Compensated expiratory valves

Claim 1

A COMPENSATED EXPIRATORY VALVE FOR BREATHING APPARATUS OF THE TYPE ADAPTED TO SUPPLY OXYGEN FROM A PRESSURIZED SOURCE TO AN OXYGEN MAS, SAID VALVE INCLUDING: A GENERALLY CYLINDRICALL BODY HAVING A FIXED PARTITION, SAID PARTITION DIVIDING THE INTERIOR OF SAID CYLINDRICAL BODY INTO FIRST AND SECOND CHAMBERS, EACH CHAMBER HAVING AN APERTURE IN THE WALL OF SAID CYLINDRICAL BODY ESTABLISHING COMMUNICATION BETWEEN EACH CHAMBER AND THE EXTERIOR OF SAID BODY, DISC POSITIONED IN SAID FIRST CHAMBER, HAVING MEANS BIASSING SAME TO CLOSE AN APERTURE AT AN INLET END OF SAID FIRST CHAMBER, A FIRST EXPANSIBLE COMPENSATION PRESSURE COMPARTMENT WHICH INCLUDES FLEXIBLE WALLS AND LOCATED IN THE FIRST CHAMBER, SAID FIRST COMPENSATION PRESSURE COMPARTMENT HAVING A PORTION CONTACTING ONE SIDE OF SAID DISC FOR ACTUATING SAME TO AN OPEN POSITION PROVIDING FLOW COMMUNICATION BETWEEN SAID INLET APERTURE AND SAID FIRST CHAMBER WALL APERTURE, A FLUID COMMUNICATION LINE BETWEEN THE INTERIOR OF SAID FIRST COMPENSATION PRESSURE COMPARTMENT AND THE EXTERIOR OF SAID BODY, A CLOSURE HAVING A BLEED HOLE THEREIN CLOSING THE OPEN END OF SAID SECOND CHAMBER, A SECOND EXPANSIBLE COMPENSATION PRESSURE COMPARTMENT WHICH INCLUDES FLEXIBLE WALLS AND LOCATED IN SAID CHAMBER, SAID BLEED HOLE BEING IN FLUID COMMUNICATION WITH SAID SECOND COMPARTMENT, A VENTING PORT IN SAID FIXED PARTITION, SAID VENTING PORT ESTABLISHING FLUID COMMUNICATION BETWEEN THE INTERIOR OF SAID FIRST COMPARTMENT AND SAID SECOND CHAMBER, A VENTING VALVE HAVING MEANS NORMALLY BIASSING SAME TO CLOSE SAID VENTING PORT, SAID VENTING VALVE COMPRISING A STEM CARRIED BY A RIGID PLATE WITH SAID PLATE COMPRISING A STEM SUPPORTED BY A FLEXIBLE WALL PORTION OF SAID SECOND COMPARTMENT, SAID STEM EXTENDING THROUGH SAID GUIDED BY SAID PARTITION, ONE END OF SAID STEM CARRYING A HEAD OVERLYING AND NORMALLY CLOSING SAID VENTING PORT, SAID VENTING VALVE BEING ACTUATED BY THE FLEXIBLE WALL PORTION OF SAID SECOND COMPARTMENT TO AN OPEN POSITION ESTABLISHING COMMUNICATION BETWEEN THE VENTING PORT AND THE SECOND CHAMBER WALL APERTURE, THE EFFECTIVE FLUID PRESSURE AREA OF SAID RIGID PLATE AND OF THE FLEXIBLE WALLS OF SAID SECOND COMPARTMENT WHICH IS EFFECTIVE TO URGE AND VENTING VALVE TO AN OPEN POSITION BEING SUBSTANTIALLY GREATER THAN THE AREA OF SAID HEAD.