Fire extinguisher discharge valve

Claim 1

A FIRE EXTINGUISHER DISCHARGE VALVE COMPRISING A HOUSING HAVING AN INLET AND AN OUTLET AND A FLUID PASSAGE THEREBETWEEN, A MAIN VALVE SEAT DEFINING INLET AND OUTLET PORTIONS OF THE FLUID PASSAGE, A VALVE MEMBER ADAPTED TO ENGAGE THE VALVE SEAT FROM THE INLET SIDE, A DOUBLE FACED PISTON MEMBER INTEGRAL WITH THE VALVE MEMBER, THE VALVE MEMBER FORMING PART OF THE FRONT OF THE PISTON MEMBER, CYLINDER MEANS IN THE HOUSING ON THE INLET SIDE OF SAID SEAT, SAID PISTON SEALINGLY AND SLIDABLY MOUNTED IN THE CYLINDER MEANS IN THE HOUSING ON THE INLET SIDE OF SAID AWAY FROM ITS SEAT, THE PISTON HAVING FRONT AND REAR FACES, THE AREAS OF EACH FACE OF THE PISTON GREATER THAN THE AREA OF THE VALVE SEAT AND THE REAR FACE HAVING A GREATER AREA THAN THE FRONT FACE, SAID PISTON HAVING AN AXIAL RECESS IN ITS REAR FACE, PRESSURE EQUALIZING FLUID PASSAGE MEANS LEADING FROM THE FRONT FACE OF THE PISTON TO THE REAR FACE THEREOF THROUGH SAID PISTON AND RECESS SO THAT THE PISTON IS NORMALLY URGED INTO VALVE CLOSING POSITION BY THE PRESSURE OF FLUID IN ITS INLET PASSAGE, VENT MEANS, IN THE END OF THE CYLINDER FOR VENTING PRESSURE FROM THE CYLINDER BEHIND THE PISTON, A VALVE SEAT ABOUT THE VENT MEANS, A NORMALLY CLOSED VENT VALVE MEMBER WITHIN THE CYLINDER ENGAGING THE VALVE SEAT AND ADAPTED TO BE OPENED TO RELEASE PRESSURE FROM THE REAR FACE OF THE PISTON SO THAT THE MAIN VALVE MEMBER IS OPENED RESPONSIVE TO INLET PRESSURE ON THE FRONT FACE OF THE PISTON, FLUID PASSAGE LIMITING MEANS HAVING A SMALLER PASSAGE THAN SAID VENT MEANS IN SAID FLUID PASSAGE MEANS LEADING FROM THE FRONT TO THE REAR FACES OF THE PISTON THROUGH THE VENT VALVE AT A FASTER RATE FACE OF THE PISTON THROUGH THE VENT VALVE AT A FASTER RATE THAN IT ENTERS FROM THE INLET, AN EXTENSION FOR THE VENT VALVE MEMBER EXTENDING AXIALLY INWARDLY OF THE CYLINDER AND HAVING A PORTION THEREOF SLIDABLY ENGAGED IN THE PISTON RECESS, SAID FLUID PASSAGE MEANS INCLUDING A FLUID PASSAGEWAY THROUGH SAID EXTENSION, AND MEANS RENDERING SAID LAST MENTIONED MEANS INEFFECTIVE WHEN EITHER OF THE VALVE MEMBERS ARE UNSEATED.