A hydraulically operated pilot controlled modulating type pressure relief valve is design to maintain constant up stream pressure and to minimize surging.
The valve is actuated by line pressure through a pilot control system , opening fast to hold the upstream line pressure constant but closing gradually to Prevent surges. Operation is completely automatic and pressure settings may be easily changed.
Installed on a by-pass line, mainline pressure is accurately controlled by relief excess pressure. This valve can be used for pressure relief, back pressure, up stream pressure control and many more.
Installed in a mainline it prevents upstream pressure from dropping (sustain) below preset minimum.