BDSC
Contributor
Thanks Snake for starting this thread. It's one of the better threads I have seen on SB and I appreciate all who have responded. It has been quite educational.
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Danvolker is right on the money in post 5.
The Navy and commerical divers were given O2 tolerance tests which gave an idea of general tolerance to higher P02. It was risky because what they were really getting was their tolerance on that day. When these guys left the service/job some continued to dive and knew their "limits" others learned from those guys and found their own limits such as Danvolker posted " and the rest never felt good below 200." I'm going back further than the 90's here, my perspective startes back in the 70's, before Nitrox and trimix was common to sport divers.
Im confused. I have never been around a sat with PPO2s above 0.8 ATA in the water, usually more like 0.3. Granted, its been a while since I was offshore but why bother unless you are running crazy deep excursions (diving well below the saturation holding depth in the deck chamber)? Deep bounce dives with a small bell system is another matter but I didnt think much of that was done anymore.
Barfing in a hat is a good reason to pull a diver even if they are in 30' on air. Burping often gets the mask yanked, at least for 10-30 minutes. All the barfing in hats I have witnessed had more to do with excessive Tabasco on breakfast or the previous nights celebration than gas mixes.
---------- Post added May 16th, 2012 at 10:12 AM ----------
Are any military or commercial diving schools still running Oxygen Toxicity tests? I heard the US Navy stopped years ago concluding they were not very predictive of individual sensitivity. It is ironic that they would test you before going into sat since Sur-D-O2 usually exposes divers to far higher risks.
Personally I am glad I did the test for the self-confidence factor but it was only my second chamber ride so it was still fun at that point.
Ha ha ha ... not Ox Tox ... maybe BH will illuminate us with further details of what his toxicity was due to ... you can probably guess.
The time to convulsion in turn is modified by the partial pressure of carbon dioxide, a vasodilator. When a diver is in the water and breathing elevated oxygen pressures, the activity of the diver is contributing to the production of CO2. An accumulation of CO2 has been found to influence the time to convulsion.
The Britannic dives as I recall were with triples and quads 72s/80s filled with different blends. Once below 10th most blends are safe. Low O2 requires around 100ft and then it is safe