Pressure regulator valves are essentially pressure control valves but its pressure sensing/measurement is integral part of the control valve and it regulates to keep upstream or downstream pressure depending of requirements.
Upstream pressure regulator valve are pressure regulator maintaining upstream pressure. Upstream Pressure maintained by valve opening and closing with releasing fluid to maintain pressure upstream side and are presented as follows
Downstream pressure regulator are pressure regulator maintaining upstream pressure. Downstream Pressure maintained by valve opening and closing with releasing fluid to maintain pressure downstream side and are presented as follows
Generally pressure regulator valve are found in gas distributions headers, purge gas to vessels, vent line to vent/flare header, etc.
