Nitrox vs Air

[UaVaj]

My gathering of infomation from all "on topic" posts.

I think it would be safe to say: Using the guideline of the smart Z/computer as the baseline for a controled consistent asending of 30ft/min. Since everyone's absorbtion rate and gassing off rate is different.

For some - the typical asend rate of 30ft/min is more than sufficent for proper gassing off. So it don't matter if they use nitrox or air. They feel the same. So this group there is no benefit to using nitrox.

For others (me included in this group) - the typical asend rate of 30ft/min is insufficent for proper gassing off. So I need to either (1) slow down my asend rate alot more below 30ft/min to allow more time for gassing off or (2) keep my current asend rate of 30ft/min and substitue nitrox so my absorbtion is less to begin with or (3) slow down my asent rate plus substiture nitrox for minimum fatigue. This group should benefit from using nitrox.

 

[in_cavediver]

My gathering of infomation from all "on topic" posts.

I think it would be safe to say: Using the guideline of the smart Z/computer as the baseline for a controled consistent asending of 30ft/min. Since everyone's absorbtion rate and gassing off rate is different.

For some - the typical asend rate of 30ft/min is more than sufficent for proper gassing off. So it don't matter if they use nitrox or air. They feel the same. So this group there is no benefit to using nitrox.

For others (me included in this group) - the typical asend rate of 30ft/min is insufficent for proper gassing off. So I need to either (1) slow down my asend rate alot more below 30ft/min to allow more time for gassing off or (2) keep my current asend rate of 30ft/min and substitue nitrox so my absorbtion is less to begin with or (3) slow down my asent rate plus substiture nitrox for minimum fatigue. This group should benefit from using nitrox.

My opinion only:

1) Change the 'baseline; of 30fpm for your computer to 'max' and shoot for slower

2) Nitrox vs air really is only a part of the equation. Instead, consider inert gas load when discussing the ascent rates and stops. Given your planning and dive monitoring, you are likely to run the NDL's close on whatever gas you are breathing. In that case, nitrox won't help. (except to give longer bottom time).

3) Let me stress this again. Do the ascent smoothly. Avoid the Yo-Yo. A few good techniques in the last ascent (20ft to surface) will IHMO greatly reduce fatigue. This is IHMO more important than the exact ascent rate (within reason), air, nitrox etc.

 

[UaVaj]

I just added two more dive to my belt today. First one was 1 hour at 45ft. 1 hours rest. Second one was 1 hour at 45ft. Didn't feel any post-dive fatigue. This was again with EANx 32.

So far I am buying it. Nitrox is better. More oxygen gotta be better than less oxygen. Once I try air again I should know more.

 

[bdshort]

Just remember, more oxygen isn't better than less oxygen if you go too deep!

A lot of people say they feel better after nitrox, so whether it's real or placebo, if it makes you feel better, then stick with it!

 

[SuPrBuGmAn]

I just added two more dive to my belt today. First one was 1 hour at 45ft. 1 hours rest. Second one was 1 hour at 45ft. Didn't feel any post-dive fatigue. This was again with EANx 32.

So far I am buying it. Nitrox is better. More oxygen gotta be better than less oxygen. Once I try air again I should know more.

Considering you are not running your NDL times on air, much less 32%, you are certainly getting less nitrogen absorbtion than with air.

When your diving improves, quite a bit, and you start getting more respectable bottom times out of those big silo's you've strapped to your back, running your NDL times will be easier and more likely. If you run your NDL times on both air and enriched nitrox, your nitrogen absorbtion will be the same, but you'll get a longer dive with the nitrox which may fatigue you anyway.

Staying within NDL and making a controlled, very slow ascent, will likely reduce any fatigue regardless of O2 content.

At this point in your diving, the Nitrox is only acting as a means to dive will less nitrogen absorbtion. Later on, you may want(and have the SAC rate) to use Nitrox to lengthen the dive itself. If/when you do this, you'll be absorbing more nitrogen than you are currently getting while just diving until your gas supply runs low.

This should have all been taught to you through the Nitrox portion of your class.

 

[TheRedHead]

So far I am buying it. Nitrox is better. More oxygen gotta be better than less oxygen. Once I try air again I should know more.

It its not more oxygen - it is less nitrogen. Trimix works on the same premise.

 

[Blackwood]

It its not more oxygen - it is less nitrogen. Trimix works on the same premise.

But for a different goal.

 

[Lehmann108]

You and I have pretty much done the same amount of diving. I've only used air. At first I was amazed at the effect of the nitrogen loading: I felt fatiqued, spaced out, weak. But the effect became less and less with each successive dive. By the way, I also ascend slowly, in fact, as we speak, I'm still ascending from a 60 foot dive during the Eisenhower administration.

 

[froggs]

...
When the DM finally started to ascend with the rest of the group I signalled him that his group had significant deco and showed him the stops that I estimated they should be doing on my table.
He took a while to catch on but finally held the group for a semblance of a stop, complicated by the fact that there were some divers already below 50bar.
...

I'm curious...how do you signal a deco stop is necessary??

 

[Meng_Tze]

I'm curious...how do you signal a deco stop is necessary??

fist with pink extended.

But that is 'one school of thought'