Mt Whitney Zone Forums General Discussion High altitude survival airplane quiz

nice to see Inyokern connection

In a pressure-demand system, oxygen in the mask is above ambient pressure, permitting breathing above 34000 feet. Because the pressure inside the mask is greater than the pressure around the user's torso, inhalation is easy, but exhalation requires more effort. Aviators are trained in pressure-demand breathing in altitude chambers. Because they seal tightly, pressure-demand-type oxygen masks are also used in hyperbaric oxygen chambers and for oxygen breathing research projects with standard oxygen regulators.

Interesting physics. We think about the act ( and need) of inhaling the oxygen under pressure, but exhaling is a problem with using only a pressure demand system. Eventually, one must use a full suit so the the whole body is pressurized (like in the picture in that link of the late- Steve Fossett and Mr. E. in New Zealand). This is getting way out of my league. Thanks, Harvey