Pros and Cons of Nitrox: What are they?

[Hemlon]

if anybody does that, they deserve to be smacked around.

but then again, there are some types of people who will look upon anything as
an excuse to look down on others. i try to avoid them at all costs.

Thanks, H2Andy! It was nice of you to say that. (Sometimes I forget!)

:11ztongue

 

[MikeFerrara]

The only advantage of Nitrox is a longer bottom time. Contrary to what some dive shops tell you Nitrox is not proven to be safer than air. Although it reduced the chances of DCS somewhat, it also introduces other risks (oxygen toxicity being the main one) and the overall accident rate of Nitrox divers is significantly higher than that of air divers. This does not necessarily mean that Nitrox would be unsafer either: Nitrox is probably more often used by (tec) divers who do higher risk dives.

I watch the accident reports pretty close and I haven't seen that accident rates are higher in nitrox divers. What kind of accidents? Can you point me to some documentation?

IMO you should use Nitrox only if it gives you significant gains in actual bottom time (increasing your NDL from 45 to 65 minutes is meaningless if you have only 40 minutes of gas!) and it fits your diving depths.

I couldn't disagree more strongly. Especially over a multi-day dive trip the difference in nitrogen loading can make a lot of difference. It's not always about getting more bottom time it's about soaking up less nitrogen. I can dive as long as I want regardless of the gas I use but less nitrogen is better.

Regarding the interchangeability of regs, hoses and SPGs between air and Nitrox, this has been discussed heatedly in several occasions. Virtually all manufacturers will warn against it.

Not true. Most manufacturers make no such recommendation for FO2 below 40%. Few require their products to be O2 serviced for mixes below 40%. I'm a dealer and authorized to service for several manufacturers and I haven't seen such a warning yet. The need for dedicated regs for recreational mixes is a total myth.

This includes of course some CYA, but...there still must be a reason for CYA. At the same time there are quite a few divers that do it. The problem is that it is difficult to measure the effects: it is unlikely that your reg will explode, but repeated combustion could cause significant wear on your equipment.

How is switching back and forth between air and nitrox going to cause repeated combustion? If the nitrox was mixed by some method other than PP blending there isn't any reason to believe that the air that was used to blend meets mod grade E standards. Switching back and forth doesn't mean anything at all.

On the other hand even if you wish to maintain the O2 servicability of a clean and O2 compatable piece of equipment you could still use mod grade e air without trouble. The only risk would be contaminants from reg grade E air or EANX blended using regular grade E air.

 

[SamDiver14]

I think that both sides of the Nitrox argument have a single point. No one knows what will absolutely prevent accidents. Some people feel that Nitrox gives them a mathmatical advantage and thus a higher degree of safety. When there is no way to absolutely prevent DCS why not excercise as much caution as possible? It is important to note that there is no guarantee that nitrox will prevent an accident and the extra margin of safety is no excuse to push the NDL limits. DCS is accepted to be caused by excess nitrogen in the body. If there is less nitrogen there should be less risk. There are more important risks though, dehydration, physical fitness, age, and previous injury to name a few. Our sport is one of technology and equipment. I feel that Nitrox gives me enough of an advantage to make it worthwhile. In this sport to refuse to learn and change as science improves our knowledge of dive physics is a dangerous position to take.

 

[Hemlon]

In the limited diving I have done so far, I'm not sure that I want to stay down any longer than the tables allow.

Usually by that time, I am tired and thirsty!

 

[gj62]

In the limited diving I have done so far, I'm not sure that I want to stay down any longer than the tables allow.

Usually by that time, I am tired and thirsty!

As you acclimate, you will - especially as you dive deeper. Also, Nitrox is something that greatly benefits you on days when you do multiple dives - or dive vacations where you dive multiple times on successive days - it really helps to reduce the N2 buildup - something that is important even for people who tend to not push the NDLs.

 

[Cudabait]

Yikes, If I have to have a Nitrox-dedicated reg, that's gonna' be expensive! (I just bought my first reg last month!)

Hemlon,

I couldn't tell by your profile if you are nitrox certified. Anyway, don't sweat it. That new reg you just bought will do just fine for mixes up to 40 per cent O2. Most of the time anything other than 32 or 36 will have to be mixed to order anyway.

Regards,

 

[5615mike]

I think that both sides of the Nitrox argument have a single point. No one knows what will absolutely prevent accidents. Some people feel that Nitrox gives them a mathmatical advantage and thus a higher degree of safety. When there is no way to absolutely prevent DCS why not excercise as much caution as possible? It is important to note that there is no guarantee that nitrox will prevent an accident and the extra margin of safety is no excuse to push the NDL limits. DCS is accepted to be caused by excess nitrogen in the body. If there is less nitrogen there should be less risk. There are more important risks though, dehydration, physical fitness, age, and previous injury to name a few. Our sport is one of technology and equipment. I feel that Nitrox gives me enough of an advantage to make it worthwhile. In this sport to refuse to learn and change as science improves our knowledge of dive physics is a dangerous position to take.

