Geezer Gas

[drrich2]

Octopusprime:

If I understand correctly, when people breathe nitrox (with % O2 > 21%) or pure oxygen, it's not the oxygen that's speeding the decompression; it's the lower nitrogen.

Nitrogen diffuses out of our bloodstream into the air in our lungs. The greater the difference in nitrogen concentration between our blood & the air in our lungs, the faster the nitrogen diffuses out of our blood.

So, the issue is not how much oxygen is in your breathing mix. The issue is how little nitrogen. Air has roughly 79% nitrogen. Any breathing gas you use with a nitrogen content lower than 79% should speed the rate at which you off-gas nitrogen, speeding your decompression.

Richard (not a technical or deco. diver, so hope I got that laid out right).

 

[Akimbo]

MaxBottomtime

That is true during the dive but less a factor on ascent. The problem switches from minimizing the rate Nitrogen is absorbed to maximizing the rate that Nitrogen can be removed from the blood so bubbles don’t form.

Edit: Octopusprime:

Here is a small excerpt from a post you might find useful:
http://www.scubaboard.com/forums/diving-medicine/440726-oxygen-toxicity-limits-symptoms.html

Why use high oxygen levels and risk oxygen toxicity, ever?​

The simple answer for divers is twofold: Rapid removal of nitrogen and/or helium from the body and reducing diluent gas absorption.

 

[GrumpyOldGuy]

If you think about it, Nitrox is actually not a very good solution because of the high oxygen content. It is however relatively cheap to produce when compared to diving with helium. Its also pretty simple to use safely withing rec diving profiles and the depth limit keeps most stupid divers from diving at depths they should not be.

 

[Aquavelvet]

^ In terms of reducing inert gas absorption, though, it's pretty much the only option. (CO2 and Argon are both highly narcotic.)


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[kelemvor]

Placebo affect or not, I think it's worth the few extra dollars per tank to dive nitrox every time it's available. When custom mixes are available I calculate and buy "best gas."

 

[BRT]

Placebo it may be but staying further away from NDC's can't be all bad. I just got back from Mexico. When I can I dive with native fishermen. They dive most dives as decompression dives. I dove with them this year using larger nitrox tanks that pretty much let me dive with them without me exceeding NDC's and running out of air. One day we ended up with 2 extra tanks of 32% and they used them for decompressing. The safety diver took the nitrox down to them as they were hanging. Sure enough, that night they volunteered that they felt better after decompressing with the nitrox. The placebo affect seems to cross language and knowledge barriers also.

 

[GrumpyOldGuy]

If you are diving Nitox tables / computer, you are not staying any further away than if you are diving air on air tables / computer. You are only going to be "safer" if you dive nitrox using air tables / computer.

 

[TMHeimer]

There are a number of anecdotal claims. It hasn't been definitely proven. Then again, if you only believe what has been established via the scientific method to a standard acceptable for professional journal publication, you may have a limited scope of knowledge indeed.

It's a fairly inexpensive, easy course. Try it. Do some repetitive dives. Maybe you'll feel substantially better. If so, maybe it's a 'legitimate' physiological effect that's yet to be established yet is no less real for that. Or maybe it's psychosomatic.

What do you care?

You feel better, you feel better. Who takes Tylenol for a headache and really cares what the mechanism of action was, as long as the headache went away?

Richard.

Agree. I confess to not reading every post. My 2 cents is I rarely dive nitrox but can't recall it making me feel better or different. Regarding the CO2 stuff, I can't recall having any breathing problems on either air or nitrox yet.

 

[Nemrod]

If you are diving Nitox tables / computer, you are not staying any further away than if you are diving air on air tables / computer. You are only going to be "safer" if you dive nitrox using air tables / computer.

And if you are setting your computer for an air dive to provide the deco safety factor then you are not accounting foe the other factor the computers track, o2 exposure.

Nitrox is a useful tool for intermediate depths, I usually feel more fatigued with nitrox on such dives because I can stay in the water longer.

N

 

[GrumpyOldGuy]

And if you are setting your computer for an air dive to provide the deco safety factor then you are not accounting foe the other factor the computers track, o2 exposure.

Nitrox is a useful tool for intermediate depths, I usually feel more fatigued with nitrox on such dives because I can stay in the water longer.

N

Can you provide a realistic profile of dives where staying within the air NDL's also allows you to max out the CNS clock?