Oxygen supply system

Claim 1

IN AN OXYGEN SUPPLY SYSTEM FOR USE IN RAREFIED ATMOSPHERES, THE COMBINATION OF A FACEMASK, SAID FACEMASK HAVING AN EXTERNAL AIR SUPPLY LINE WHICH COMMUNICATES WITH THE INTERIOR AREA OF THE MASK AND IS OPENED AT A REMOTE END THEREOF, AN AIR RECIRCULATINGCLOSED LOOP CONNECTED TO THE REMOTE END OF SAID AIR SUPPLY LINE, VALVE MEANS POSITIONED WITHIN SAID CLOSED LOOP FOR PERMITTING ONLY A UNIDIRECTIONAL FLOW OF GAS AROUND SAID LOOP WHEREBY, WHENEVER AN INDIVIDUAL WEARING SAID FACEMAKS EXHALES, HIS EXPIRATIONS ARE DISCHARGED INTO SAID AIR SUPPLY LINE, ENTER SAID AIR RECIRCULATING CLOSED LOOP AND FLOW THEREAROUND IN ONE DIRECTION ONLY, A SOURCE OF COMPRESSED OXYGEN, MEANS INCLUDING A PRESSURE REDUCER AND A DEMAND VALVE CONNECTED BETWEEN SAID SOURCE OF COMPRESSED OXYGEN AND SAID AIR RECIRCULATING CLOSED LOOP FOR FEEDING FRESH OXYGEN INTO SAID LOOP AND INTO SAID AIR SUPPLY LINE IN ACCORDANCE WITH THE RESPIRATORY REQUIREMENTS OF THE INDIVIDUAL WEARING SAID FACEMASK, AIR PURIFYING MEANS POSITIONED WITHIN SAID AIR RECIRCULATING CLOSED LOOP FOR ABSORBING CARBON DIOXIDE, A VALVE CONNECTED TO SAID LOOP, SAID VALVE IN A FIRST POSITION BLOCKING THE CIRCULATION OF AIR WITHIN SAID LOOP AND OPENING A VENTING PATH TO THE ATMOSPHERE TO ONE SIDE OF SAID LOOP, SAID VALVE IN A SECOND POSITION PERMITTING THE CIRCULATION OF AIR THROUGH SAID LOOP AND CLOSING SAID VENTING PATH, AND AUTOMATIC MEANS FOR SWITCHING SAID VALVE BACK AND FORTH BETWEEN SAID FORTH AND SECOND POSITIONS IN ACCORDANCE WITHA PRE-ESTABLISHED SCHEDULE SUCH THAT DURING CORRESPONDING FIRST INTERVALS OF TIME SAID INDIVIDUAL CAN INHALE PUR OXYGEN ON DEMAND FROM SAID OXYGEN SUPPLY SOURCE AND DISCHARGE HIS EXHALATIONS INTO THE ATMOSPHERE AND DURING SECOND INTERVALS OF TIME REHBREATHE HIS EXHALATIONS AFTER THE CARBON DIOXIDE CONTENT THEREOF HAS BEEN REDUCED BY THE ACTIOON OF SAID AIR PURIFYING MEANS, SAID FIRST INTERVALS OF TIME AND SAID SECOND INTERVALS OF TIME BOTH BEING LONG COMPARED TO THE TIME BETWEEN SUCCESSIVE INSPIRATIONS OR EXPIRATIONS OF SAID INDIVIDUAL.