Flow control valve

Claim 1

A VALVE COMPRISING A HOUSING BODY HAVING A PAIR OF PASSAGES AND A VALVE SEAT BETWEEN SAID PASSAGES, SAID HOUSING BODY HAVING AN ADDITIONAL PASSAGE SEPARATE FROM SAID PAIR OF PASSAGES, A VALVE MEMBER MOVABLE BETWEEN A CLOSED POSITION AT SAID VALVE SEAT FOR PREVENTING THE FLOW OF FLUID BETWEEN SAID PAIR OF PASSAGES AND AN OPEN POSITION AWAY FROM SAID VALVE SEAT FOR PERMITTING THE FLOW OF FLUID BETWEEN SAID PAIR OF PASSAGES, SAID VALVE MEMBER HAVING MEANS FOR PRESSURE BALANCING IT BY THE FLUID PRESSURE IN ONE OF SAID PAIR OF PASSAGES WHEN IN ITS CLOSED POSITION, SPRING MEANS BIASING SAID VALVE MEMBER TO ITS CLOSED POSITION, SAID VALVE MEMBER HAVING MEANS, SEPARATE FROM AND INDEPENDENT OF SAID ADDITIONAL PASSAGE, FOR PRESSURE UNBALANCING IT TO MOVE IT TO ITS OPEN POSITION IN RESPONSE TO FLUID PRESSURE AT THE OTHER OF SAID PAIR OF PASSAGES, AND A PLUNGER, SEPARATE FROM AND INDEPENDENT OF SAID LASTMENTIONED MEANS, EXPOSED TO THE PRESSURE IN SAID ADDITIONAL PASSAGE AND ENGAGEABLE WITH SAID VALVE MEMBER TO MOVE THE LATTER TO ITS OPEN POSITION AGAINST THE BIAS OF SAID SPRING MEANS WHEN THE FLUID PRESSURE IN SAID ADDITIONAL PASSAGE RISES TO A PREDETERMINED VALUE.