Nitrox Certification?

[toodive4]

Benefits ... some extra bottom time and some say a little more energy after a day of diving. Personally I don't see either benefit as significant enough to justify the extra expense of paying for Nitrox. I've been Nitrox certified since 1998 and haven't used it since 1999. The people I dive with using Nitrox come up from theire dives at the same time I do... and I can still run circles around them.

Nitrox is not bad... and has its place for some people doing some types of diving... but I do not recommend it due to cost. I don't believe the cost outweighs the benefits. Others will disagree... You must also remember that EAN Nitrox has MOD's (Maximum Operating depths.) If you doing any type of deeper diving this can be a problem and can lead to Oxygen Toxicity - so it is imperative you understand it before you use it.

Ken

 

[Canadian_Diver]

Benefits ... some extra bottom time and some say a little more energy after a day of diving. Personally I don't see either benefit as significant enough to justify the extra expense of paying for Nitrox. I've been Nitrox certified since 1998 and haven't used it since 1999. The people I dive with using Nitrox come up from theire dives at the same time I do... and I can still run circles around them.

How about added safety from DCS? Is Nitrox too expensive then? Or the guy who's getting over the hill and whose arteries are losing their elasticity due to old age?

Ever go for a ride in the chamber? I hear it's not too pleasant.

 

[String]

How about added safety from DCS?

Currently that claim isnt a sensible one to make. Even though common sense would dictate less nitrogen is good, latest research (including DAN) showed the % margin was so small as to be statistically insignificant.

There are various reasons for this including the fact standard tables for recreational diving are very safe but there was no measurable improved safety margin when people investigated it despite this going against what would seem logical - the effect is tiny.

Add that to the fact nitrox costs 3-4x that of an air fill here there are quite a few reasons why its not used exclusively.

 

[toodive4]

There is no added safety from DCS if you extend your bottom time. This goes to the comment about the recent research being marginal. If you stay at depth longer than you would have on air... then the added safety from a higher percent of O2 in the mix goes away. You would have this benefit only if you dove Nitrox as if it were air... and returned to the surface without using your extended bottom time.

Ken

How about added safety from DCS? Is Nitrox too expensive then? Or the guy who's getting over the hill and whose arteries are losing their elasticity due to old age?

Ever go for a ride in the chamber? I hear it's not too pleasant.

 

[DiveGolfSki]

Currently that claim isnt a sensible one to make. Even though common sense would dictate less nitrogen is good, latest research (including DAN) showed the % margin was so small as to be statistically insignificant.

There are various reasons for this including the fact standard tables for recreational diving are very safe but there was no measurable improved safety margin when people investigated it despite this going against what would seem logical - the effect is tiny.

Add that to the fact nitrox costs 3-4x that of an air fill here there are quite a few reasons why its not used exclusively.

I kidded about the benefits of air specifically nitrogen (martini effect) but reducing the risks of getting narced IS a benefit. Clearly, the risk diminishes at shallower depths but I'm sure you know that the science of when someone gets narced isn't precise ... i.e., it is highly variable between individuals.

Paying 3-4x the cost of air is a factor but you get what you pay for. Reminds me of how Bill Nagle viewed mixed gases in the early 90's ... vodoo gas. He eventually relented and joined the club ... of course, that was trimix and that is a whole different discussion but the principles are still the same.

I will admit that if I'm diving in an underwater reef park, in the caribbean, with no current and a maximum depth of 30 fsw ... nitrox would be an overkill. Hell, I'll probably just use a 40 foot snorkle ...

 

[String]

There is no added safety from DCS if you extend your bottom time. This goes to the comment about the recent research being marginal.

I was referring to the nitrox on air tables as opposed to pushing the NDLs for the given mix.

 

[String]

I kidded about the benefits of air specifically nitrogen (martini effect) but reducing the risks of getting narced IS a benefit.

And how do you get that risk reduced given that oxygen is MORE narcotic than nitrogen. Narcosis elimination is not one of the benefits of nitrox.

 

[DiveGolfSki]

There is no added safety from DCS if you extend your bottom time. This goes to the comment about the recent research being marginal. If you stay at depth longer than you would have on air... then the added safety from a higher percent of O2 in the mix goes away. You would have this benefit only if you dove Nitrox as if it were air... and returned to the surface without using your extended bottom time.

Ken

I think we're all mixing our apples and oranges in this discussion. Perhaps, a hypothetical example can help. Let's asssume:

1. a standard 80 cu tank
2. a dive to 99 ft
3. a total bottom time of 25 minutes.
4. a SAC rate of .60
5. all other aspects of the dive are held constant (no current, warm water temps, etc)
6. diver is in excellent physical shape
7. Standard Naui dive tables are used (not RGBM)
8. Compare EAN 21 (air) vs. EAN 32

EAN 21: Requires 5 min deco at 15 ft. Given a SAC rate of .60, he would have 20 cu of air left. At 15 feet, that's plenty of air for a 5 min deco.

EAN 32: Does not require any deco since the deco limits is 30 minutes. A short safety stop would even reduce the risk.

Since the diver on air did his deco obligation, the risk of DCS should be the same ... in theory. Which gas would you risk your life, your family's future (need some violins here ity_part ), your pet's future etc.?

 

[DiveGolfSki]

And how do you get that risk reduced given that oxygen is MORE narcotic than nitrogen. Narcosis elimination is not one of the benefits of nitrox.

What???? Oxygen is more narcotic than nitrogen???? You sure about that?? Check these links out:

http://www.dansa.org/medical/narcotic.html ("However, oxygen is significantly less narcotic than nitrogen ...")

Narcosis elimination is not one of the benefits of nitrox????

Are you talking about toxicity?

Have head theory that unmetabolized oxygen may be as narcotic as nitrogen but recreational divers don't usually subject themselves to oxygen pressures where this could be factor ... right?

 

[String]

Most science would disagree with that:

http://www.techdiver.ws/trimix_narcosis.shtml

http://www.divefortyoung.com/whatisnitrox.html

t is also a common misunderstanding to think that it causes less narcosis. This would be due the fact that it has less narcotic nitrogen. But oxygen is also narcotic, and according to some references it is maybe as narcotic than nitrogen, and together with nitrogen it could be even more narcotic (Bennett 1993, Inert Gas Narcosis, the Physiology and Medicine of Diving, 4th edition)!

Dont believe that? Try IANTD:

http://www.iantd.co.uk/IANTD/pages/TA Kev Gurr.htm

PADI do(did?) teach oxygen was to be considered as narcotic as oxygen in their enriched air manual.

Given the latest thoughts about mechanisms for narcosis oxygen indeed should be as or more narcotic than nitrogen as well.