Patent ID: 8656941

Claim:
A flow control valve, comprising: a first seat spaced from a second seat, the first and second seats having openings therethrough; a pilot poppet disposed between the first and second seats and movable along an axis, the pilot poppet having first and second sealing surfaces which alternatively seal against the respective first and second seats; a primary poppet having a sealing surface to seal against a primary seat, the primary poppet sealing against the primary seat when the pilot poppet is sealed against the first seat and the primary poppet being unseated when the pilot poppet is sealed against the second seat; a pressure passage between the first and second seats in communication with an inlet of the valve, the pressure passage being in communication with the first and second seat openings when the pilot poppet is sealed against the first seat and blocked from the first and second seat openings when the pilot poppet is sealed against the second seat; and a vent passage between the first and second seats in communication with a low pressure area, the vent passage being blocked from the first and second seat openings when the pilot poppet is sealed against the first seat and in communication with the first and second seat openings when the pilot poppet is sealed against the second seat.