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Reply to: RE>>FFESSM: Nitrox for 're Carl, >>I would like to see the emphasis for using NTX changed from *you >>can dive longer* to *you can dive safer*. In the area I am in(southern >Yes, this is definitely the way it should be used by "recreational" >divers, however... >>California), the emphasis on selling NTX training courses is "dive >>longer". Most of the people that get NTX trained don*t realize that >>diving longer on NTX (just as close to the edge as they dive on air) >>is NOT safer. It is these divers that already lack the discipline to >>adhere to depth and time limits and they use NTX to go past the air >>NDL (for fun, lack of discipline, etc) not realizing that they are >>probably in MORE danger due to OXTOX, Low air (NTX) situations >>(want >>to use all of the NTX that they paid for), and DCI from longer dives >>(lack of discipline, planning). >I've only had a very small amount of sleep (we're moving tomorrow), >so please correct me if I'm wrong, but... >The "standard" depth limits for nitrox are: >32% O2 - 130' PPO2 @ Max Depth = ~ 1.6 >36% O2 - 100' PPO2 @ Max Depth = 1.45 Right >For any reasonable dive, you will NOT hit the O2 Tox limits of Nitrox >II if you are diving at <100', the real concern is diving too deep >with Nitrox and to that I say - *personal responsibility*. The >standard limits for O2 Tox are 45 min at 1.6 atm, so if you back off >of the max depth limit of Nitrox I a little (to a PPO2 of 1.5 atm) >you'd be well within the save ranges for O2 Tox limits and since "rec" >nitrox is done without planned deco, the dive time limits should be >hit long before O2 Tox is reached. These are PULMONARY O2 toxicity limits. I was referring to CNS OXTOX limits, which can be immediate. I do realize that you have not had much sleep so this is not a flame. My emphasis is that I know alot of recreational divers that lack the discipline to adhere to there preset depth and time limits (if they had a plan at all) on air. This lack of discipline on air just carries over to NTX, causing a more dangerous situation. >>Recreational NTX is fine. I would just like to see the emphasis >>changed >>(I do not expect that to happen anytime soon). >Well, when done properly, bottom times can be extended safely, you >just really need to look at the margin you're leaving yourself on the >deco limit and the percentage tissue loading. If you're diving up to >90% tissue loading now and you switch to nitrox, extend your dive >times, but limit yourself to 80% tissue loading, I would maintain that >you have safely increased your bottom time (I realize that you said >"diving within the same margin")... Most recreational divers I know also would not even stop to think about tissue loading or margin. Just hop in and dive. Even those that are NTX certified have forgotton (through I assume lack of use) how to figure what they need (or feel they need) to be safe. >-Carl- P.S. How did the move go? Steve Hogan Steve_Hogan@qm*.sp*.tr*.co*
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