller is smooth (this surface is called hydraulic smooth surface)The surface resistance is small, and the energy consumption is small. Spray polymer materials on the pump flow surface and impeller to form a hydraulically smooth surface. The surface finish of the ultra smooth surface coating is 20 times that of the polished stainless steel. This extremely smooth surface reduces the stratification of the fluid in the pump, thus reducing the turbulence inside the pump, reducing the volume loss and hydraulic loss in the pumpThe power consumption is reduced to reduce the water flow resistance loss, so as to improve the hydraulic efficiency of the pump, and to a certain extent, the mechanical efficiency and volumetric efficiency can also be improved. The density of the molecular structure of the coating can isolate the contact between the air, water and other media and the base material of the pump impeller, and minimize the electrochemical corrosion and corrosion. In addition, the essence of the polymer composite material is polymerThe polymer, with chemical corrosion resistance, can improve the corrosion resistance of the pump and greatly enhance the pump’s resistance to erosion and corrosion. Because of its good wear resistance and impact resistance, it can play a very good role in wear resistance and buffering when fine solid particle media contact and impact the pump.
It is suggested that industrial enterprises should apply this composite coating to deal with and extend the service life of the pump, achieve long-term effectiveness of the pump efficiency, and avoid many impacts on production, cost, labor force, etc. due to frequent replacement. Energy saving and consumption reduction of the pump should continue to explore under the condition of combining theory with practice, boldly introduce new technologies, and find more reasonable and economic energy saving measures. High scoreThe sub composite material is simple and convenient to operate, has low requirements for the construction environment, and can be widely popularized and applied. The surface smoothness of such data is stronger than that of polished stainless steel, and has hydrophobicity and anti algae adhesion. After completion, the equipment surface will form a hydraulic smooth surface, thus improving the operating efficiency of the pump and achieving remarkable energy saving effect. At the same time, it can also improve the internal surface of the pumpThe surface is protected against corrosion, which has dual effects of energy conservation and corrosion prevention. The use, maintenance and repair of the pump will play a key role in saving energy and reducing consumption and improving economic benefits.

Troubleshooting the pump

1. The water pump does not rotate after starting?

Causes: the packing is too tight or the impeller and pump body are blocked by sundries; the pump shaft, bearing and leakage ring are rusted; the pump shaft is severely bent.
Troubleshooting: loosen the packing and dredge the water channel: disassemble the pump body to remove debris or rust; correct the bent shaft or replace the pump shaft. When starting, the pump does not rotate, but there is a buzz. In addition to the above reasons, it is also necessary to check whether the motor circuit is lack of phase or voltage, and the pump is overloaded.

2. The water pump does not discharge water after starting?

Cause: There is air in the pump or air accumulates in the water inlet pipe, the bottom valve is not closed tightly enough to fill water, the vacuum pump filler has serious air leakage, the gate valve or flap valve is not closed tightly, the dynamic water level is lower than the pump filter pipe, the suction pipe is broken, etc.
Troubleshooting: remove the sundries, replace the damaged rubber pad, change the direction of the valve plate, press or replace the new packing, close the gate valve or flap valve, increase the tank water volume until there is no bubble at the vent plug; replace the cracked pipe water, reduce the head, and press the pump nozzle 0.5m below the water level. Lower the installation position of the pump so that the filter pipe is below the dynamic water level or the equivalent dynamic water levelLift the filter pipe and then pump water; repair or replace the suction pipe.

Insufficient flow?

Cause: The actual demand head of the pipeline exceeds the allowable head of the water pump; the rotational speed is not matched or the belt slips, the rotational speed is low, the installation angle of the axial flow pump blade is too small, the suction head is too high, the bottom valve, pipeline and impeller are partially blocked or the impeller is too worn, the suction height exceeds the standard, and the water outlet pipe leaks seriously. The suction pipe leaks air, the bottom valve leaks air, the water inlet is blocked, and the water inlet depth of the bottom valve is insufficient.
Troubleshooting: reduce the lift, restore the rated speed, remove the belt dirt and adjust the belt tightness, adjust the blade angle, lower the installation position of the water pump, tighten the gland, seal the water leakage of the water pump, compress the packing or replace the packing, remove the blockage, replace the impeller, replace the leakage ring, block the leakage place, check the suction pipe and bottom valve, block the leakage source, and clean the silt at the water inletOr blockage, the water inlet depth of the bottom valve must be greater than 1.5 times the diameter of the water inlet pipe. Increase the water inlet depth of the bottom valve, check the power supply voltage, increase the pump speed, replace the seal ring or impeller, reduce the installation position of the pump, or replace the water inlet depth of the high lift bottom valve, check the power supply voltage, increase the pump speed, replace the seal ring or impeller, reduce the installation position of the pump, or replace the high lift bottom valveHead pump.

How to select the correct pump manufacturer?

The following aspects need to be considered when selecting the correct pump manufacturer:

Application requirements: first of all, you need to know the pump’s use, flow, head, pressure and other parameters, as well as the medium the pump handles, which will help determine the appropriate pump type.
Quality and reliability: To select a pump manufacturer with a good reputation and history, you can view its product certification and quality assurance measures, such as ISO certification and quality assurance standards.
Technical support and after-sales service: select a manufacturer that can provide technical support and after-sales service in order to get support and help when needed.
Price and cost performance: Of course, price is also one of the factors to be considered. When choosing appropriate quality and service, we should also consider the cost performance of products to ensure that we will not pay too high a price.

Considering the above factors, choose the one that suits your needs pump manufacturer, which can not only improve the operating efficiency of equipment, but also improve the reliability of equipment and reduce operating costs. . .

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