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Greg Ryan writes:
>All I've been able to find on this was a pointer in "Diving and
>Subaquatic Medice" (2nd edn) by Edmonds, Lowry and Pennyfeather.
>In the section on skin bends they make the following comment:
>
>"7. Counterdiffusion of gases. There have been occasional reports of skin
>and mucosal swellings due to counterdiffusion of gases. This results in
>bubbles forming at the interface between 2 gases diffusing at different
>rates, but with the total gas pressure at the interface exceeding the
>environmental pressure. This is only likely when the subject's body is
>exposed to a light readily diffusible gas, while he breathes a heavier
>slower diffusing gas. The result is that the light gas moves rapidly
>through the body surface from the environment, while the inhaled gas
>maintains a high tissue pressure which is reduced slowly by diffusion to
>the environment."
>
>This doesn't answer the question of whether it is an issue of concern though.
Well Argon has an atomic mass of 40 and a density of 1.78 gr/cubic centimetre
while Nitrogen (the inhaled gas of importance assuming we are talking air
dives) has an atomic mass of 14 and a density of 1.16 gr/cubic centimetre.
Hence, I would guess that the problems cited above are unlikely to occur.
How much difference does filling a drysuit with Argon make to comfort ? I
gather you can make it warmer also by using more weight and increasing the
inflation of the suit.
As an aside, if you want to be really warm, try Chlorine as the dry suit gas!
It has a thermal conductivity 24 times less than Argon! Too bad about the
toxic and corrosive effects of Chlorine :-)
Another option worth considering is Krypton whose thermal conductivity is half
that of Argon. I suspect that it might be hard to get supplies of Krypton
though.
I am not currently a dry suit diver, but I have been considering it with recent
water temperatures getting down to 11 C (52 F) here in Melbourne and set to
drop further in the next month or two. A new locally manufactured dry suit has
just been released on the market here ("Hot 'n' Dry") for A$790 (approx
US$550). It is a membrane type suit without a hood.
Cheers,
David (about to start a PADI DM course).
______________________________________________________________________________
David Giddy, | Voice: +61 3 253 6388
Telstra Corporation, | Fax: +61 3 253 6144
P.O. Box 249, Clayton, Victoria 3168, AUSTRALIA | Net: d.giddy@tr*.oz*.au*
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