May I also ask a question about differential pressure control valves? I hope everyone can help take a look.
Thread Content
There is a differential pressure control valve on site; by setting a specific pressure, it ensures that the pressure difference between the pump’s outlet and inlet remains constant. However, even though the differential pressure value has been set correctly, the pressure at the pump’s outlet continues to fluctuate significantly. Observing the control valve shows that its opening also varies. If the control valve is isolated on site and the pressure at the pump’s outlet stops fluctuating, then it indicates that there is a problem with the control valve itself. So, what usually causes problems in this situation? Before, as long as the settings were correct, the pump outlet pressure remained stable; but now it keeps fluctuating without any clear reason. I hope for an explanation
Aren’t you using a self-regulating valve? ? If so, check the PID to see if it’s appropriate
For self-acting control valves and automatically controlled valves, check whether there are any leaks in the diaphragm of the valve or in the air supply. In the case of control valves, inspect the air supply to the actuator and adjust it to prevent fluctuations. If the exterior of the valve appears to be in good condition, for self-acting control valves it is possible to take them apart to examine the valve core; for automatically controlled valves, the PID parameters can be adjusted to ensure stable control
It is a control valve; when I set the differential pressure target very high (to such an extent that even with the control valve fully closed the target cannot be reached – the differential pressure is highest when it’s completely closed), theoretically the control valve should remain fully closed without any fluctuations. But in reality, there are still changes in its opening degree.
In such a case, first check whether the output force of the valve actuator is sufficient; determine what the maximum pressure at the pump outlet on site is Is it consistent with the selection? If it is too large, calculate whether the output force of the existing actuator is sufficient under such operating conditions. Secondly, when putting the control valve into use, the main controller can first switch it to manual mode, manually adjusting the pressure difference to the set value, and then switch it to automatic mode once the operating conditions are stable.