Breathing systems in aerospace

Closed circuit breathing systems are employed in aerospace activities where great economy in the use of oxygen is required as on the surface of the moon away from the spacecraft. The high efficiency, reliability and compactness of modern molecular sieve oxygen concentrators operating on bleed air from the aircraft engines have made this technology the method of choice for the supply of breathing gas to the pilot especially in high performance combat aircraft. This technology is slowly being applied to larger passenger carrying aircraft