You keep using the terminology of "accident". Accident and DCS are not synonomous. DCS is no accident. It's a sickness to the body in very elementary terms but no "Accident". No, EANx is not going to prevent an "accident". It's not going to prevent DCS. It WILL, as Mike outlined so well in an earlier thread, if your diving multi dives/days, effect nitrogen loading. Less Nitrogen is ALWAYS BETTER.......PERIOD. Can't agrue that fact.

My point is be careful of your terminology. You know what you meant but new divers may get the wrong idea.

 

[ScubaRon]

I watch the accident reports pretty close and I haven't seen that accident rates are higher in nitrox divers. What kind of accidents? Can you point me to some documentation?

I couldn't disagree more strongly. Especially over a multi-day dive trip the difference in nitrogen loading can make a lot of difference. It's not always about getting more bottom time it's about soaking up less nitrogen. I can dive as long as I want regardless of the gas I use but less nitrogen is better.

Not true. Most manufacturers make no such recommendation for FO2 below 40%. Few require their products to be O2 serviced for mixes below 40%. I'm a dealer and authorized to service for several manufacturers and I haven't seen such a warning yet. The need for dedicated regs for recreational mixes is a total myth.

How is switching back and forth between air and nitrox going to cause repeated combustion? If the nitrox was mixed by some method other than PP blending there isn't any reason to believe that the air that was used to blend meets mod grade E standards. Switching back and forth doesn't mean anything at all.

On the other hand even if you wish to maintain the O2 servicability of a clean and O2 compatable piece of equipment you could still use mod grade e air without trouble. The only risk would be contaminants from reg grade E air or EANX blended using regular grade E air.

Mike,
I really didn't want to restart this discussion, but since you asked:

1. The accident rates are from the DAN 2004 report, but you'll need to make some calculations (number of nitrox accidents/number of nitrox users). I realize that this is not the primary intent of these numbers and that there are other factors involved in this. I personally believe that Nitrox, when used properly is as safe as air. What I do not believe (at least not until I see proof) is that it is safer than air, which I hear some people claim.

2. I agree with you on the benefit of nitrox in multiday repetitive diving, but considered this as part of the increased bottom time.

3. From the Atomic Aquatics user manual:
At time of purchase, you must decide if this regulator is to be used with EAN or standard compressed air. If you desire to use EAN, this product must be dedicated for EAN only and identified as such. Do not switch between EAN and standard compressed air, as compressed air may contain traces of hydrocarbons which could contaminate your regulator system with potentially flammable residues incompatible with EAN. If you use or test this regulator with compressed air, it must be re-cleaned before EAN use.
From the Aqualung user manual:
...if a regulator has had use with Grade E breathing air, it should receive a standard overhaul including ultrasonic cleaning with a detergent solution that removes hydrocarbons, prior to being put back into nitrox service.
Mares and others have similar statements.

4. Of course switching between O2 compatible air (which I presume you mean with "mod Grade E"...) and nitrox is no problem. But most standard air is Grade E, which is not O2 compatible. So repeated switching means repeated introduction of hydrocarbons, ergo repeated combustion. The question is how this impacts your reg in the long term and that is where facts lack and opinions differ.

 

[Scubaguy62]

Mares and others have similar statements.

Actually Ron, Mares' statement reads "Mares regulators and octopus are designed and intended for use only with clean, compressed atmospheric air." "Do not use this equipment with any other gas or enriched air."

The reason for that is because Mares markets a nitrox version of their regulators, and this statement is intended to incite the owner to purchase the nitrox dedicated regulators. I have a V16 epos and an MR12 Axis, both of which are in their standard configuration, and I use nitrox exclusively with these regulators without any problems.

Don't know much about aqualung (other than the Titan LX is certified from the manufacturer for mixes of up to 40%), or atomics, but it seems both manufacturers mimic Mares.

Rick

 

[mech]

I just (and I mean just) passed my nitrox class.
I'm not sure that this has been addressed yet but I've been told numerous times that there is a reduction in being fatigued, as in being less tired after multiple dives or multiple days of diving due to less off gassing.
I live a good 1 1/2 hour drive from the ocean so when I go diving 3-4 tanks is not uncommon.On vacation I'll dive into the night (because I'm a pig).
Lately over half my dives have been around 35-40ft working on fundamental (skills ascents and decents on particular).
I'm thinking that a reduction in nitrogen will help me not be so wiped out at the end of the day.
Is my thinking on track ?
Also I dive wet in CA.