From: lvogt@digi.lonestar.org (Lee Vogt)
Newsgroups: alt.folklore.science,sci.misc,rec.arts.startrek.tech,rec.scuba
Subject: Re: Human bodies explode in vacuum?
Date: 17 Nov 92 15:34:53 GMT
Organization: DSC Communications Corp, Plano, TX

In article <1992Nov16.145038.23449@geac.com> adb@geac.com (Anthony DeBoer) writes:
>In article <1992Nov13.190025.6323@digi.lonestar.org> lvogt@digi.lonestar.org (Lee Vogt) writes:
>>[Much discussion of the hows & whys of nitrogen narcosis deleted]
>>
>> [another poster wrote]
>>>Nitrogen narcosis usually occurs at depths around 300 feet, or (at 30 ft to
>>>the atm) a pressure change of ten atmospheres.
>> ...
>>Also, at 300 feet, the pressure would be 11 atmospheres, one atm/30 feet
>>(roughly) *plus the one atm of pressure at the surface*.  Always forgot to
>>add that one in myself, too...
>
>Actually, you're both partly right.  The absolute pressure, including the
>one atmosphere at the surface, is just a hair over ten atmospheres, not
>eleven, since it's actually 33 feet of seawater (34 feet of fresh water)
>that exerts a pressure of one atmosphere.  Nine times 33 is 297', plus
>one atmosphere surface, is ten atmospheres.
>
>The 10% error in that approximation throws the calculation by a whole
>atmosphere once you get down to the 10 or 11 atmosphere range.
>

Yup.  Score two points for the visiting team on that one.  I used a previous
poster's approximation without checking the correct value & got bit by the
round-off error....

>>I beg to differ on this point.  I recently completed a class in
>>recreational SCUBA-diving (PADI program) and nitrogen narcosis was mentioned
>>as typically occuring at around 100 feet, if memory serves me properly.  In
>>any case, as the depth limit for recreational SCUBA is 130 ft maximum and 
>>nitrogen narcosis is mentioned as a hazard in the course-book, the statement
>>that 'nitrogen narcosis usually occurs ... around 300 feet' is in error.
>
>100 feet is typical for the onset of nitrogen narcosis, although some
>extremely sensitive individuals have noticed it as early as 60'.  However,
>it gets worse with increased depth, so believe me, you'd be narked at
>300'. :-)
>

Another two points for the visiting team !  I agree completely with this,
and just want to point out that susceptibility to N2 narcosis is HIGHLY
VARIABLE between individuals, and between the same person under different
diving circumstances.

>There are other problems, like oxygen toxicity, carbon dioxide buildup,
>hypothermia, breathing difficulty due to increased gas density, etc.,
>that also rear their ugly heads as you start getting really really deep,
>although your PADI course wouldn't have mentioned these in any great
>detail, if at all, since they're generally not factors yet at the 130'
>they warned you never to exceed.

Actually, all of these problems you mention were discussed in some detail.
If I'm not mistaken, the 130' limit applies to ALL recreational SCUBA diving,
as going deeper than that requires *planned* decompression stops, at which
point it's no longer recreational, but professional, diving.  The main 
difference is that, due to the no-decompression-stop limit, a recreational
SCUBA-diver can surface immediately if an equipment malfunction occurs.  The
diver might still get bent, but would not be in any immediate danger, and it's
much easier to be flown to a hyperbaric chamber from the surface than it is
to grow gills at 100' down  :-}   I would highly
recommend the PADI courses to anybody wanting to learn to SCUBA-dive.   

>Anthony DeBoer       adb@geac.com | uunet!geac!adb | GEM: ANTHONY.DEBOER


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* MY opinions, dammit !!!                      Lee Vogt                    *
*   Keep your grubby paws off !                DSC Communications Corp.    *
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-- 
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* MY opinions, dammit !!!                      Lee Vogt                    *
*   Keep your grubby paws off !                DSC Communications Corp.    *
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Newsgroups: alt.folklore.science