Nitrox vs. Regular Air?

[herman]

As far as I am concerned both of the shops are wrong. Like everything else nitrox has it's place. It's not necessarly for tech diving but it does have a place there. On the other end, there are plenty of times it makes no sense to use it. On trips to Bonaire I use it due to the diving I am doing. My dives are no where close to tech or close to NDLs but 4 to 6- 60 to 90 minute dives a day over 6 days is a lot of nitrogen loading, any reduction helps. Nitrox keeps me a lot farther from the NDLs, that's never a bad thing. A lot of dive ops there include it at no cost so why not.

On coastal trips it's useful because of the longer NDLs and shorter SI's (NC dives tend to be on the deep side). On shallow reef dives in Fla where I am at 30 ft for 2 dives for a couple of days or doing a few quarry dives on a weekend, it makes no sense. There is no way I am going to be close to any NDL so there is no advantage to the reduced N2 loading. Why pay the extra cost.
Nitrox has it's place. It's not some voodoo tech gas but it's not a cure all either. Use it when it makes sense to use.

 

[Zoomer]

The advantage of nitrox is that the diver off gasses quicker.

Actually, you do not off gas any quicker. Your ending Nitrogen load is lower with a dive at equal depth. If you remember from your class you can calculate what your EAD is (Enhanced Air Depth) and use the standard dive tables.

In other words, if you where diving EAN36 to a depth of 70 feet, you nitrogen load is equivalent to diving air (21% O2) to 50 feet.

 

[The Kraken]

Granolatree,

This is a VERY BROAD GENERALIZATION, but for most recreational divers, the only practical purpose nitrox serves is to reduce the surface interval time between dives.

You see, you go on a dive trip, you rent tanks. What are those tanks going to be??? 80 cu. ft. aluminum tanks.

Two things will be pretty much constant, the volume of the tank you're diving and your SAC rate (surface air consumption rate - the amount of air you breathe per minute).

Your breathing gas consumption does not change between air and nitrox, you're going to breathe that which you're going to breathe.

Let's just say you're excited and anxious about your dive and you're using 6/10th's of a cubic foot of gas per minute (SAC rate of 0.60).

Your dive depth is 70' (assuming a square dive profile and residual gas of 500 psi upon surfacing).

With an aluminum 80, you're going to get about 34 minutes bottom time. The NDL on air for 70' is 40 minutes. This means you're going to run out of gas before you max out your bottom time.

Now, if you were to do that same dive but using EAN32 (32% O2), your NDL would be 60 minutes !!!!

But keep in mind that your tank holds only 34 minutes worth of breathing gas!

So, since you really can't extend your bottom time predicated upon the volume of your tank, the practicality of diving nitrox, in this scenario, falls into the area of reducing your surface interval time for the next dive.

the K

 

[espenskogen]

Actually, you do not off gas any quicker. Your ending Nitrogen load is lower with a dive at equal depth. If you remember from your class you can calculate what your EAD is (Enhanced Air Depth) and use the standard dive tables.

In other words, if you where diving EAN36 to a depth of 70 feet, you nitrogen load is equivalent to diving air (21% O2) to 50 feet.

It's actually equivalent air depth, but the principal is correct.

 

[String]

Its OK if you find your dives are being limited by no stop times rather than air consumption (be that a single dive or a series) - THEN you'd benefit from Nitrox.

Otherwise there's no point unless you get it for the same price as air.

None of the other things have been proven to exist (alleged safety margin, alleged lack of fatigue etc)

 

[Age]

Maybe this is slightly off topic, but I did the PADI Nitrox course and I thought it gave me everything I needed when I took out a couple of tanks in Puero Gallera. But the material is in just a pamphlet really, and I noticed the the NAUI Nitrox course-book looks like 'War and Peace". What was I missing out on?

 

[123Scuba.com]

I'm wearing a tee shirt with the slogan "if you understood nitrox you'd be diving it too".

Says it all really.

Love it... -That is one of the better ones I've heard in a while (and I do hear quite a few.)

