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Erik Maiken asked:
>Some questions re your freezing posts:
>What 1st stage(s) were used with the EXO mask?

The EXOs were used with various first stages.  I know some dives were made
with the Poseidon Cyclon first stage.  I believe that most dives were made
using a Sherwood first stage however. 

>What do you think about the "exothermic" 2nd stage with regards to 
>freezing?

I don't know... I understand the principle.  The exhaled air is directed
around the demand valve.  This allows it time to give up some of its heat.  In
*very* cold water this also allows more time for the condensation to freeze. 
I like the mask but, as with all full face masks, I don't think they are as
safe to use in freezing conditions as a conventional second stage.  I want to
be able to switch to my redundant breathing system in a hurry and without
losing my vision.

>In regards to the Poseidon Odin/Thor data, it seems that the unbalanced 1st 
>stage (as found on the cyclon 300 & Thor/Oceanair) is less susceptible to 
>freezing (assuming identical 2nd stages).  
>Is this a "real" effect (your data sets seem large enough to tell). If it 
>is "real," why? My guess would be that the reduced flow of the unbalanced 
>reg (~1000L/min) compared to The balanced reg (~1800 L/min) would lead to 
>less gas cooling upon expansion from the tank to intermediate pressure. 

Yeah, that would be my guess also.  High flow rates definitely tend to lead to
freeflows.  Deep or high exertion dive have a higher likelihood of a freeflow.
 Once a slight freeflow starts it tends to grow rapidly (due to the increased
gas flow).

Cheers-  Rob

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