Nitrox the Wonder Gas

[skynscuba]

How deep have you gone with the chemical heaters and what percentage of nitrox are you using? Have you ever noticed that it gets too warm?

I use the hand ones like these http://www.heatmax.com/HotHands/hothands2.htm, and similar toe ones.

32 to 36 percent. I've been to about 95 feet with them on Nitrox, a bit deeper on air. I only put the heat packs at my toes and in the palms of my dry gloves. They seem to cook a bit better the EANx than with air, but still don't do a heck of a lot. I raise and lower my feet and hands to recirculate a fresh supply of air. I've heard BAD things about someone who used one of the larger heat packs, directly at the inflator valve inlet. Got way too hot.

 

[sharkattack]

If using nitrox removes that much more nitrogen from my breathing mix somewhat reducing my risk of a hit, I'm all for it. I have not used air on any dive in the last 7 years. Don't care how shallow the dive. For those concerned with getting narced, take a Triox course and throw in some He. Want more than 40% 02, take Advanced nitrox. Want to go deep? Trimix and Deco procedures. 3 reasons why people use Nitrox, Extend NDL, shorten surface interval, or added safety by using air tables/computer.

 

[PfcAJ]

It would seem to me that how you feel at the end of a dive is a function of how you decompress, not your breathing mixture. I think we are in an agreement that post dive fatigue is a form of subclinical DCS. Let's work from there.

If you dive nitrox, decompress well (saftey stops, deep stops, acent rate, surface deco, etc), its safe to say you will feel better (which is entirely subjective) than if you didn't decompress well. The same holds true with air diving.

Now, for a given dive within NDLs with nitrox (we'll say 32%), you'll be taking in less nitrogen than for the same dive with air. Make sense?

Diver A is a clone of Diver B. Diver A and Diver B do the exact same dive, same deco...but Diver A is on 32% but Diver B is on air. From this, we can assume that Diver A will feel less fatigued than Diver B.

Diver B is experiencing the effects of that additional nitrogen that was absorbed during the dive in comparison with Diver A.

When I first started diving Nitrox, I didn't know about scubaboard or the "it makes you feel better" thing. I discovered it myself. Now, 5 years later, I can judge my decompression by how I feel at the end of the dive. Its a function of decompression relative to nitrogen absorbtion. Its subjective (Argon, anyone?), and dependant on many variables.

 

[Richesb]

Spend some time under water instead of at a computer and you will find the benifits of Nitrox as well as the limitations.
It is not a "magic potion" not advertised as such.
We dive almost daily, repetitive diving and would be crazy not to dive Nitrox with the advantages it supplies.
I think all of you who have a few dives under your weight belts would agree. I also see daily , people want to equate the cost in dollars with the value of Nitrox.
Very foolish - and not worth arguing

 

[skynscuba]

Now, for a given dive within NDLs with nitrox (we'll say 32%), you'll be taking in less nitrogen than for the same dive with air. Make sense?

Makes sense if you meant "within air NDLs" not the extended nitrox NDL.

The "common knowledge" doesn't seem to support a significant decrease in clinical DCS when using nitrox to air limits, but I like the extra margin I get in case a faster than ideal ascent becomes necessary or some such emergency. And of course to allow me to make 4 or 5 dives in a day when on vacation, by going past air NDLs. I'm not saying that you don't feel less tired. I don't have enough dives to compare small effects, and none of my nitrox dives have been strenuous or at the NDL for the mix I was using.

 

[Twiddles]

I was suprised because both myself and my wife were told by two different shops and 4 diffrent divering instructors (maybee more) that items 1-4 were indeed the benefits of using Nitrox. For everyones talk about the added NDL time and of course nobody is mentioning that if your diving to your NDL limit you still need the same amout of SI before you can continue as you do with air. Additionally nobody is saying a word about oxygen toxicity? Sure you have a slightly reduced chance of DCS when your odds of actually getting DCS are less than 1 in 36563 per http://www.scubaportal.net/diving/index.php?option=com_content&task=view&id=171 or 2 in 10,000 per DAN is the risk of ox tox greater than the reduction in risk of DCS??

I think at least for me and my wife there has been much more hype than fact where Nitrox is concerned. I am of course basing my opinion on this article which is truly an opinion of Dr. Bennett, I cant really fathom a reason why his opinion would be jaded against Nitrox. I can however see a very clear reason why shops and some instructors would tout it as a wonder gas. Clearly this has been done alot or the article would not make sense.

Now if you truly are a deco diver a tec diver and you have the skills, then obviously Nitrox has a place in reducing your deco stop time. For the rest of us wannabies it appears that its a pretty sticker on the side of our tanks.

Another article from Dr. Bennett

Although the overall risk of experiencing DCS while diving with either air or nitrox is still very small (a 0.05 percent risk with air and 0.12 percent for nitrox, using 1996 data), at the very least, nitrox still does not appear "safer" than air. In regard to fatalities between 1990-94 there were eight recreational deaths in divers breathing mixed gas: two in Œ94, three in Œ95, two in Œ96 and one in Œ97.

