Why not air?

[jefffalcone]

I just finished my fundies class, and the only thing that doesn't make much sense to me is the prohibition of diving air. I simply can't see the benifit of diving nitrox 32 for a 30 minute shore dive to 30 fsw. If the arguement is that less nitrogen loading is always better, why not optomise mixes? Why only 32. The explaination I got for not optimizing mixes is that the benifit is minimal. Doesn't this logic carry over into just diving air for short shallow dives?

The class is long and they cram in a lot of information. This is the one point that didn't seem so logical to me in a system that otherwise is completely logical. Maybe I missed the point, or there wasn't time to adequately cover it.

 

[Sloth]

Diving air is stupid... we always opt for EAN 21 as a replacement. We even used EAN 21 in our fundies class. /snark

 

[TSandM]

The simple answer is that there is very little benefit to diving Nitrox for a 30 minute dive to 30 feet.

But one of the things that is nice about standard gases is that there's no uncertainty. All the members of the team are on the same gas, and therefore have the same deco schedule. Since I dive extensively with other GUE/DIR divers, I often forget to ask people what gas they're breathing, and it becomes problematic when I've forgotten to do so and we ARE diving deep enough that the MDLs are different. Also, if you always dive 32%, then when you grab a tank at home, you aren't going to have the unpleasant surprise that today, when you want to go to 100 feet, you've accidentally grabbed your air tank.

If I were in a situation where I had to drive an extra hour to get Nitrox, or pay double for it every time I topped off a half-full tank, I might exercise some discretion in when and where I used it, despite the recommendation to be on 32% all the time. I'm lucky; I have an "all you can eat" Nitrox deal, and the shop is convenient to my house and usual driving routes. (BTW, the preceding statement is NOT DIR, as you know. I'm just pointing out that I can follow this particular recommendation easily because it's no hardship to me.)

 

[Walter]

Is there really a prohibition on diving air?

 

[Jason B]

We were taught air is for tires.

 

[Walter]

We were taught air is for tires.

Perhaps, but it doesn't answer the question. There are lots of options for breathing mixes. I personally believe the best mix varies from dive to dive depending on the circumstances. I've heard some people do not ever dive air, but this is the first time I've ever heard an agency (GUE) has prohibited it's use. I would like to know if that is a fact or an unfounded rumor.

 

[amascuba]

Perhaps, but it doesn't answer the question. There are lots of options for breathing mixes. I personally believe the best mix varies from dive to dive depending on the circumstances. I've heard some people do not ever dive air, but this is the first time I've ever heard an agency (GUE) has prohibited it's use. I would like to know if that is a fact or an unfounded rumor.

There are not GUE police that are going to revoke your GUE credentials for diving air. At a recreational level (0 - 100 feet) it's not prohibited. It's just recommended that you use EAN32.

 

[TSandM]

As with so many other things about DIR, you are given the recommendations and the reasons why, and you go off to make your own decisions. If you are doing a "DIR dive", you will be on 32%. If you are faced with a situation where you cannot get 32%, you have a choice -- If you're super hard core, you sit the dive out. If you're like the rest of us, you shake your head and go diving

I think it gets much more important when you start talking about deeper dives and the use of helium.

 

[ppo2_diver]

Another reason why 32% was chosen, was that you can make standard mixes with 32% top off. If I wanted to dive 18/45, I put the helium in and top with 32%. As Lynne said, it's a standard gas that lets us dive to any GUE recreational limit. I said GUE recreational limit, which is shallower than the 130 foot industry limit.

 

[rongoodman]

On my first go at Fundies the shop gave me air without comment, simply because they did partial pressure fills and my tanks weren't cleaned for them. I analyzed and labeled my tanks like everyone else. They're not going to drum you out of class for breathing air, but they have good reasons for recommending standard mixes.