100% oxygen, safety stop depth & off gassing

[Dr Deco]

Oxygen and Off gassing - - -

If there is not any decompression obligation, as in recreational diving, then oxygen at depth is not a requirement, likewise. If you wish to increase dissolved nitrogen elimination from tissues, then what is really desired is nitrogen-free blood flow for as long a duration as possible. This is accomplished best by breathing at the surface. This will maximize the breathing time and the give a longer duration for tissue perfusion.

This does assume that there are only a few bubbles present and “squeezing” them [to increase the Laplace pressure] is not really a concern. The constriction and the toxicity factor have been discussed a little earlier by other responders.

Dr Deco :doctor:

 

[DeepSeaExplorer]

As 5 minutes at 20 feet on O2 (1.6 ppo2 BTW) for a safety stop from an NDL dive is total overkill to begin with, I would see absolutely no reason to do additional stops.

Have you been trained to use O2?

Absolutely...

From other posts, it appears this individual has no training and cannot calculate PPO2 correctly. There is no reason to be doing 8 minutes on O2 for a no stop dive. That's roughly equalivent to doing a 16 minute safety stop on back gas. Overkill...

This guy is trying to learn how to deco dive on the Internet. No one should help him by entertaining his questions and no one should be giving him O2.

 

[z3r0c00l]

The greatest gradient is 10 feet and above. So 10 ft stops are very helpful if you can take them, but sometimes water conditions do not allow that. Better to do a stable 15 ft stop than a bouncy 10 ft stop in waves.

Ideally, you will take your 10 minute stop, and then crawl up a gentle slope slowly. Finally, you should slowly pull your body out of the water, legs first then work your way up to the head. Towel dry slowly so the weight of the water film isnt removed too quickly.

All joking aside, if O2 or nitrox is being used to make your dive safer, you should pretend it is air and not assume you are offgassing more quickly. That isnt exactly the kind of science you are prepared to make on a non-decompression dive. It is not clear how the statement that O2 is 2x as good as air for decompression came about, but you should not think like this.

Better off sticking to air the whole time, or using O2 and pretending it is air (for offgassing affinity, not PO2 dangers). Skipping stops or making them shorter than on air is asking for trouble if for some reason Oxygen isnt the silver bullet you had expected, not to say you are at any huge risk to begin with if you dive by the rec tables or a conservative computer.

I have to ask, why do people hate air so much? Cheap, reliable, doesnt explode, tastes great, good to 190+ feet... Could it be that sometimes having extra tanks looks cool?

 

[Kevfin]

I read this article last year. It pertains to medical use of 100% oxygen and dealt with children.
The dangers are clear and there are implications for adults and divers. Many European countries have stopped using 100% oxygen medically because they are aware of the changes to the brain that occur.

Pure Oxygen Is Bad for Your Brain

Wow, with that said, I do not have a problem using 100% O2 for technical dives were it is part of your planned deco and you are trained to do so. But, to throw it in when you are within recreational limits, along with the potential dangers of operating close to a 1.6 PP02 makes no sense.