If we infer there are 2 million active recreational divers in the United States and approximately 90 deaths per year, this means a fatality rate of 0.005 percent. With nitrox taking an average of two out of 17,880 trained divers, then the percentage is a little higher at 0.01 percent.

 

[fisherdvm]

I use nitrox in the bedroom. Makes wife happier.

 

[MXGratefulDiver]

I was suprised because both myself and my wife were told by two different shops and 4 diffrent divering instructors (maybee more) that items 1-4 were indeed the benefits of using Nitrox. For everyones talk about the added NDL time and of course nobody is mentioning that if your diving to your NDL limit you still need the same amout of SI before you can continue as you do with air. Additionally nobody is saying a word about oxygen toxicity? Sure you have a slightly reduced chance of DCS when your odds of actually getting DCS are less than 1 in 36563 per http://www.scubaportal.net/diving/index.php?option=com_content&task=view&id=171 or 2 in 10,000 per DAN is the risk of ox tox greater than the reduction in risk of DCS??

I think at least for me and my wife there has been much more hype than fact where Nitrox is concerned. I am of course basing my opinion on this article which is truly an opinion of Dr. Bennett, I cant really fathom a reason why his opinion would be jaded against Nitrox. I can however see a very clear reason why shops and some instructors would tout it as a wonder gas. Clearly this has been done alot or the article would not make sense.

Now if you truly are a deco diver a tec diver and you have the skills, then obviously Nitrox has a place in reducing your deco stop time. For the rest of us wannabies it appears that its a pretty sticker on the side of our tanks.

Another article from Dr. Bennett

Although the overall risk of experiencing DCS while diving with either air or nitrox is still very small (a 0.05 percent risk with air and 0.12 percent for nitrox, using 1996 data), at the very least, nitrox still does not appear "safer" than air. In regard to fatalities between 1990-94 there were eight recreational deaths in divers breathing mixed gas: two in Œ94, three in Œ95, two in Œ96 and one in Œ97.

If we infer there are 2 million active recreational divers in the United States and approximately 90 deaths per year, this means a fatality rate of 0.005 percent. With nitrox taking an average of two out of 17,880 trained divers, then the percentage is a little higher at 0.01 percent.

Sounds to me like you're finding some really poor instructors down there ... surely there must be come better ones in Sacramento. Certainly no reputable instructor would perpetrate the myths you started this thread with ... I can tell you that the NAUI student (and teaching) materials point out that those are fallacies, fairly early in the presentation. I suspect PADI's do too.

Ox tox is a very real concern, but one that's easily avoided by simply maintaining conservative PPO2 limits and not exceeding your maximum operating depth. Even for the occasional recreational diver, this does not impose a significant amount of self-discipline ... you simply have to plan your dive based on your mix, and then dive your plan. If planned properly, there is always some "wiggle room" for unexpected situations that may require a brief interlude at a somewhat deeper depth (+15-20 feet or so) without significant risk.

The deaths that Dr. Bennett points out indicate that ox tox has a higher risk of fatality than does DCS.

All of these concerns were hashed out at great length in the early '90's ... when nitrox was just coming into its own as a breathing gas for recreational divers.

... Bob (Grateful Diver)

 

[Somethin-Fishey]

Still researching for safety stops and happened across this article, was more than a bit surprised by the statements made. http://www.scubadiving.com/article4545

What Nitrox Won't Do
Claim #3
Less fatigue. "Those long and tiring drives returning from a day of diving are over!" enthuses one dive shop's web site on the benefits of diving on nitrox. Is it really the "feel good" gas? The theory here is that the work of offgassing nitrogen is a major cause of diving fatigue, so less of it should leave you less tired. Many nitrox divers swear it's true, but Bennett cites a blinded study that proved otherwise. Using unmarked tanks, one group of divers was given nitrox, another was given air, and both were asked later how they felt. "There was no difference," says Bennett. "It's a placebo effect."

Placebo, maybe, but I can't imagine feeling good doing the repetitive dives on air....especially staying down at 100ishft for 64 minutes...the deco time etc would be horrible..... When we dive it is work....Speargun is cocked and we are hunting...kicking hard, wrestling Bugs etc.... The few times I have dove on air, I feel like someone hit me with a stick...not so with Nitrox. Maybe it is in my head, but my legs and calfs tend to agree with my head.... I don't feel "Good" either way, just less beaten.

Now, if you give divers unmarked air and tell them to go to 60ft, sit there for 20 minutes and surface...I can't see much difference...

 

[cummings66]

Okay, I'm making my predictions now...
1) Those who use Nitrox will (having paid for the class, the computer and the tank) swear by how much it helps.

I'm nitrox certified and I agree with the article 100%. It is no surprise at all, in fact it should be common knowledge. Every point IMO is right on track, and jives with my diving of it. I dive it all the time so I know what works for me.