A pinch flow valve has different flow characteristics that depend on its design and body construction. The pinch valve flow characteristics determine the flow of the amount of media through its bore when the valve opens. This allows you to calculate how much material will flow out within a specific duration from the valve. Using this information, you will be able to better control the choke/throttle of the pinch valve. For effectively managing the amount of flow, it can be a good idea to equip the pinch valve with a proportional pressure regulator to partially close the rubber liner when the media is passing through.
The importance of pinch valve flow characteristics
The flow characteristic plays an important role in determining the relationship between the valve stroke and the flow coefficient. The flow coefficient of a pinch valve is defined as the number of gallons of fluid passing through in one minute at 60F with a pressure drop of 1psi at a specified opening across the valve.
It helps the manufacturers determine the accurate size of the valve opening to pass with the required flow rate of the fluid, and also to have stable control of the flow system.
The flow coefficient for each state of matter is different and mostly depends on the pressure drop across the pinch valve. For liquids, it can be calculated using the formula:
Cv= q/Fp v (G/?P)
If the value of Cv is too high, it means that the valve is too big for the required flow rate, and hence will result in wastage as well as will be difficult to control. Some issues may also arise with a large Cv in throttling because of the operator’s lack of control over the openings. In contrast, if the value is too small, it indicates that the valve is undersized. It may also result in a relatively higher pressure drop which may cause flashing or cavitation.
For more information please see pinch valve flow characteristics.