Patent ID: 7275559

Claim:
A pressure control valve including: an inlet; an outlet; a valve body between the inlet and the outlet; a chamber in fluid communication with the inlet via at least one aperture, the chamber being formed by connection of the inlet to the valve body; a piston having opposed smaller and larger ends each having a circumferentially extending piston wall, the piston being slidably received within the valve body and having a bore therethrough; a porting assembly for providing a closable fluid passageway between the inlet and the bore, the porting assembly including a first seal adapted to engage the circumferentially extending piston wall of the smaller end of the piston, and biasing means for biasing the piston against the pressure at the outlet towards a first position proximate the outlet from a second position proximate the inlet; wherein in the first position fluid communication is made between the inlet and the outlet via the porting assembly and the bore, and in the second position fluid communication between the inlet and the outlet is prevented by the circumferentially extending piston wall of the smaller end of the piston slidably engaging the first seal of the porting assembly to close the fluid passageway between the inlet and the bore.