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Julius Loennechen > > [....] The +oxygen > window+ is the non-inert part of a breathing mix which does not contribute > to bubble formation. It is, slightly simplified, the partial pressure of > oxygen at a given depth. This is not my definition of "oxygen window." The oxygen window is the "inherent unsaturation" of the tissues brought about by the consumption of O2 in the metabolic process. Simply stated: you inhale ~21% O2 and exhale only 16% O2. The difference is not completely made up in CO2 produced. Hence you have an "inherent unsaturation" or "oxygen window" into which you can eliminate inert gases, since you have a below normal pressure of gases in your venous blood. > Moreover, with a maximum oxygen window there is more allowance for pressure > reductions without formation of microbubbles. > Examples: Air at 130 feet is approximately 1 atmosphere of oxygen + 4 of > nitrogen. The oxygen window allows an upward excursion of 1 atmosphere (33 > feet). > Nitrox 32 at 130 feet is approximately 1.6 atmospheres of oxygen + 3.4 of > nitrogen. The oxygen window allows an upward excursion of 1.6 atmospheres > (53 feet). > Air versus Nitrox 40 at 100 feet would give oxygen windows of 26 and 53 > feet respectively. I don't believe these are appropriate, given the discussion above. The inherent unsaturation is far less than 26 fsw, let alone 53! > It would be nice to avoid all bubble formation, but that would at least > require a slow sat-style decompression. In practice we can probably do well > with a combination of 1) A large oxygen window 2) A slow ascent 3) Deeper > stops. Nothing but agreement here. Cheers, David Story NAUI AI Z9588, PADI DM 43922, EMT story@be*.wp*.sg*.co* Oxygen is a drug in California.
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