Date: 08 Jan 2000 13:39:05 From: "Hugo 'NOx' Tyson" <firstname.lastname@example.org> Organization: Cygnus Solutions, Cambridge, UK References: 1 2 Followups: 1 2
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email@example.com (GLPILOTSRV) writes: > I would not doubt the statement. Drop down oxygen systems do not supply > oxygen under pressure. Above approximately 25,000 feet, oxygen needs to > be supplied under pressure, otherwise the hemoglobin will not absorb the > oxygen present. I think you misunderstand partial pressure: the body is quite happy with 100% O2 @ 0.21 Bar or 50% O2 @ 0.42 Bar or 21% O2 at 1 Bar - it really makes no difference. I thought the point of passenger O2 systems is they let you breath a higher %age of O2 at ambient pressure, thus giving enough partial pressure to stay alive (even if not conscious). According to the www ;-) "To convert from pressure to height, just remember two rules: 1.Sea level pressure is about 1000 mb; 2.For every 5.5 km increase in height, the air pressure decreases by a factor of two." So at a typical cruise of 11km (36,300ft) you get 0.250 Bar ambient, so you need about 80 %O2 or better to stay conscious. Your statement would be OK if it said "above 50,000 feet" where even 100% O2 at ambient isn't enough. - Huge -- The 20th Century brought unprecedented increases in worldwide numeracy and literacy and incredible advances in technology, science and mathematics. It was also the only century in the past or in any reasonable predictable future apparently to contain only 99 years.