Pressure Control Valves are generally used in the process industry to maintain the pressure of a process or utility fluid within a specified range by changing upstream / downstream flow of that fluid.
Depending on upstream or downstream process requirement, the pressure is measured and it send signal to controller. Â Controller compares the reading and gives inputs to throttle (open or close) the control valve.
Generally pressure control valve are found in the vapor outlet of separator, pump discharge line, pump return / kickback line, Fuel gas inlet of fired heaters, vent line to vent/flare header, etc.