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From: "Isaac Callicrate" <icallicrate@ho*.co*>
To: mjblackmd@ya*.co*, techdiver@aquanaut.com
Subject: Re: Oxygen Clock
Date: Sat, 08 Dec 2001 02:50:59 -0500
Im not sure why everyone is harping on who this guy is or what he has posted 
in the past instead of answering his questions.
Am I missing something in the charter that says you have to rate an answer 
or that previous posts disqualify you from getting one?
Ill give it a shot even though there are probably more informed qualified 
people on this list that should be.
I see WKPP as crossing the grey area between recreational and working diving 
(watch out for OSHA, ADC, and USCG). They are performing dives where more 
compartments are saturated than most other recreational profiles. They have 
been diving similar profiles over and over so have built up an amount of 
historical data combined with some doppler research that they have used to 
make assumptions about their profiles.
I dont think anyone can say right or wrong yet. If their people arent having 
DCS manifestations or O2 toxicity issues than I would definately say that by 
being the guinea pig and letting the rest reap the rewards of the data they 
are rising above.
Please do the math on a Navy standard TT 6A with 50/50 @ 165' and 100% @ 
60'. Do it on a Navy single exposure of 100% at 25' for 240 minutes.  Why 
havent you e-mailed them? Please CC me when you do. I think it is 
publicaffairs@ne*.na*.na*.mi*
WKPP isnt the only one that challenges theoretical formulas and assumptions 
with historical data. Commercial, military, hyperbaric facilities all have 
modified the standard thinking on the CNS clock.
My personal feelings, I wouldnt recommend pushing the clock on a working 
dive when not required. For recreational dives, there is no need to push it 
when you are having fun. If you use a habitat or a chamber or maybe at rest 
during deco with surface support, the risk is minimized.
I dont think that taking breaks off O2 is going to significantly effect your 
susceptibility to a CNS hit. That is speculation and if anyone has data to 
prove otherwise I would love to examine and try to push it through to some 
people.
About cumulative pulmonary issues, I would absolutely take breaks every 
20-25 min for extended exposures. With increases as neccessary.
The only big no-no I see is deco on 100% @ >1.6 w/o a ffm, hat, or in a 
controlled environment. I dont think WKPP is doing that. I think they use a 
habitat for extended oxygen. Their protocol incorperates breaks between O2 
periods.
What data is NOAA basing their CNS clocking off of? Historical or Empirical? 
Do you side with someones calculator or slide rule?
For technical diving I think everyone should be taught to do a personal risk 
analysis for Accelerated Deco vs O2 tox.
Where do you draw the line? We can use good models for DCS and pretty much 
say if you do this profile you will get bent. O2 clock is more like 
speeding. Doing 25 is safer than 65 or 100 or 20,000. We dont know where you 
cross the line to get in a guaranteed O2 "accident". We need more data.
All said, everyone enjoy your hit, have the ME e-mail me.

>From: "Michael J. Black" <mjblackmd@ya*.co*>
>To: Aquanaut Mail <techdiver@aquanaut.com>
>Subject: Oxygen Clock
>Date: Wed, 5 Dec 2001 16:26:40 -0800 (PST)


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