How does Nitrox work?

[Kevrumbo]

Pardon the editing above but let me ask this, If Nitrox was the same cost as air and the dives were well within MOD limits would you use it?

Yes . . .in Chuuk, the Truk Odyssey offers free-of-charge Ean30 for all certified Nitrox Divers, and use of double AL80's for those Tech Certified; the only dives I didn't use it were on the Hoki Maru at 43m; Nippo Maru 47m; and the San Francisco Maru at 51m (Ean30 MOD is 43m @ PO2 1.6).

Otherwise, on all week long liveaboards (like the Skydancer in Galapagos in which I just returned from yesterday! ), I save money and avoid the hassle/herd mentality of analyzing & logging in before every dive --and just use air mix.

 

[MaxBottomtime]

Pardon the editing above but let me ask this, If Nitrox was the same cost as air and the dives were well within MOD limits would you use it?

In most cases I would use air. If I'm making a dive involving mixed gasses and extended deco obligations I use 50% Nitrox above 70 feet and 100% O2 above 20 feet. If I make a dive with little to no deco in less than 150 feet I would use air. The only dives I can see using Nitrox full time are working dives, such as net removal. I want to get more bottom time with less deco obligation in that case. For other dives the ndl of air doesn't bother me. If I get a few minutes of deco, I just consider it the shallow portion of the dive.

 

[DandyDon]

MaxB is probly much better with his air consumption than I. I don't mind going into Deco (got the card) but toting enough gas to work that off becomes my next question.

In my limited but nonetheless observed experiences...

If I dive Nitrox and keep my Oceanic dive puter in the yellow, I can reduce that to green with deep and safety stops - and I like to always leave the water in the green.

If I get my puter into the red deco zone, I have never been able to get it back to green on that dive breathing my back gas - air or nitrox that I recall. Leaving the water in yellow carries forward to subsequent dives to an extent as my body is carrying the additional nitrogen load, theoretically - which is what we all use: theory and anecdotal evidence.​

If Nitrox was $3/tank on Coz like it is in some places, I'd use it on virtually all dives there. When I first got my card, I did use it on virtually all there, but soon after learned I was overdoing that. For my air consumption even on 80s on those multi level dives, tho - 4 dives in a day pushes me very close to NDL, or over.

 

[offthewall1]

If Nitrox was $3/tank on Coz like it is in some places, I'd use it on virtually all dives there. When I first got my card, I did use it on virtually all there, but soon after learned I was overdoing that. For my air consumption even on 80s on those multi level dives, tho - 4 dives in a day pushes me very close to NDL, or over.

Finally, it sounds like Don is agreeing with me : )

 

[offthewall1]

Pardon the editing above but let me ask this, If Nitrox was the same cost as air and the dives were well within MOD limits would you use it?

Yes & No... usually no.

If I were diving where Nitrox made a significant impact on the diving I was doing... like say I decided to do some hardcore (multiple dives over multiple days) mid-range diving with limited time for surface intervals... then yes, I would dive Nitrox. I've stated numerous times it has it's place.... but not for the average recreational diver. The anecdotal marginal amount of safety everyone is talking about is barely a reality for someone doing one or two dives at the local quarry or even a 3 day trip to Cozumel doing 2 dives a day.

In general... my answer is NO... but there are exceptions to every rule

 

[Diver0001]

Frankly guys, You're all giving the dive op that did this more credit than they deserve

For one thing, it's stupid if not out right illegal in some areas for an op to give an unqualified diver Nitrox.

Secondly, the client asked for air and didn't get it. If you asked for Nitrox and the operator gave you air then you'd all be moaning about how terrible this operator was for not listening.

If I were offthewall1 I'd be getting irritated with you guys for acting to nonchalant about this. Filling a tank with anything other than what the diver asked for is bad business, it's bad policy, it's potentially dangerous and it's stupid.

I'm especially surprised to hear one or two people who I hold in very high regard saying that they don't see the problem.

R..

 

[Diver0001]

BTW, Offthewall1, I wouldn't use this example to teach your divers about Nitrox. Instead I would use it as a clear example of unethical practices by dive shops and that there will be times that they will have to say NO and walk away instead of diving with what a shop gives them. Be it gear, gas or whatever.

Use it as a wake up call to get your students to think about the services being provided to them and you will have given them a better tool than knowledge of Nitrox alone...

R..

 

[MaxBottomtime]

MaxB is probly much better with his air consumption than I. I don't mind going into Deco (got the card) but toting enough gas to work that off becomes my next question.

In my limited but nonetheless observed experiences...

If I dive Nitrox and keep my Oceanic dive puter in the yellow, I can reduce that to green with deep and safety stops - and I like to always leave the water in the green.

If I get my puter into the red deco zone, I have never been able to get it back to green on that dive breathing my back gas - air or nitrox that I recall. Leaving the water in yellow carries forward to subsequent dives to an extent as my body is carrying the additional nitrogen load, theoretically - which is what we all use: theory and anecdotal evidence.​

If Nitrox was $3/tank on Coz like it is in some places, I'd use it on virtually all dives there. When I first got my card, I did use it on virtually all there, but soon after learned I was overdoing that. For my air consumption even on 80s on those multi level dives, tho - 4 dives in a day pushes me very close to NDL, or over.

I make occasional tech dives, but for the most part I'm a recreational diver. I have used nitrox for some recreational dives, but only a few. In twenty years and nearly 1500 dives, I've never made more than three dives in a day. 95% of the time I make one dive. I have nothing against nitrox use, it just doesn't make any difference in the diving I do. I'd rather save the money and put it toward my next boat.

 

[Puffer Fish]

AIR

I've dove as many as 22 dives in one week to depths between 50 - 150 feet... group dives where everyone else dove Nitrox... Why did I dive air?

Well that would explain a lot...I would be doing maybe 30 or more dives..

There are a few places where shallow water makes nitrox a waste of money...but most places, that is not the case.

This last weekend...on Sat... first dive... 82 ft for 38 (rounded up the 30 seconds) minutes bottom time...next dive...65 ft for 47 minutes bottom time... with a surface interval of just over an hour. Those would both be deco dives on air.

Next day..83 ft for 33 minutes bottom time...next dive 69 ft for 37 minutes bottom time.. with a 55 minute surface interval.

(obviously, all those dives total time was a lot longer - my average total time is just over 50 minutes per dive).

All the second dives were called so that the boat could get back to do an afternoon run.

Nitrox allow me to enter the water first.. have all the air divers use up their air or run into deco issues.. and then exit...and that short surface interval helps the boat get back on time..

Air works for those dives only if one uses up their air or is happy with 25 minute dives...and at the cost of a trip...having an extra 60 to 75% more bottom time would seem like a deal

 

[Diver0001]

It does of course in certain circumstances reduce nitrogen loading significantly enough that it may be considered a benefit. Multiple dives on multiple days. It may also shorten surface intervals for impatient individuals who feel they need to jump back in the water almost immediately after getting out.

I'm getting into this thread late so I'm just going to pretend like I belong here...

For local diving I dive air most of the time because I get it free. On a yearly basis the difference in price between diving air and diving nitrox in my case is probably about 500-odd euros (around $700) plus the hassle of having to drive a lot further for Nitrox fills.

When I'm diving wrecks I use nitrox because I have to pay a lot for the boat ride and I make longish dives that require 20-odd minute ascents even using 32% on teh bottom and 50% for the trip back.

If I had to grind that out on air the people on the boat would hate me by the time I surfaced.

R..