Low pressure pilot valve

Claim 1

A PILOT VALVE FOR USE WITH A FLUID PRESSURE DEVICE HAVING A PASSAGEWAY, A VALVE SEAT IN SAID PASSAGEWAY AND A BALL CHECK VALVE SEATABLE ON SAID VALVE SEAT BY FLUID PRESSURE UPSTREAM OF SAID VALVE SEAT, SAID PILOT VALVE COMPRISING: A HOUSING HAVING A BORE THEREIN CLOSED AT ONE END AND OPEN AT THE OTHER END THEREOF, SAID HOUSING BEING ADAPTED TO BE CONNECTED TO SAID FLUID PRESSURE DEVICE SO THAT THE OPEN END OF SAID BORE IS IN FLUID COMMUNICATION WITH SAID PASSAGEWAY DOWNSTREAM OF SAID VALVE SEAT, A PLUNGER DISPOSED IN SAID BORE FOR AXIAL MOVEMENT BETWEEN FIRST AND SECOND POSITIONS THEREIN, SAID PLUNGER BEING ADAPTED TO ENGAGE SAID BALL VALVE TO UNSEAT SAID BALL CHECK VALVE WHEN SAID PLUNGER IS IN ITS FIRST POSITION AND TO ALLOW SAID BALL CHECK VALVE TO BE SEATED WHEN SAID PLUNGER IS IN ITS SECOND POSITION, FIRST AND SECOND SEAL MEANS SEALING BETWEEN SAID PLUNGER AND BORE AT SPACED APART POINTS ADJACENT SAID OPEN AND CLOSED ENDS OF SAID BORE RESPECTIVELY, THE AREA SEALED BY SAID FIRST SEAL MEANS BEING LESS THAN THE AREA SEALED BY SAID SECOND SEAL MEANS, PASSAGE MEANS FLUIDLY COMMUNICATING THE OPEN AND CLOSED ENDS OF SAID BORE, SPRING MEANS FOR RESILIENTLY BIASING SAID PLUNGER TO ITS SECOND POSITION, AND MEANS FOR VENTING SAID OPEN END OF SAID BORE THROUGH SAID HOUSING TO ATMOSPHERE WHEN SAID PLUNGER IS IN ITS SECOND POSITION.