Air then Nitrox

[Lamnid]

The other day I was diving with regular air. As is my way, I was nearly out of air after 30/40 mins. So i buddy breathed with my instructor who was on a Nitrox tank. Everything was cool but I was wondering to myself at the time - is it okay to switch from air to Nitrox underwater? Well I can't think of any reason why not but what do you guys think?

 

[Walter]

It's fine.

Why did you buddy breathe, didn't he have an octo?

 

[limeyx]

The other day I was diving with regular air. As is my way, I was nearly out of air after 30/40 mins. So i buddy breathed with my instructor who was on a Nitrox tank. Everything was cool but I was wondering to myself at the time - is it okay to switch from air to Nitrox underwater? Well I can't think of any reason why not but what do you guys think?

I think you have bigger problems than breathing some Nitrox

"As is my way, I was nearly out of air after 30/40 mins. So i buddy breathed with my instructor"

 

[Lamnid]

yeah i chew through my air! I'm not ashamed though - I'm proud lol. Believe me...I'm working on this! Oh and sorry - when I say buddy breathe I meant we just shared from the 2 regs. Wrong terminology - my bad.

 

[616fun]

Air to nitrox isn't an issue so long as you weren't pushing the operating depth of the gas. Since your instructor was using it I'd say that wasn't an issue - but discuss air mgmt with your instructor. Air sharing is for emergencies only. There is no reason you should be required to share air on a dive if you and your buddy are managing your air appropriately.

 

[scububa]

The other day I was diving with regular air. As is my way, I was nearly out of air after 30/40 mins. So i buddy breathed with my instructor who was on a Nitrox tank. Everything was cool but I was wondering to myself at the time - is it okay to switch from air to Nitrox underwater? Well I can't think of any reason why not but what do you guys think?

This isn't meant to be overly harsh, but it would seem to me the answer is that you shouldn't switch to anything that you have to wonder about unless it is a 'no option' situation. Being with your instructor, I would hope this was not the case.

Divers switch gas under water all the time. Especially when doing deco stops. But, they are trained and usually on a planned schedule. Normally, they are switching to Nitrox (maybe 50%, maybe higher). They may or may not be coming off of 'natural nitrox' (air).

I enjoy my diving quite a bit more when I am not wondering, "Am about to hurt myself?"

 

[Lamnid]

Nah I mean I totally trust my instructor, he knew I was on air and that he was on Nitrox so obviously I went with it. It's just something that I briefly pondered on at the time. I mean, I just like to know all the effects of everything related to diving so if I query something even for an instant, I have to know the answer! lol.

 

[limeyx]

yeah i chew through my air! I'm not ashamed though - I'm proud lol. Believe me...I'm working on this! Oh and sorry - when I say buddy breathe I meant we just shared from the 2 regs. Wrong terminology - my bad.

I think you are mis-understanding me. What would happen if your instructor was also chewing through his/her air and came to you at the same time?

You need to reserve enough gas to get you & your instructor safely to the surface.
It seems you view sharing air to get up as a somewhat "normal" thing, and that is dangerous.

 

[Fotoz4FX]

Okay... since no-one has actually answered your question, how about if I do it? Fact is that you (on air) could dive deeper than your instructor though for a shorter period of time without going into a deco dive scenario which if low on air would have been deadly in your case but that WAS NOT the case since he was on Nitrox (he can't dive as deep as someone on Air because after 218 feet Oxygen becomes toxic and he was diving enriched).
The fact that your instructor was on Nitrox mix (you didn't mention the EAN but that's not really important) informs us that the dive was within your recreational dive limits and certainly within the limits of his mix.
Your concern naturally is nitrogen loading which, when breathing Air is quicker to build at the approximate 79% as opposed to his mix which would be somewhat less (if EAN is 32 then Nitrogen is around 68) which gives him a longer time at the depth you were.
I presume he shared air with you because he didn't want to abort the dive... I've done it and I'm sure hundreds of other instructors have done it too... it doesn't make you a bad instructor nor a poor diver... you signaled that you were low and needed to surface and I'm pretty sure your instructor had plenty left to share and continue your dive.
No need to slap your hand... I think it was obvious what was going on.
Nitrox reduces the nitrogen buildup therefore you were fine breathing it - in fact, if you guaged your dive on 21% either by your RDP or off your computer, you were WELL within the safety zone when you returned to the surface.

My hats off to you for not panicing and for trusting an instructor who I feel was in full control of the situation.

 

[ArcticDiver]

Okay... since no-one has actually answered your question, how about if I do it? Fact is that you (on air) could dive deeper than your instructor though for a shorter period of time according to your dive tables.
The fact that your instructor was on Nitrox mix (you didn't mention the EAN but that's not really important) informs us that the dive was within your recreational dive limits and certainly within the limits of his mix.
Your concern naturally is nitrogen loading which, when breathing Air is quicker to build at the approximate 79% as opposed to his mix which would be somewhat less (if EAN is 32 then Nitrogen is around 68) which gives him a longer time at the depth you were.
I presume he shared air with you because he didn't want to abort the dive... I've done it and I'm sure hundreds of other instructors have done it too... it doesn't make you a bad instructor nor a poor diver... you signaled that you were low and needed to surface and I'm pretty sure your instructor had plenty left to share and continue your dive.
No need to slap your hand... I think it was obvious what was going on.
Nitrox reduces the nitrogen buildup therefore you were fine breathing it - in fact, if you guaged your dive on 21% either by your RDP or off your computer, you were WELL within the safety zone when you returned to the surface.

My hats off to you for not panicing and for trusting an instructor who I feel was in full control of the situation.

Gosh, a straight, accurate, non-critical answer! Will SB survive the shock?