Valve characteristics and selection

Valves generally have two characteristics: service characteristics and structural characteristics.
1 Usage Characteristics
It determines the main performance and range of use of the valve, including:
Valve type (closed valve, Regulating Valve, safety valve, etc.);
Product type (Gate Valve, Globe Valve, Butterfly Valve, Ball Valve, etc.);
Main parts of the valve (valve body, valve cover, stem, valve plate, sealing surface);
Valve transmission mode, etc.
2 Structural Characteristics
It determines some structural characteristics of the valve, installation, repair, maintenance and other methods, including:
The structural length and overall height of the valve and the connection form with the pipe (flange connection, thread connection, clamp connection, external thread connection, welding end connection, etc.);
Sealing surface form (insert ring, thread ring, surfacing welding, spray welding, valve body);
Valve stem structure form (rotary rod, lifting rod), etc.

Selection step
(1) Clear the purpose of the valve in the equipment or device, determine the working conditions of the valve: applicable media, working pressure, working temperature, etc.
(2) Determine the nominal diameter and connection mode of the pipeline connected with the valve: flange, thread, welding, etc.
(3) Determine the operation mode of the valve: manual, electric, electromagnetic, pneumatic or hydraulic, electrical linkage or electro-hydraulic linkage, etc.
(4) The shell and internal materials of the selected valve should be determined according to the medium, working pressure and working temperature of the pipeline: gray cast iron, malleable cast iron, ductile cast iron, carbon steel, alloy steel, stainless steel acid resistant steel, copper alloy, etc.
(5) Select the type of valve: closed valve, regulating valve, safety valve, etc.
(6) Determine the valve types: Gate valve, globe valve, ball valve, butterfly valve, throttle valve, safety valve, pressure reducing valve, trap valve, etc.
(7) Determine the parameters of the valve: for automatic valves, determine the allowable flow resistance, discharge capacity, back pressure, etc., according to different needs, and then determine the nominal diameter of the pipeline and the aperture of the seat.
(8) Determine the geometric parameters of the selected valve: structural length, flange connection form and size, valve height direction after opening and closing size and number of connecting bolt holes, valve overall size, etc.
(9) Use existing data: valve product catalog, valve product samples, etc., to select appropriate valve products.