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"Michael J. Black" wrote: > On 5/27/00, George Irvine (Trey) wrote: > > > I am a psychopath, not a sociopath, and my track record speaks to the > > rest. Black is a pussy who did not like being corrected fro extreme > > ignornat stupidity. > > No George, even I don't think you are psychotic, but that could change. > As for my "extreme ignornat stupidity" were you referring to the pony > bottle with pO2 1.9 debate? Its nice to see that we're back to the beginning of this whole flame war. > Thought so, and just FYI here is what TDI > says in one of their coursebooks (authored I believe by Jan Neal, who > IS a BEST diver, i.e. absent from this list): > > "A small volume scuba cylinder of EAN39 carried with a diver for a > decompression gas can also be a redundant gas supply. EAN 39 is inefficient as a decompression gas. EAN 50 or 100%O2 in a separate deco bottle would be much more efficient. Prove it to yourself by running a profile on any dive planning software and note the difference in total dive time. > In the event > that the primary gas supply is exhausted, the diver can switch to > EAN39 and make a normal ascent. If this emergency occurred at 130 fsw, > the pO2 for EAN39 would be 1.92 ATA. Although the recommended maximum > oxygen depth limit for EAN39 is 102 fsw (pO2 1.6 ATA) the exposure > time for an ascent from 130 fsw to 100 fsw would only be 30 seconds. Lets assume for the moment that you're not penetrating a wreck with your PO2 1.9 pony. What about the risk from entanglement at depth? If this is the case your trip to 100 fsw may take considerably longer than 30 seconds. So why try to justify a mix that can only increase your risk while diving rather than going with EAN 32 in your pony which has an MOD of 130 fsw? Please justify your decision in some logical manner. > > In this situation the pony cylinder becomes a "bail-out bottle." The > risk for CNS O2 toxicity is minimal, especially compared to the > alternative of no bail-out. In this situation, EAN39 provides > operational safety as a bail-out gas shallower than 130 fsw without > the need for an oxygen clean regulator that is required for higher > mixes. Thus, when carrying a pony cylinder of EAN39, operational > and physiological safety is increased." > MJB :-))) > > Although I find it interesting/disturbing that this advice exists in > printed material from a training agency I still don't see the logic in it > and I would be interested in how you can justify this setup. Eric Nelson -- Send mail for the `techdiver' mailing list to `techdiver@aquanaut.com'. Send subscribe/unsubscribe requests to `techdiver-request@aquanaut.com'.
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