whats the deal with nitrox?

[Doc Intrepid]

scubapolly, why do you think Nitrox is safer? Do you have any supporting documents? Although Nitrox is most certainly a great gas to dive with I'd be careful saying it's more safe and suggesting that someone dive Nitrox with an air computer. I haven't found any PROOF that Nitrox is safer. There are simply too many other contributing factors to DCS/DCI. I think that everyone should dive some form of Nitrox as soon as possible and every chance they can, but only on dives where it can be of benefit, dives between 60-130 fsw +/-. The single most prevelant benefit of Nitrox is longer bottom times and/or shorter surface intervals. Safer maybe, less tired after diving, some say, but using Nitrox with an air computer is a waste of time (bottom time).

Not piling on you, Mike, just a couple cites in response to your comments.

Rutkowski and Somers (IANTD, 2000) discuss Nitrox (EAN) as "safer" in their textbooks, defining "safer" as a reduced exposure to N2, relative to DCS. They also state that diving EAN on air tables provides greater "conservatism" (ibid).

Gilliam (2001) also discusses EAN as "safer", using the same definition and context.

Both note that reduced exposure to N2 comes with a price - the increased exposure to O2! In that sense there is, to some extent, a 'trade-off' - e.g. it isn't safer if you don't analyze your gas, watch O2, and pay attention to MOD!

I agree with you that many (other) factors impact a diver's predisposition to DCS. Also agree that the physiological mechanisms involving on-gassing and off-gassing from different tissue groups are imperfectly understood.

Given what IS known, however, and given that physiological mechanisms often (but not always) degrade to varying degrees in older divers, the statement "diving with EAN is likely safer for older divers" seems to be well founded (using that definition and context for the word "safer" - and assuming that the diver pays attention to O2 exposure and MOD). Moreover, using EAN while diving air table exposures undeniably reduces exposure to N2 (from the exposure provided by air). In this specific sense, then, EAN therefore adds an inherent degree of conservatism for divers who desire to reduce their risk of DCS.

 

[rjchandler]

1/2 0f 0 = 0. It may be safer in amounts not important enough to measure.

 

[MXGratefulDiver]

considering your profile, the commentary is to say the least, disappointing
As I stated in my previous reply, generalities like yours dont provide any info just dictate. The 40yr old thing is lame and could be said about females due to general percent of body composition, or just anyone with over 5percent body fat,and not even go to PFO etc.
Nitrox is a tool, it equates to equivalent air depth, which is something for the individual diver to evaluate for risk vs benefit. The same goes for helium in the mix, max ppO2, deepstops, deco gasses, safety stops and the list goes on. A diver needs to research what could be advantageous to his or her own situation and not be given meaningless rules or suggestions based on to say the least a questionable opinion

Please try to make your point without the harsh language ... and keep in mind that this forum is directed toward new divers, not people who are likely to understand what terms like "max ppO2, deepstops, and deco gasses" mean. If you're going to introduce those terms into the discussion, perhaps you should consider explaining how they pertain to the discussion.

Play nice ... and keep in mind that the new divers asking questions in here are looking for information, not arguments ...

Thanks ...

... Bob (Grateful Diver)

 

[Doc Intrepid]

1/2 0f 0 = 0. It may be safer in amounts not important enough to measure.

Joe,

For a single dive, perhaps not. Or two.

But partial pressure exposures are cumulative.

Consider a liveaboard dive trip. Making 4 or 5 dives per day/night for 6 or 7 days in a row. Under different circumstances, the difference may be more than academic.

 

[Michael Schlink]

No one (and certainly not me) is going to argue that less Nitrogen loading is better than more. And diving "Nitrox" on week long liveaboards is the only way to go for me, however I still maintain that there is little evidence that Nitrox is creating a lower incidence of DCS/DCI. If it is please let me know where I can find this FACTUAL evidence so I can pass it on to my students. Polly raised my eyebrows when she suggested that divers over 40 should use Nitrox to help prevent DCS/DCI. The question was unquote " why use nitrox" In my opinion the best, not the only, reason is it will yield longer bottom times in certain dives. Nitrox should be used with same respect as any gas, but diving Nitrox with an air computer is a waste of bottom time. Quote Brett and Rutkowski all you want, I want proof.

 

[MikeFerrara]

Michael is correct in what he's saying except that some of us don't decide what dive we're going to do based on our gas. I can stay down as long as I want. So...given the dive that I want to do, I decide what gas is going to work best.

There might be enough variables that a small change in the amount of nitrogen absorbed in a population of divers might have a statistically insignificant effect compared to other variences in dive habits such as ascent rates or phisical conditioning. There may or may not be a correlatable difference in the DSC incedents.

The fact is tou that when it comes to predicting the out come of MY dive, I don't care about the population because I'm a sample of one. If I'm going to do a dive to x depth for y time the question becomes what's the best way to do it. If I breath less nitrogen my chances of a DCS hit is reduced as compared to using air on the same profile.

If I modify my decompression then the difference may be a wash.

So...what's the question? If I ask if introducing nitrox to the population will reduce the number of DCS cases I might have to go with Mike and say that there are factors that have a greater effect.

OTOH, if I ask if the addition of nitrox is going to reduce MY chances of DCS for the dive that I have planned...the answer is yes because in this case everything else is equal and only the gas changes.

 

[Michael Schlink]

As usual well said Mike. I agree completely. There are some places I dive, however, where I don't have the choices of gases that I prefer. I dive the same way you do, as I think alot of more experienced and/or "tech" divers do also.
I would like to throw this out without being accused of "trolling" or getting "flamed" etc., etc.
If Nitrox is indeed "safer" why isn't it the gas we start new divers out on. I have proposed that when training new divers that they be started on Nitrox right out of the gate. Tell them come h#*l or high water don't go below, say 110 with 32% and train them with proper gas planning and mgmt. Is this crazy or not-what do you think

 

[busraider1]

Nitrox is most beneficial between the depths of 40- 70 feet, where bottom time is greatly increased versus convential air.

 

[ChrisA]

I always encourage divers to get Nitrox certified as soon as possible, this is even more important for divers 40+.
I hope this answers your questions, let me know if it doesn't.

"40+" that's me. Why do you say that?

One other question: I would thnk that if you breath nitrox you'd
need less volume of gas to support the same level of activity. I would
think it would help with air cosumption but people tell me "no"

 

[Michael Schlink]

I read somewhere that Nitrox increases breathing efficiency by about 12-13%, don't remeber where, --who knows??!!!