Abstract: A breathing gas supply system for an aircraft includes a plurality of oxygen concentrating apparatus, each of which in use, is operable to supply oxygen enriched gas to a breathing gas supply. Each oxygen concentrating apparatus includes at least two active molecular sieve beds which are operable so that while one sieve bed is adsorbing non-oxygen gas from a pressurized gas supply, the or another bed is being purged of non-oxygen gas by subjecting the bed to lower pressure. 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 supply and permits a restricted flow of oxygen enriched gas from the breathing gas supply to the oxygen concentrating apparatus. Oxygen enriched gas produced by the adsorbing sieve bed flows direct to the bed being purged.

Abstract: A breathing gas supply system for an aircraft includes a plurality of oxygen concentrating apparatus, each of which in use, is operable to supply oxygen enriched gas to a breathing gas supply. Each oxygen concentrating apparatus includes at least two active molecular sieve beds which are operable so that whilst one sieve bed is adsorbing non-oxygen gas from a pressurized gas supply, the or another bed is being purged of non-oxygen gas by subjecting the bed to lower pressure. 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 supply and permits a restricted flow of oxygen enriched gas from the breathing gas supply to the oxygen concentrating apparatus. Oxygen enriched gas produced by the adsorbing sieve bed flows direct to the bed being purged.

Abstract: A method of controlling a gas adsorption apparatus including a sieve bed containing molecular sieve bed material, the bed being cyclically operable in a charge mode to adsorb non-product gas from an air supply thereby to increase the concentration of a product gas in a product gas supply which passes to a product gas line and in a vent mode to desorb the adsorbed non-product gas which passes to a non-product gas line, and there being a passage to permit a restricted amount only of the product gas supply to pass from the product gas supply line to the bed when operating in vent mode, and wherein the method includes operating a variable flow device to permit an increased amount of the product gas supply to pass to the bed when operating in vent mode, under predetermined conditions.

Abstract: A method of controlling a gas adsorption apparatus including a sieve bed containing molecular sieve bed material, the bed being cyclically operable in a charge mode to adsorb non-product gas from an air supply thereby to increase the concentration of a product gas in a product gas supply which passes to a product gas line and in a vent mode to desorb the adsorbed non-product gas which passes to a non-product gas line, and there being a passage to permit a restricted amount only of the product gas supply to pass from the product gas supply line to the bed when operating in vent mode, and wherein the method includes operating a variable flow device to permit an increased amount of the product gas supply to pass to the bed when operating in vent mode, under predetermined conditions.