PRESSURE RELIEF VALVE WITH ORIFICE

摘要

A pressure relief valve includes a housing including an inlet chamber adapted to be in communication with an outlet of a pump and an outlet chamber adapted to be in communication with a pump inlet. The housing includes a bore having a first end in communication with the inlet chamber and a main spill aperture in communication with the bore and the outlet chamber. A piston includes an orifice and an axially spaced apart aperture. The piston is axially moveable within the bore between a first position whereat the piston seals the inlet chamber from the outlet chamber, a second position whereat the inlet and outlet chambers are in fluid communication with one another via only the orifice, and a third position whereat the inlet and outlet chambers are in fluid communication with one another via the orifice and the aperture. A spring biases the piston toward the first position.