Kevin, I don't know about the rest of you guys, but I sure feel better 
during and after the dive if I keep the PPO2 to 1.1 or even less during 
the working (deep) part of the dive.

You do wind up with a bit more deco but I found that my lungs just don't 
feel as "fried" after the dive. I would much rather extend my bottom time 
using normoxic bottom mixes and then decoing out on nitrox and/or 100%.

This, of course, runs counter to current nitrox training, where divers 
are taught to crank up the PP02 to extend "no stop" dive time. I think 
this is BS and dangerous. If you want to extend bottom time you need to 
do it right with redundant back gas (re: doubles w/isolator) and a deco 
plan using 50%/100%.

   Jim

Sender: Kevin Connell  Date: 9/12/99 10:14 AM

>Scott, the MOD markings are usually as follows:
>
>For deco mixes, 1.6
>For working mixes: 1.4 or less
>
>For example, the standard deco gasses are 35% (120fsw), 50% (70fsw) and 
>Oxygen (20fsw)
>
>A resting decompression Po2 of 1.6 is a well established norm.
>
>And, BTW, is sounds like you plan on ("contingency") breathing your working 
>mix at a 1.6 PPo2.  If you have a real bottom below you, you should mix for 
>1.4 at the bottom.  The benefits of pushing the PPO2s on a working mix are 
>minimal, and the downside is death.  As kirvine says, you can survive the 
>bends, but not a tox.
>
>At 09:29 PM 9/11/1999 -0700, you wrote:
>>With all the discussion regarding tank marking...
>>
>>I've got a question about the practice of using 100% oxygen just before 
>>exiting (something which I have not started to do yet). I dive Nitrox 
>>regularly, and mark my tanks using the calculated mod, not the contingency 
>>depth.
>>
>> From what I've read, I see that WKPP divers mark the sides of their 100% 
>> O2 bottles with the number 20, signifying that one should not be below 
>> twenty feet when breathing the contents of the bottle. It seems that the 
>> 100% O2 bottle marking is an exception to using the MOD, since at 19.8 
>> feet the PP02 is 1.6 ata., which would be the contingency depth. If one 
>> were not using a full face mask when breathing off this tank, I would 
>> guess common sense would tell me that I should wait until I'm at the MOD 
>> before I take a breath.
>>
>>Is this correct, or did I miss something?
>>
>>Scott Gudmundsen
>>Vernal, Utah
>>
>>
>
>
>----------------------------------
>  Kevin Connell <kevin@nw*.co*>
>
>  NW Labor Systems, Inc
>  http://www.nwls.com
>
>  Who is John Galt?
>----------------------------------
>
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>Send mail for the `techdiver' mailing list to `techdiver@aquanaut.com'.
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