Behavior of Pilot Operated Pressure Regulating Valve


Thread Starter

Heungyong Park

First, what happens to pilot operated self regulating valve if upstream pressure decreases below setting pressure?

As far as I know, to compensate the flow in downstream, PRV moves to open position when the downstream pressure reduces. However, if the upstream pressure reduces and accordingly downstream pressure reduces, what would happen to PRV? Maybe, firstly, it starts to open.

However, if the upstream pressure is similar to or reduces and then lower than setting pressure, it would be closed or opened? From a common sense point of view, it shall be in full open position. However, because it's self-regulating valve, it could not be opened.

Second, is there any self regulating valve which opens fully when upstream is below setting pressure?