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On Tue, 18 Jul 1995, Christopher M. Parrett wrote:
> Recently someone asked about the possible use of Neon and Argon as breathing
> gases for technical diving. I replied that there is some limited usage
> currently occuring with those gases as intermeadiary or transitional deco
gases.
>
while there is some experimental use of these breathing gasses, economics
argues strongly against the use of neon (Ne) while physics argues against
argon (Ar).
-> Ne is about 100 times as expensive as He....all for a very few minutes
"saved." any takers? (only those with sponsors have used significant
quantities of Ne on dives)
-> as far as Ar goes, the diffusivity of Ar (D) is less than N2 and He,
which is good for dives of "short" duration, however the solubilities
(S) in lipid and aqueous tissue are large and this is bad--see below
>
> Question?
> How many of you are seriously interested in the possible usage of these
gases.?
>
Not me. the big boys doing the integrated statistical/bubble modeling
claim they don't even have nitrox diving well modeled--let alone exotic
gasses....i'll take their word on that.
> Abyss now has the ability to generate "hypothetical/experimental" deco
> schedules using Neon and Argon as inert gases.
Chris, i presume that you account for these exotic gasses in abyss by
fractioning the tissue compartments by their respective diffusivities (as
is traditionally done in generating 3-mix/ HeOx tables)--true?
if so, talk to wienke about what the bubble models (vpm, rgbm, vanliew's
stuff, hills, etc & hyldegard+madsen (sic?)) say about potential bubble
growth/amplification. the naive neo-haldane approach of dividing
compartment 1/2 times by D SEEMS to work, though there are no meaningful
statistics to support this claim.
recall that the radial diffusion equation gives the rate of bubble growth
as proportional to D AND S (and the gradient
between bubble internal pressure and tissue tension, etc), see vanliew
et-al for insightful papers. while Ne shouldn't be too different
(better?!) from N2, Ar should not be breathed for any significant amount
of time.
it is well known
that sat divers emersed in He, for eg, can get into big trouble
breathing Ar. while Ar is great as a suit inflation gas (as long as you
breath a lighter & less-soluble inert), you could get into some
counter-diffusion/bubble-amplification trouble doing visa-versa.
any tables generated on a computer using exotic gas mixes and switches
should only be used for decompressing silicon chips....
as the old saying goes: kill your computer....
If there is any real interest
_____________________________________________________________.sig
Eric Maiken email: eapg243@ea*.oa*.uc*.ed*
Dept. of Physics o: 714 824-6621
U of California fax: 714 824 2175
Irvine, CA 92715-4575
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