Comparison of Protective Breathing Equipment Performance at Ground Level and 8,000 Feet Altitude Using Parameters Prescribed by Portions of FAA Action Notice A-8150.2

Two types of crewmember protective breathing equipment PBE were performance tested for compliance with Action Notice A-8150.2 at ground level - 1,300 feet and 8,000 feet altitude. PBE 1 was a hood with oral-nasal mask, which used potassium superoxide to remove carbon dioxide and produce its oxygen supply. PBE 2 was a hood only, which contained lithium hydroxide to absorb carbon dioxide and compressed oxygen cylinders to supply breathable air. The parameters tested were PBE oxygen and carbon dioxide levels, temperature, and breathing resistance-pressure. Five units of each PBE type were subjected to testing for within-PBE comparisons each type of unit was worn by the same human subjects at both altitudes. Relatively little difference in PBE performance was obtained at the different altitudes for both types of PBE. Oxygen partial pressures were somewhat reduced at the higher altitude for both types of PBE, carbon dioxide partial pressure was slightly greater at ground level for PBE 2, internal temperature was higher for PBE performed adequately for the intended purpose at either altitude , but further testing would be necessary to certify PBE to meet additional requirements, such as use at altitudes above 8,000 feet.