 

[TSandM]

Maybe this is slightly off topic, but I did the PADI Nitrox course and I thought it gave me everything I needed when I took out a couple of tanks in Puero Gallera. But the material is in just a pamphlet really, and I noticed the the NAUI Nitrox course-book looks like 'War and Peace". What was I missing out on?

I've never seen the PADI materials, but I thought the NAUI Nitrox book was a very well-written and thorough educational resource. There's a fair bit of information about the history of Nitrox use, and a fair bit of physiology, and quite a few calculation examples.

 

[ClayJar]

Otherwise there's no point unless you get it for the same price as air.

None of the other things have been proven to exist

Perhaps there have not been sufficiently large, sufficiently controlled studies to statistically validate particular results of diving nitrox, but saying that there is no point other than NDL strikes me as "greedy reductionism".

If lower nitrogen loading reduces the likelihood of DCS for any given dive (with respect to doing an identical profile in identical conditions, environmental and physiological), then it follows that using nitrox instead of air must have that benefit. As that is a fundamental principle (although not necessarily the only fundamental principle) behind the tables and computer algorithms, the position that nitrox does not reduce the likelihood of DCS is untenable. Now, that is not to say that the health or safety benefits of diving nitrox reign supreme. Nitrox makes you slightly safer (just like cutting your NDL would make you slightly safer), but a quick ascent may vastly overwhelm any benefit you may have added. For the average recreational diver, the signal may be lost in the noise, but that is no reason to deny the signal, even if concentrating on the noise provides more return on the effort invested.

(The alleged lack of fatigue, however, will indeed require quite a few more scholarly works before conclusions may be reached and validated. It seems apparent to me that the fatigue is most likely sub-clinical DCS brought on by non-optimal ascent profiles, but I would not consider my paper reading and informal observations and interviews of a few dozen divers over a couple dive seasons to be anywhere near the quality of study needed to tease out the data.)

Maybe this is slightly off topic, but I did the PADI Nitrox course and I thought it gave me everything I needed when I took out a couple of tanks in Puero Gallera. But the material is in just a pamphlet really, and I noticed the the NAUI Nitrox course-book looks like 'War and Peace". What was I missing out on?

War and Peace? I just checked my books, and NAUI Nitrox Diver is only 103 pages, cover to cover. (That's compared to NAUI Scuba Diver at 234 pages, NAUI Advanced Scuba Diver at 105 pages, NAUI Rescue Scuba Diver at 195 pages, and NAUI Master Scuba Diver at 291 pages.) The chapters are:

1. Introduction (p. 2-13) The history, myths, misconceptions, etc.
2. Gases and Gas Mixtures (p. 14-29) Gas properties and physics.
3. The Physiology of Diving and Nitrox (p. 30-41) DCS, (CNS and pulmonary) oxtox, hypoxia, and everything in between.
4. Choosing the Best Nitrox Mix (p. 42-51) MODs, how to calculate the best nitrox mix for any given depth, etc.
5. Dive Tables and Dive Computers (p. 52-64) Nitrox tables, RGBM tables, computers, etc.
6. Oxygen Precautions and Preparing Nitrox (p. 66-77) Handling oxygen and cylinders, different fill methods, your responsibilities.
7. Knowing What You Breathe (p. 78-83) Analyzing, labeling, logging, etc.
8. (Glossary, Tables, Formulas, Dive Tables, and the Index cover the rest)

I don't have the stuff you used for your PADI Nitrox, but that's my quick summary of what was in the book. (Perhaps if granolatree's local shops would take some time to read it through, there wouldn't be so many apparently flawed ideas flying around.)

 

[ACR]

I just took the NAUI course and I thought it was a well written manual and a lot quicker read than War and Peace. Admittedly though I did find War and Peace to be a little lacking in details around the use of equivalent air depth tables.

My suggestion would be to take the course. It tends to be a pretty low cost one, and it's fairly short so you're not out much money or time if you decide that devil gas... er, I mean EAN is not for you.