What are the selection criteria for valves

Valve selection criteria: Multi dimensional consideration to ensure system compatibility

Valve selection should take into account multiple factors to meet the requirements of safe, stable, and efficient operation of the system. The key selection criteria are as follows:

1.fluid characteristics

·Fluid type: In gases, general gases can choose gate valves, globe valves, etc; Combustible and explosive gases should be selected with good sealing and fire and explosion resistance, such as ball valves with fire-resistant structures. In terms of liquids, there are various choices of clean water; For liquids containing solid particles, wear-resistant valves such as plug valves should be selected to prevent wear and blockage; Corrosive liquids require valves made of corrosion-resistant materials, such as stainless steel and plastic valves, depending on the medium.

·Fluid temperature: High temperature fluids (above 450 ℃) should choose high-temperature resistant valves, such as chromium molybdenum steel high-temperature gate valves used in steam pipelines. Low temperature fluids (below -40 ℃) require valves with good low-temperature toughness, and low-temperature ball valves are commonly used in liquid nitrogen and liquid oxygen pipelines.

·Fluid pressure: For low-pressure fluids (less than 1.6MPa), ordinary pressure grade valves can be selected; High pressure fluids (medium pressure 1.6-10MPa, high pressure greater than 10MPa) require the use of high-pressure valves, such as high-pressure shut-off valves.

·Fluid viscosity: Low viscosity fluids have a wide range of selection options; High viscosity fluids are prone to adhesion and blockage, so it is necessary to choose gate valves and ball valves with high flow capacity and low blockage. If necessary, electric or pneumatic actuators should be used.

2.Process function

·Cut off function: Gate valves have low fluid resistance, easy opening and closing, and are suitable for large-diameter pipelines; The shut-off valve is well sealed and suitable for occasions with high sealing requirements; The ball valve switches quickly and seals reliably, suitable for frequent opening and closing; Butterfly valves have a simple structure and small volume, making them suitable for large-diameter low-pressure pipelines.

·Adjustment function: When flow and pressure need to be adjusted, a regulating valve can be used to automatically adjust the opening according to the control signal, achieving precise control. There are types such as single seat, double seat, and sleeve regulating valves.

·Check function: Check valve for preventing fluid backflow, lift check valve with good sealing but high fluid resistance, suitable for small-diameter vertical installation pipelines; Swing check valves have low fluid resistance and are suitable for large diameter horizontal installation pipelines.

·Safety protection function: The safety valve prevents equipment or pipeline pressure from exceeding the specified value, and automatically opens to discharge fluid when the pressure is too high; A bursting disc is a disposable safety device that ruptures and releases fluid when the pressure reaches the bursting value.