In Archive-Message-Number 7639, Gerry Williams [email removed]
writes:
> There are easy ways to neutralize the CO2, however. Divers
> that use recycled air do this (supplementing with additional
> O2). There are also ways to convert it back to O2 (I think
> submarines do this now).
Old style rebreathers used CaCO3 to absorb CO2. Modern rebreathers
crack the CO2 electrically and recycle the O2. This is the same
method used aboard nuclear subs.
> The real hazard is that pure O2 is deadly at ANY kind of
> pressure above 1 atmosphere. Pure O2 will allow you to
> breathe at a LOWER pressure, however.
Not quite accurate. O2 toxicity begins at 2 ATMs of 100% O2.
Anything less is not normally dangerous. This is the reason
that std. compressed air diving is physiologically limited to
a max. depth of 289 FSW (ft. of Sea Water). That equals 9
ATMs (atmospheres) of sea water, plus 1 for the surface, for
a total of 10 ATMs. The rounded value of O2 as comprising 20%
of normal air, gives it a partial pressure of 2 ATMs at 288
FSW. Any deeper diving requires custom mixed gases.
Mark F. Cook - PADI Rescue Diver #88348821
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mark f. cook * mark cook consulting * shoestring graphics & printing
2055 sw whiteside dr. * corvallis, or, 97333-1406 * [email removed]
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