[quote]rrjc5488 wrote:
jsbrook wrote:
undeadlift wrote:
jsbrook wrote:
Oxygen is certainly not toxic at surface pressure. Who actually dives on pure oxygen and why? As opposed to being treated with it at surface for suspected decompression sickeness. Just curious. Nothing I’ve heard of and I’m a certified dive master. Sorry to the OP for the tangent.
Are you a tech diver as well?
No. This is why I’m curious. Most technical diving seems to be done at deeper depths. I had thought oxygen toxicity occurs at 13 meters. If it indeed occurs at 19 ft as someone said, it would seem even less useful for tech diving. I suppose some applications of technical diving might be done closer to the surface. But most technical divers also use rebreathers which allows you to stay under almost indefinitely. Certainly much longer than air, nitrox, or pure oxygen would allow. So, I really can’t imagine a useful application.
To answer your first question: no one actually “dives” on pure oxygen, they decompress on pure oxygen.
Yes, almost all tech diving is done at deeper than recreational diving. You obviously wouldnt use nitrox going deeper than 130ft, so you would either dive air (not the best idea) or trimix (your best option for open circuit diving.)
Deep diving obviously has smaller no decompression time limits than shallow diving, and keeping your dive mix the same (lets use air: 21% oxygen, 79% nitrogen) you’re going to build up a decompression requirement faster at a deeper depth than at a shallow depth.
Tech divers plan their dive knowing that they’re going to pass no deco time limits. After their “dive,” they ascend into shallower waters to decompress and let the nitrogen dissolve out of solution in the blood. Tech divers carry their primary dive gas blend usually in doubles on their back, and then deco stage bottles filled with a gas blend higher in oxygen content. An example would be 50% oxygen/50% nitrogen, that they’ll breath at say 60 feet for X amount of time, then will ascend to ~15 feet and breath 100% oxygen to get rid of nitrogen even faster.
A rebreather is just a whole new ballgame. The things are unbeleivable. Its basically diving with a nitrox blending station on your back, and a seemingly bottomless air supply.
I really dont mean to be a dick, and I dont intend to… but you’re a certified DM and havent heard of accelerated decompresion?
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What do you mean? Of course I know all about decompresion and nitrox and trimix. And tech divers are not the only ones to used staged decompression, either. We also use multiple decompression stops for deep dives. I did not know the exact percentage of mix common in use for tech diving, but I knew that it was higher that the 36% nitrox we often use for commerical diving. My only question was ‘who dives on pure oxygen and for what purpose?’ And apparently the answer is nobody. Apparently, some tech divers breathe pure oxygen at their last decompression stop. So, while, I know about decompression diving obviously, I guess I don’t know about accelerated decompression in the sense you are talking about. This is interesting to me and why I asked the question. But it has no real application for my own diving. Tech diving and commerical diving are very different animals.