Valve Choosing And Valve Flow Characteristics

The shape of the valve opening and closing parts and the valve flow channel make the valve have certain flow characteristics. This must be taken into consideration when choosing a valve.

(1) Valve for cutting off and connecting the medium

Usually choose a valve with a small flow resistance and a straight-through flow path. Such valves include gate valves, stop valves, and plunger valves. The downward-closed valve has a higher flow resistance than other valves due to the tortuous flow path, so it is rarely used. However, in situations where higher flow resistance is allowed, closed valves can also be used.

(2) Valves for flow control

Usually choose a valve that is easy to adjust the flow rate. Such as regulating valve or said control valve, throttle valve, plunger valve, because its valve seat size is proportional to the stroke of the opening and closing parts. Rotary (such as plug valves, ball valves, butterfly valves) and flex (pinch valves, diaphragm valves) valves can also be used for throttling control, but they are usually only applicable within a limited range of valve diameters. In most cases, people usually change the valve flap shape of the shut-off valve for throttling. It should be pointed out that it is extremely unreasonable to change the opening height of the gate valve or stop valve to achieve throttling. Because the flow rate of the medium in the pipeline is high under the throttle shape, the sealing surface is easily eroded and worn, and the cut-off sealing effect is lost. Similarly, it is unreasonable to use a throttle valve as a cut-off device.

(3) Valve for reversing and shunting

According to the reversing and shunting needs, this valve can have two or more channels, which is suitable for the selection of plug valves and ball valves. Most valves used for reversing and shunting use this type of valve. In some cases, other types of valves, which are properly connected to each other with two or more valves, can also be used for reversing and dividing the medium.

(4) Valves for media with suspended particles

If the medium has suspended particles, it is most suitable to use a valve with a wiping effect along the sealing surface of its opening and closing parts, such as a flat gate valve.