>Yes, there are some indirect (and mostly trivial) affects of depth.  One 
>of them is that the total gas mixture is denser at depth.  This would 
>have a two-fold effect; 1) it would increase your work of breathing, and 
>therefore increase the CO2 production at a given exertion level; and 2) 
>it would cause more efficient cooling of the absorbent (and we all know 
>that absorbents don't work as well when cold).
>
>However, I sa 1) these are relatively trivial for the discussion at hand, 
>and 2) do not apply if a diver switches from nitrox in shallow water to 
>heliox in deep water.
Rich,
I'm not sure that this would be trivial; remember the navy units had/have 
metal scrubbers so that temp is significant due to poor insulation of the 
absorbent material.  Second, I grant you that you dive in warm water and 
the greatest flucation I've seen over on Ohau is 78 on the surface to 75 
at depth or so.  Here, in S. Cal. on a recent dive to 220fsw next to the 
Redondo trench (on the wreck of the Sacramento, an old side wheel 
steamer) we went from 66 at the surface to 49 at depth. Not only a larger 
change in overall temp, but colder temps period.  That alone could 
explain the Navy's reccomdendations etc.

PS sorry to butt in here, but I've been following the discussion and as a 
soon to be owner of one of the units you got me thinking with the last 
remark especially since my unit will have a smaller scrubber etc.

Harold H. Gartner III
E-Mail:
hgartner@ra*.or*
CompuServe 71470,1423

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