The use difference between butterfly valve and gate valve
Gate valves and butterfly valves are used in the pipeline to switch and regulate the flow. Of course, there are some methods in the selection process of butterfly valve and gate valve.
In the water supply network, in order to reduce the re soil depth of pipelines, butterfly valves are generally selected for larger diameter pipelines, which have little impact on the re soil depth. Gate valves of the same specifications are more expensive than butterfly valves. As for the demarcation line of diameters,consideration should be made according to the specific conditions. In terms of the use of butterfly valves in recent ten years, the failure of butterfly valves is higher than that of gate valves, so the conditions are acceptable However, it is worthy of attention to expand the application scope of gate valve.
In recent years, many domestic valve manufacturers have developed and imitated soft seal gate valves. Compared with traditional wedge or parallel double gate plate gate valves, this kind of gate valve has the following characteristics:
- The valve body and valve cover of soft seal gate valve are cast by precision casting method. They are formed at one time without mechanical processing or using copper sealing ring, so as to save non-ferrous metals.
- There is no pit at the bottom of the soft seal gate valve, no slag deposit, and the failure rate of the gate valve is low.
- Soft seal rubber lined valve plate has uniform size and strong interchangeability.
Therefore, the soft seal gate valve will be a form that the water supply industry is willing to adopt. At present, the diameter of the soft seal gate valve manufactured in China is 1500mm, but the diameter of most manufacturers is between 80-300mm. There are still many problems in the domestic manufacturing process. The key component of the soft seal gate valve is the rubber lined valve plate, and the technical requirements of the rubber lined valve plate are higher, which can not be achieved by all foreign manufacturers. We always buy and assemble from reliable manufacturers.
The copper nut block of soft seal gate valve in China is embedded above the rubber lined valve plate, which is similar to the structure of gate valve. Due to the movable friction of the nut block, the rubber lining of the valve plate is easy to peel off. For the soft seal gate valve of a foreign company, the copper nut block is embedded in the rubber lined gate plate to form a whole, which overcomes the above shortcomings, but the concentricity of the combination of valve cover and valve body is high.
However, when opening and closing the soft seal gate valve, it should not be closed too tightly, as long as the sealing effect is achieved, otherwise it is not easy to open or the rubber lining is peeled off. A valve manufacturer uses the torque wrench to control the closing degree during the pressure test of the valve, and the valve operator of the water supply company should also follow this method.
What is the use difference between butterfly valve and gate valve?
According to the function and application of gate valve and butterfly valve, the gate valve has small flow resistance and good sealing performance. Because the flow direction of gate valve plate and medium is vertical, if the gate valve is not opened and closed in place on the valve plate, the erosion of medium on the valve plate will make the valve plate vibrate, and the seal of gate valve will be easily damaged.
Butterfly valve, also known as flap valve, is a simple structure control valve, which can be used for low-pressure pipeline medium on-off control. Butterfly valve refers to a kind of valve whose closing piece (disc or butterfly plate) is a disc and rotates around the valve shaft to open and close. The valve can be used to control air, water, steam, various corrosive media, mud, oil, liquid metal and radioactive media Flow of fluid. In the pipeline, it mainly plays the role of cutting off and throttling. The opening and closing part of butterfly valve is a disc-shaped butterfly plate, which rotates around its own axis in the valve body, so as to achieve the purpose of opening, closing or regulating.
The butterfly plate is driven by the valve stem. If it is turned by 90 degrees, it can open and close once. The flow of medium can be controlled by changing the deflection angle of the butterfly plate.
Difference between working condition and medium
Butterfly valve is applicable to the pipeline conveying various corrosive and non corrosive fluid medium in the engineering system of generator, gas, natural gas, liquefied petroleum gas, city gas, cold and hot air, chemical smelting and power generation, environmental protection, building water supply and drainage, etc., which is used to regulate and cut off the flow of medium.
Gate valve is a kind of gate valve. The movement direction of gate valve is perpendicular to the fluid direction. Gate valve can only be fully opened and fully closed. The unsuitable parameters of gate valve are different, usually 5 ° and 2 ° 52 ‘when the medium temperature is not high. This kind of gate valve is called elastic gate to improve its processability and make up for the deviation of sealing surface angle during processing.
When the gate valve is closed, the sealing surface can only rely on the medium pressure to seal, that is, only rely on the medium pressure to press the sealing surface of the gate valve to the seat on the other side to ensure the sealing of the sealing surface, which is self sealing. Most gate valves adopt forced sealing, that is, when the valve is closed, the gate valve should be pressed to the seat by external force to ensure the sealing of the sealing surface.
The difference of sports mode
The gate of the gate valve moves in a straight line with the valve stem, which is also called rising stem gate valve. Generally, there are trapezoidal threads on the lifting rod. Through the nut on the top of the valve and the guide groove on the valve body, the rotary movement is changed into a straight line movement, When the valve is opened, when the lifting height of the gate is equal to 1:1 of the valve diameter, the fluid channel is completely unblocked, but this position can not be monitored during operation. In actual use, the top of the valve stem is taken as the sign, that is, the position where the valve can not be opened is taken as its full open position. In order to consider the locking phenomenon of temperature change, Usually, when the valve is opened to the top position, it is turned back by 1 / 2-1 turn as the position of the full open valve. Therefore, the full open position of the valve is determined according to the position of the gate (i.e. stroke). The nut of the valve stem of some gate valves is set on the gate, and the rotation of the hand wheel drives the valve stem to rotate, so as to lift the gate. This kind of valve is called rotary stem gate valve or non rising stem gate valve.
Source: China Valve Supplier: www.epowermetals.com
(Yaang Pipe Industry is a leading manufacturer and supplier of nickel alloy and stainless steel products, including Super Duplex Stainless Steel Flanges, Stainless Steel Flanges, Stainless Steel Pipe Fittings, Stainless Steel Pipe. Yaang products are widely used in Shipbuilding, Nuclear power, Marine engineering, Petroleum, Chemical, Mining, Sewage treatment, Natural gas and Pressure vessels and other industries.)
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