This report describes the methods used in the evaluation of a new continuous-flow, phase-dilution passenger oxygen mask for compliance to FAA technical Standard Order (TSO)-C64 requirements. Data presented include end expiratory partial pressures for oxygen, carbon dioxide, and nitrogen at selected altitudes and oxygen flow rates. Data indicate that the test mask does meet the requirements for TSO-C64 certification.

A number of techniques for determining the protective efficiency of passenger and crew masks was developed, utilized and compared. In the case of newly developed passenger masks, subjects were exposed to a chamber flight profile designed around the National Aerospace Standard 1179. The two alternative methods of determining mask performance suggested in this document and based on gas analysis and blood oxygen saturation were used simultaneously in this study for comparison. Evaluation of newly developed crew oxygen masks was divided into three phases. The first phase consisted of exposing the subjects to a stepwise flight profile with a maximum altitude of 43,000 feet while wearing the mask. The second phase consisted of rapidly decompressing the subjects from 8,000 to 40,000 feet in 45-50 seconds while wearing the mask. The third phase consisted of rapidly decompressing these subjects from 8,000 to 40,000 feet with delayed donning of the mask during the decompression. Instrumentation of subjects provided for simultaneous determination of seven physiological parameters during decompression which are compared and discussed. Results of these experiments indicate that, insofar as design standards are concerned, the present criteria based on inspired oxygen partial pressure are satisfactory, but should be supplemented by determination of blood oxygen saturation during chamber evaluations. (Author).

A redesigned continuous flow passenger oxygen mask was tested for its ability to deliver an adequate supply of oxygen at an altitude of 40,000 feet above sea level. Four male subjects participated in the study. Blood oxygen saturation (SaO2) baseline levels for hypoxic exposure were established for each subject. Immediately prior to high altitude exposure, subjects prebreathed 100% oxygen for two hours through a pressure demand type mask. The hypobaric chamber was then decompressed to a simulated altitude of 35,000 feet. Subjects switched to the passenger oxygen mask. The initial oxygen flow rate to the passenger mask came from manufacturer production performance test data. Once heart and respiratory rates and SaO2 level stabilized, chamber altitude was increased to 40,000 feet. Descent to ground level was performed in steps of 5,000 feet with SaO2 levels being established for each altitude and recommended oxygen flow. Subjects remained at each test altitude for a minimum of three minutes or until SaO2 levels stabilized. At no point during the testing did SaO2 levels approach baseline levels for hypoxic exposure. This mask design would appear to offer protection from hypoxia resulting from altitude exposure up to 40,000 feet.