44 replies to this topic

[PerroneFord]

There's no reason to cringe if the diver is using air.

Yea... but who'd do THAT???

LOL!

[Moderator note: Air/Gas discussion split from the discussion regarding scuba terminology.]

[Walter]

I use it frequently.

[PerroneFord]

I use it frequently.

I'm sorry.

[Walter]

I'm sorry.

About?

[PerroneFord]

Sorry about you diving air. But hey, if you like it...

[jextract]

Beats diving WITHOUT air!

[Walter]

Why would you use anything else on a 20 ft dive?

[PerroneFord]

Lets see:

1. The narcotic value of air is higher than any other commonly available breathing gas.

2. The extreme amount of intert gas in air increases its risk of DCS on shallow dives

3. Air has an incredibly poor value as a decompression gas.

4. Because of the different grades of air, using it may contaminate my oxygen prepared tanks necessitating recleaning (expensive and time consuming)

5. Better breathing gases are available for a minimum cost premium in many cases.


Again, these are my reasons. Some or all may not be applicable to others.

[Walter]

1. The narcotic value of air is higher than any other commonly available breathing gas.

No more narcotic than nitrox. This argument only applies if you are comparing air to trimix or heliox. Besides, if the dive is to 20 ft, the narcotic effect is not a factor.

2. The extreme amount of intert gas in air increases its risk of DCS on shallow dives

On dives to the same depth for the same time, all other factors being equal, one will be at greater risk of DCS on air than on EAN. OTOH, you are at a much greater risk of DCS diving EAN to 80 feet than air to 20 feet. Unless you keep all your dives extremely shallow, you already put yourself at greater risk, the argument doesn't hold water. There are two ways to guarantee you'll never get bent - 1. don't dive - 2. if you do dive, don't come up. This argument is silly.

3. Air has an incredibly poor value as a decompression gas.

The question wasn't, "why don't you decompress on air," but, "why don't you dive on air?"

4. Because of the different grades of air, using it may contaminate my oxygen prepared tanks necessitating recleaning (expensive and time consuming)

Of course all O2 clean tanks should only be filled using modified grade E air, the exact same air that is put in your tanks when you get a pp EAN fill. There's no difference to the tanks if the air goes in by itself or on top of O2.

5. Better breathing gases are available for a minimum cost premium in many cases.

There are times when EAN is a better choice, in those cases, it makes sense to use it. There are places (not many) where EAN and air cost the same. In those situations, I agree, use air, but for shallow dives where EAN costs more, there's no reason to pay extra for it. Air is just as good for a 20 ft dive as EAN.

Edited by Walter, 18 August 2006 - 01:04 PM.

[jextract]

Cost for air fill: $4
Cost of Nitrox fill - 32% $10.00
Cost of Nitrox fill - 36% $12.00
Cost of Nitrox fill - 40% $15.00
Cost of Nitrox fill - 50% $20.00

So for the same money I can dive at least 2.5 times more often, not even counting the O2 cleaning cost. Additionally, the vast majority of dive boats here fill air and not nitrox (the Peace is an exception).

I'd say for the type of diving that most of us do, that's a pretty compelling argument.

[PerroneFord]

Cost for air fill: $4
Cost of Nitrox fill - 32% $10.00
Cost of Nitrox fill - 36% $12.00
Cost of Nitrox fill - 40% $15.00
Cost of Nitrox fill - 50% $20.00

So for the same money I can dive at least 2.5 times more often, not even counting the O2 cleaning cost. Additionally, the vast majority of dive boats here fill air and not nitrox (the Peace is an exception).

I'd say for the type of diving that most of us do, that's a pretty compelling argument.

Here was my comment:

5. Better breathing gases are available for a minimum cost premium in many cases

Please note that I did not say ALL cases, or even a majority of cases. I said many cases. In my own case, I pay no more money for nitrox than air at my local shop. At the shops within a 100 mile radius where I fiil, nitrox costs $.07 per cubic foot and air $.04. So for an absolutely empty AL80 its $5.42 for nitrox $3.10 for air. The extra $2.32 doesn't bother me that much. And since I don't fully drain my tanks, filling up my doubles away from home generally costs me about $6-$8 for Nitrox.

Of course, not everyone has these advantages. For some, an extra $6 to fill with nitrox is cost prohibitive. I guess if you've spent $600 for a dive trip, spending an extra $30 for nitrox is a lot.

Edited by PerroneFord, 18 August 2006 - 01:06 PM.

[PerroneFord]

Ok Walter you win.

[Walter]

At Fill Express in Pompano, nitrox costs the exact same amount as air. When I'm in that area, I get nitrox, but elsewhere, I evaluate the value of nitrox. Often, it has no value over air, so I don't pay more for it.

[gcbryan]

On vacation with mulitple dives over multiple days I may dive Nitrox to air tables otherwise I rarely use it for diving.

Air is free for me at the moment. Nitrox isn't. Most shops around here won't fill my tank unless it is "cleaned" for Nitrox but where I get my free air the air isn't filtered to Nitrox standards (seperate compressor for Nitrox) so unless I always dive Nitrox or keep 2 additional tanks dedicated to Nitrox it's an issue.

[ScubaDadMiami]

I use whatever efficiency on the dive calls for: air, EANx, Trimix and/or oxygen. (I might even start to use Heliox in my diluent tank for the CCR.) However, it has been only on an extremely rare occasion that I have used air in the last five years.