This standard defines the minimum requirement for the design, construction and performance of continuous flow oxygen masks for crew and passengers of general aviation civil aircraft.

This standard defines the minimum requirement for the design, construction and performance of continuous flow oxygen masks for crew and passengers of general aviation civil aircraft.

This report is intended to acquaint personnel involved in the design, inspection, and maintenance of civil transport oxygen systems with the human respiratory requirements and oxygen system design considerations necessary to effect an interface and provide acceptable high-altitude life support. Simplified explanations and language that should be understandable by lay and semiprofessional engineering personnel are used, with references to sources of more detailed information. The oxygen system designer is directed to applicable Federal Aviation Regulations pertaining to oxygen systems and, where regulatory guidance does not exist, directs the reader to applicable oxygen equipment industry practices, standards, and information reports. (Author).

The report describes evaluation of two prototype phase dilution rebreathing masks as compared to an open port rebreathing mask design. Human subjects wearing the prototype masks and engaged in three minute periods of rest and exercise were exposed to altitudes of 14,000, 18,000, 25,000, 30,000 and 34,000 feet in an altitude chamber. Each subject was instrumented to obtain a variety of physiological parameters including end expiratory gas composition, blood oxygen saturation (ear oximetry), ECG, and respiratory rate (impedance pneumograph). Oxygen flow and system pressure as provided by an automatic constant-flow regulator were also determined. The automatic constant-flow regulator when used in conjunction with either of the prototype phase dilution rebreather test masks and proper orifices maintained the subjects' indicated blood oxygen saturations equal to or in excess of their ground level (1,273 feet) baselines. With the same oxygen flow rates the prototype porous and dilution valve masks provided higher tracheal oxygen partial pressures than the open port masks at all altitudes tested during rest and exercise. The prototype phase dilution rebreather masks appear to be more efficient since at the same flow rates a greater amount of oxygen was derived from the supply and less oxygen lost to the ambient environment as compared to the open port type mask. (Author).