Pressurizing and drain valve

Claim 1

A PRESSURIZING AND DRAIN VALVE FOR USE IN A FLUID SUPPLY SYSTEM COMPRISING A PRESSURIZED FLUID SOURCE FOR SUPPLYING FLUID TO A MANIFOLD OR THE LIKE AND A REFERENCE PRESSURE SOURCE, SAID VALVE COMPRISING: A HOUSING HAVING A BORE FORMED IN AN INTEGRAL PORTION THEREOF, A PISTON SLIDABLE IN SAID BORE AND DEFINING, IN PART, FIRST AND SECOND CHAMBERS AT OPPOSITE ENDS THEREOF, A VALVE GUIDE MOUNTED ON SAID HOUSING AND SLIDABLY RECEIVING THE END OF SAID PISTON DEFINING SAID SECOND CHAMBER, A PORT FOR CONNECTING SAID SECOND CHAMBER TO SAID FLUID PRESSURE SOURCE AND ANOTHER PORT FOR CONNECTING SAID FIRST CHAMBER TO SAID REFERENCE PRESSURE SOURCE, WHEREBY THE PISTON IS URGED TOWARD A FIRST POSITION WHEN THE REFERENCE PRESSURE FORCE EXCEEDS THE PRESSURIZED FLUID SOURCE ON SAID PISTON, AN ANNULAR CHAMBER, WITHIN SAID HOUSING SURROUNDING SAID PISTON AND DEFINED IN PART BY THE SIDE OF SAID GUIDE TOWARDS THE OTHER END OF SAID PISTON, A PRESSURIZED FLUID OUTLET OPENING INTO SAID ANNULAR CHAMBER AND OVERLYING A PORTION OF THE HOUSING IN WHICH THE BORE IS FORMED, AT LEAST ONE CONNECTING PASSAGEWAY, WITHIN THE OUTLINE OF SAID OUTLET, CONNECTING SAID OUTLET WITH SAID BORE, A DRAIN OUTLET OPENING INTO SAID BORE AT A POINT OFFSET FROM SAID CONNECTING PASSAGEWAY TOWARDS SAID OTHER END OF SAID PISTON, AN ANNULAR GROOVE FORMED IN SAID PISTON AND REGISTERING BOTH WITH SAID CONNECTING PASSAGEWAY AND SAID DRAIN OUTLET IN SAID FIRST PISTON POSITION, SAID PISTON HAVING A RECESS OPENING INTO SAID SECOND CHAMBER AND AN OPENING THERETHROUGH, SAID OPENING BEING BLOCKED BY SAID GUIDE IN SAID FIRST PISTON POSITION AND CONNECTING SAID PRESSURIZED FLUID SOURCE WITH THE OUTLET THEREFOR WHEN THE PISTON IS DISPLACED TOWARDS ITS SECOND POSITION A DISTANCE SUFFICIENT TO REMOVE THE PISTON GROOVE FROM REGISTER WITH THE CONNECTING PASSAGEWAY.