How to correctly select the valve

Determining the performance and use of the main valve, the valve belonging properties are used:
1. Types of valves ( closed-circuit valves, regulating valves, safety valves, etc.);
2 , product type (such as gate valve, cut-off Valves, butterfly valves, ball valves, etc.);
3 , the main valve parts (valve body, valve cover, stem, valve, sealing surface) materials; valve transmission methods.
Structural characteristics: It determines some of the structural characteristics of the valve installation, maintenance, maintenance and other methods, belonging to the structural characteristics are: the valve structure length and overall height, and the connection of the pipeline (flange connection, threaded connection, Clamp connection, external thread connection, welding end connection, etc.); the form of the sealing surface (inset ring, thread ring, build-up welding, spray welding, valve body); valve stem structure (rotating rod, lifting rod).
Steps for selecting the valve :
1. Identify the use of the valve in the equipment or device, determine the valve's working conditions, applicable media, working pressure, working temperature, etc.
2. Clear the nominal diameter and connection method of the pipe connected with the valve: flange, thread, welding and so on.
3 , determine the way to operate the valve: manual, electric, electromagnetic, pneumatic or hydraulic, electro-hydraulic linkage and so on.
4 , according to the pipeline conveying medium, working pressure, working temperature to determine the selected valve housing and internal parts of the material: cast steel, carbon steel, stainless steel, alloy steel, stainless steel, acid-resistant copper alloy.
5 , choose the type of valve: closed-circuit valves, regulating valves, safety valves and so on.
6 , determine the type of valve: gate valve, globe valve, ball valve, butterfly valve, throttle valve, safety valve, pressure reducing valve, steam trap and so on.
7 , determine the valve parameters: For automatic valves, according to different needs to determine the allowable flow resistance, emission capacity, back pressure, etc., and then determine the nominal diameter of the pipe and valve seat hole diameter.
8. Determine the geometric parameters of the selected valve: structure length, flange connection form and size, dimensions of the valve height direction after opening and closing, size and number of bolt holes to be connected, overall valve size, etc.
The basis for selecting the valve :
1. The purpose of the selected valve, operating conditions and operating control methods, valve specifications and categories, shall comply with the requirements of the pipeline design document, and the working pressure shall be greater than or equal to the working pressure of the pipeline.
2. The nature of the working medium: working pressure, working temperature, corrosion performance, whether it contains solid particles, whether the medium is toxic, whether it is flammable, explosive medium, viscosity of the medium, etc.
3 , the requirements of the fluid characteristics of the valve: flow resistance, discharge capacity, flow characteristics, seal rating, etc.
4. Installation dimensions and dimensions: Nominal diameter, connection to the pipe, connection size, form factor or weight limit.
5. Additional requirements for the valve's product reliability, service life, and explosion-proof performance of electrical devices. (Note when selecting parameters: If the valve is to be used for control purposes, the following additional parameters must be determined: method of operation, Large and small flow requirements, normal flow pressure drop, pressure drop when closed, and large and small inlet pressure of the valve. ) According to the above selection of valve basis and steps, reasonable and correct selection of the valve must also be a detailed understanding of the internal structure of various types of valves in order to make the right choice of valve to make the right choice. The final control of the pipeline is the valve. The opening and closing part of the valve controls the flow direction of the medium in the pipeline. The shape of the valve flow path enables the valve to have certain flow characteristics. When selecting the piping system suitable for installing the valve, it must be taken into account. at this point.