Patent ID: 8424525

Claim:
In a breathing gas supply system for an aircraft including a plurality of oxygen concentrating apparatus connected in parallel to supply oxygen enriched gas to a single breathing gas system supply line, each oxygen concentrating apparatus including at least two molecular sieve beds which are operable so that while at least one sieve bed is adsorbing non-oxygen gas from a pressurized gas supply at least one other sieve bed is purged of non-oxygen gas by subjecting the bed to a pressure lower than the pressurized gas supply and a flow of oxygen enriched purge gas, the improvement wherein each oxygen concentrating apparatus includes an oxygen enriched gas flow control device which permits the flow of oxygen enriched gas produced by the oxygen concentrating apparatus to the breathing gas system supply line, each oxygen concentrating apparatus includes a flow path for providing oxygen enriched gas produced by an adsorbing sieve bed of the oxygen concentrating apparatus direct to at least one bed in such oxygen concentrating apparatus for providing a restricted flow of purge gas to such bed, and means for providing an alternate restricted flow of oxygen enriched purge gas from the breathing gas system supply line to an oxygen concentrating apparatus when a sufficient flow of purge gas is not available from an adsorbing sieve bed in such apparatus for purging a sieve bed within such apparatus.