Geezer Gas

[BRT]

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.

If I'm diving nitrox on nitrox tables and coming up with more no decompression time than I would diving air on air tables I believe I will be safer. In fact that is my experience.

 

[Storker]

If you are diving Nitox tables / computer, you are not staying any further away than if you are diving air on air tables / computer.

Well, that really depends on you gas consumption and how much gas you carry, doesn't it?

You're assuming that you're carrying enough gas to be able to dive close to the nitrox NDL, and that's not always the fact. At least not for me. With a normal Euro-sized rec tank (which holds about 10% more gas than an Al80), in my drysuit and in Nordic water, my air NDL time and my gas limited bottom time correlate pretty well. At least if I want to stay within min gas limits.




--
Sent from my Android phone
Typos are a feature, not a bug

 

[Angry Turtle]

I don't know if this is a myth or not but a lot of divers would come onboard for a crew change after their last night onshore for the next month and after a little too much libation. They all swore that a single 20 minute cycle at 60% on pure O2 was the cure for hangovers. It got to be more trouble to debate it than just blow them down in the double lock. They were happy when they came out and everyone went back to work.

It would have been nice if possible to send them in, but without their knowledge keep them at 21%. If they came out and acted all refreshed, you would know.

 

[drrich2]

An old Family Doctor I knew years ago, speaking to which condition a patient might have, commented that 'It's possible to have both ticks and fleas.'

I am confident there is a placebo effect for some people knowingly diving nitrox. Just as I'm confident there's a placebo effect for some people taking Tylenol or Ibuprofen for a head ache. But just as those med.s do have non-placebo effectiveness, nitrox may also.

Richard.

 

[Searcaigh]

It would have been nice if possible to send them in, but without their knowledge keep them at 21%. If they came out and acted all refreshed, you would know.

When I was worked in a hospital labs not so long ago, it was common for some techs to lay on the blood donor bed and breath 100% O2 for about 15-20 mins the morning after a heavy night on the grog, myself included. Seemed to do the trick along with a Brufen too of course.

 

[Akimbo]

It would have been nice if possible to send them in, but without their knowledge keep them at 21%. If they came out and acted all refreshed, you would know.

We talked about that but didn't want to [-]screw up[/-] contaminate the Oxygen clean system on the chamber. Strange as it may sound, most surface-supplied diving jobs don't have HP compressors. The only HP air we had was in fairly limited quantities stored in industrial cylinders to cascade into bailout bottles. Air dives and the chambers are supplied by two or more high volume low pressure (70-90 CFM @ 150-175 PSI) compressors.

 

[GrumpyOldGuy]

Well, that really depends on you gas consumption and how much gas you carry, doesn't it?

You're assuming that you're carrying enough gas to be able to dive close to the nitrox NDL, and that's not always the fact. At least not for me. With a normal Euro-sized rec tank (which holds about 10% more gas than an Al80), in my drysuit and in Nordic water, my air NDL time and my gas limited bottom time correlate pretty well. At least if I want to stay within min gas limits.




--
Sent from my Android phone
Typos are a feature, not a bug

So you are relying on the chance that your air consumption / air supply just happens to match air NDL in your typical dive?

Given enough dives in different environments and experience which generally improves gas consumption, we all hit NDL's eventually. Relying on your current air use, tank size and environment to keep you at parity with air NDL seems like a lack of planning. Its kind of like the divers who think its time to surface at XXX PSI/Bar because it worked for them in the past. Eventually, something changes and that XXX value is no longer valid.

 

[Akimbo]

I just wanted to add that reducing fatigue is pretty low on the list of good reasons to use Nitrox. Placebo effect and/or disparaging titles are minor when used in the proper applications.

OK, 40% Nitrox for single dive to 40' a day is nice but of debatable value. Few will argue that Nitrox does optimize your underwater time when making multiple dives per day that are anywhere close to NDLs.

 

[Storker]

So you are relying on the chance that your air consumption / air supply just happens to match air NDL in your typical dive?

Not at all. I keep track of both NDL and min gas pressure when I'm diving. They just happen to match when I'm on a normal dive in cold water and in a drysuit.

My argument was that your gas reserves may not allow you to dive as close to the NDL when you're on nitrox, at least if you manage your gas better than "be at the surface with 50 bar left". Ergo, you'll have better margins WRT nitrogen saturation if you're on nitrox than if you were on air.

 

[GrumpyOldGuy]

Not at all. I keep track of both NDL and min gas pressure when I'm diving. They just happen to match when I'm on a normal dive in cold water and in a drysuit.

My argument was that your gas reserves may not allow you to dive as close to the NDL when you're on nitrox, at least if you manage your gas better than "be at the surface with 50 bar left". Ergo, you'll have better margins WRT nitrogen saturation if you're on nitrox than if you were on air.

You are still working with the assumption that you MIGHT be gas limited which should then result in having a gas saturation difference.
My point is you don't know that you will be gas limited, the assumption is dependent on multiple variables.
This is different from diving nitrox on air tables where you WILL have a gas saturation difference no matter what variables you plug in.