Conditions for control valves or on/off valves
Thread Content
When specifying control valves or on-off valves, important parameters include valve pressure, pressure downstream of the valve, and the pressure difference when the valve is closed. Should these pressures be based on the most extreme operating conditions, or are normal operating conditions sufficient?
It is recommended to post the problem you want to solve for discussion. Other issues that may arise will be addressed as well. For reference. Oh, I’m not sure whether it’s for procurement or for process design.
The design pressure of the valve body is the same as that of the pipeline; more specifically, it is the same nominal pressure PN/LBS, although it can also be higher. By cutting off the differential pressure, what is being tested is the capability of the valve core and the actuator, based on the pressure at the pump’s shut-off point or the design pressure of that section of pipeline. The on-off valve is full-bore, so no flow conditions need to be specified. The differential pressure of the control valve is used to calculate the valve diameter; generally, data on the combination of pressure/differential pressure/flow rate under the maximum operating condition/normal operating condition (referring to the material balance point) are provided. Control valves are designed to serve operating conditions.
It’s best to list both the normal and extreme values
To calculate the control valve, it is necessary to provide the pressure drop in the piping system when the valve is fully open, as well as the pressure difference before and after the valve is closed. It is recommended to take a look at Zhou Hongyi’s paper on determining the pressure difference of control valves
Both extreme operating conditions and normal operating conditions must be provided