Valve selection guide and selection basis
At present, there are more and more valves on the market, the types of valves are particularly complex, and the structures and materials are also different. The selection of valves is crucial to the long-term operation of the device in the working conditions. Improper selection of valves and users’ lack of understanding of valves are the sources of accidents and safety threats. However, in today’s social industry, the demand for valve products is becoming more and more extensive, and users should have a further understanding and cognition of valve and other knowledge.
There are generally two kinds of Valve characteristics, use characteristics and structural characteristics.
Operating characteristics: it determines the main operating performance and scope of use of the valve, and those that belong to the operating characteristics of the valve are: the category of the valve (closed-circuit valve, regulating valve, safety valve, etc.); product Types (gate valve, stop valve, butterfly valve, ball valve, etc.); The main parts of the valve (valve body, valve cover, valve stem, valve flap, sealing surface) material valve transmission mode, etc.
Structural characteristics: it determines the structural characteristics of Valve installation, repair, maintenance and other methods. The structural characteristics are: the structural length and overall height of the valve, connection form with pipe (flange connection, thread connection, clamp connection, external thread connection, welding end connection, etc.); Form of sealing surface (Inlay, thread ring, overlaying, spraying welding, body of valve body); Structural form of valve stem rotating rod, lifting rod) etc.
Selection steps of valve:
- 1. Specify the use of the valve in the equipment or device, and determine the working conditions of the valve: applicable medium, working pressure, working temperature, etc.
- 2. Determine the nominal diameter and connection method of the pipe connected with the valve: flange, thread, welding, card sleeve, quick installation, etc.
- 3. Determine the mode of operating the valve: manual, electric, electromagnetic, pneumatic or hydraulic, electrical linkage or electro-hydraulic linkage, etc.
- 4. Determine and choose the shell of the valve and the inner parts according to the medium transported by the pipeline, working pressure and working temperature gray cast iron, malleable cast iron, ductile cast iron, carbon steel, alloy steel, stainless acid-resistant steel, copper alloy, etc.
- 5 select the types of valves: Closed-circuit valves, regulating valve, safety valves, etc.
- 6. Determine the type of valve: gate valve, stop valve, ball valve, butterfly valve, throttle valve, safety valve, pressure reducing valve, steam trap valve, etc.
- 7. Determine the parameters of the valve: for the automatic valve, according to different needs, first determine the allowable flow resistance, discharge capacity, back pressure, etc., and then determine the nominal diameter of the pipeline and the diameter of the valve seat hole.
- 8. Determine the geometric parameter structure length of the selected valve, flange connection form and size, the size of the height direction of the valve after opening and closing, the size and quantity of the connected bolt holes, the exterior dimensions of the whole valve, etc.
- 9. Use the existing information, such as product catalog of valves and product samples of valves, etc. to select appropriate valve products.
The selection basis of valve:
- 1. The purpose, working condition and control mode of the selected valve.
- 2. Nature of the working medium working pressure, working temperature, corrosion performance, whether it contains solid particle medium, whether it is toxic, whether it is the viscosity of flammable and explosive medium, etc.
- 3. Requirements for valve fluid characteristics: flow resistance, discharge capacity, flow characteristics, sealing grade, etc.
- 4. Installation size and outer size requirements: nominal diameter, connection method and connection size with the pipe, outer size or weight limit, etc.
- 5. Additional requirements for the reliability, service life and explosion-proof performance of electric devices of valve products. (Attention should be paid when parameters are selected: if the valve is to be used for control purposes, the following additional parameters must be determined: Operation method, maximum and minimum flow requirements, normal flow pressure drop, pressure Drop when closed, maximum and minimum inlet pressure of valve.)
According to the above basis and steps for selecting valves, the internal structure of various types of valves must be understood in detail when selecting valves reasonably and correctly, so as to make the right choice for the preferred valves. The final control of the pipeline is the valve. The valve hoist controls the medium in the pipeline flow way the shape of the valve passage makes the valve have certain flow characteristics, which must be taken into account when choosing the most suitable valve for installation in the pipeline system.
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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