The principle of selecting the valve

The valve opening and closing part controls the flow of the medium in the pipe. The shape of the valve flow path allows the valve to have a certain flow characteristic. This must be taken into consideration when selecting the door.

1. The valve flow channels of cut-off and open media are straight-through valves with small flow resistance, and are usually selected as the valves used for shut-off and open media. Down-closed valves are less preferred due to their serpentine flow paths and higher flow resistance than other valves. Closed-type valves, such as globe valves and column valves, are used where higher flow resistance is tolerated.

2. Valves for controlling the flow rate Usually, the valves that are easy to adjust the flow rate are used as control flow. The down-closed valve is suitable for this purpose, because its valve seat size is directly proportional to the stroke of the closing member. Rotary valves (plug valves, ball valves, butterfly valves) and flexible valve body valves (pinch valves, diaphragm valves) can also be used for throttling control, but they are generally only suitable for limited valve diameters. The gate valve is a cross-cut movement of a circular valve seat with a disk-shaped gate. It can control the flow only when it is close to the closed position, so it is usually not used for flow control.

3. Valves with reversing diversion The valve may have three or more channels depending on the need for reversing the diversion. Plug valves and ball valves are more suitable for this purpose, so most of the commutating diverted valves use one of these valves. However, in some cases, other types of valves can also be used as commutation diverters as long as two or more valves are properly connected.

4. Valves for media with suspended particles When the medium contains suspended particles, it is best to use its closing element to slide the valve with the wiping action along the sealing surface. If the closing member's back and forth movement of the valve seat is vertical, then it is possible to hold the particles, so this valve is only used for basic cleaning media unless the sealing surface material can allow embedding of particles. The ball valve and the plug valve wipe the seal during the opening and closing process, so it should be used in the medium with suspended particles.