Nitrox vs Air

[emelotto]

I hate to use tables because till now I do just recreational dives as the name says, recreational means to enjoy a dive, not do guessing whether you will die or not if you do not use the tables. So I bought a computer which will do every calcs to me, even better than I could, because multilevel dives you will never know how will be.

So after more than a hundred dives you start to compare your computer with others and I find out that Suunto is almost always the more conservative one. If you are like me, always diving with a different buddy, you know this is a pain !!!

So I've made some exercises with the simulator and I guess with more less Nitrox 24% O2, my mosquito will be more less equal "liberal" computers using air.

Anyway, I would like to hear if somebody here already have done this comparisons or even used this trick. What our dive community think about that?

Since nobody analize the percentage of O2 inside tanks with gas, I could say that is not impossible to have more than 21% O2 (or less) in a tank. Is this 3% more is higly significative?

 

[teknitroxdiver]

Hmm. Interesting idea. I'll take your last question first, as it's the most straighforward to answer. If you're filling from a normal compressor, with no nitrogen-filtering equipment, and not adding any oxygen, you'll get 21% every time. You simply aren't going to somehow build up an extra 3% of O2.

As for setting it on 24%, wellllllllll.....if you've explored this a lot and find it to be a safe adjustment to make, I suppose it might not hurt you. However, keep in mind that the algorithms are designed to work best when used as intended. If you're really needing an extra few minutes, switch to another computer. Personally, I wouldn't trust 'more or less' for dives.

I dive a Tusa computer which is somewhat conservative. On a 140' wall dive, I needed 1 more minute of NDL to stay with everyone else, so I allowed the computer to go into deco mode (requiring 1 minute at 10 feet, no biggie). This stop cleared before I even made it to the top of the wall at 70'. Now, I would not make a practice of this, and sure wouldn't do it if I wasn't comfortable with what my computer was telling me compared to what the tables and my buddie's computers were saying, but in this case I thought it safe enough and went for it.

I'd say no, don't do it. Just take the couple of minute loss, it's no big deal really. If it IS a problem, get a more liberal computer (Aeris, Oceanic, Cochran, etc)

 

[in_cavediver]

I hate to use tables because till now I do just recreational dives as the name says, recreational means to enjoy a dive, not do guessing whether you will die or not if you do not use the tables. So I bought a computer which will do every calcs to me, even better than I could, because multilevel dives you will never know how will be.

So after more than a hundred dives you start to compare your computer with others and I find out that Suunto is almost always the more conservative one. If you are like me, always diving with a different buddy, you know this is a pain !!!

So I've made some exercises with the simulator and I guess with more less Nitrox 24% O2, my mosquito will be more less equal "liberal" computers using air.

Anyway, I would like to hear if somebody here already have done this comparisons or even used this trick. What our dive community think about that?

Since nobody analize the percentage of O2 inside tanks with gas, I could say that is not impossible to have more than 21% O2 (or less) in a tank. Is this 3% more is higly significative?

There is a much easier answer. Simply take the nitrox class and extend your bottom times with it. As for the dive times models allow, remember this, NO model can truly account for the nitrogen dissolved in YOUR body. They all use math to guess what in your body based on time/depth/mix information. I personally know of a diver who has been bent twice while diving within the limits of his 'liberal' computer.

Mike

 

[DA Aquamaster]

If you are not going to go all that deep, just go with a standard mix like Nitrox 1 (32%) and don't worry about a custom mix like 24%.

It would allow you 110 ft at a PPO2 of 1.4 and 130 ft at a PPO2 of 1.6 (although a PPO2 of 1.6 is not recommended under most current agency standards for use during the working portion of the dive)

I do use 25% on deeper dives to 150 ft, but mostly because it's readily and cheaply available from topping off used tanks (700psi) of 36%. The difference is not all that great compared to air but is significant on deeper and longer deco dives.

I would not set my computer for 24% and then dive air though to trick it into being a little more liberal - that would be asking for trouble and you would basically be turning yourself into a test diver on every dive.

 

[Don Burke]

I hate to use tables because till now I do just recreational dives as the name says, recreational means to enjoy a dive, not do guessing whether you will die or not if you do not use the tables. So I bought a computer which will do every calcs to me, even better than I could, because multilevel dives you will never know how will be.

So after more than a hundred dives you start to compare your computer with others and I find out that Suunto is almost always the more conservative one. If you are like me, always diving with a different buddy, you know this is a pain !!!

So I've made some exercises with the simulator and I guess with more less Nitrox 24% O2, my mosquito will be more less equal "liberal" computers using air.

Anyway, I would like to hear if somebody here already have done this comparisons or even used this trick. What our dive community think about that?

Since nobody analize the percentage of O2 inside tanks with gas, I could say that is not impossible to have more than 21% O2 (or less) in a tank. Is this 3% more is higly significative?

I really doubt you will find air tanks at less than 20.5 or more than 21.5. Maybe a Nitrox tank could sneak in on you, but that would be rare.

I would not lie to my computer. It would result in some interesting testimony in court if anything happened. Life insurance, dive insurance, and medical insurance companies like to jump on irregularities.

If matching time is important, get the same computer your buddys are diving with.

With several people to match, getting one a bit less conservative would seem to be the way to go.

 

[DandyDon]

Wow, this is a new one, but I can see it. Not the first diver to buy a "safer" conservative computer, then gripe at losing dive time. I'd be afraid of trying to trick the computer, tho. Oceanic computers are very reasonably priced, every bit as conservative as the Padi table (the only ones I've trained on so far), user friendly if you actually read the manual, and a better answer I think.

I personally know of a diver who has been bent twice while diving within the limits of his 'liberal' computer.

I know one here, and some people are more likely to get hit even within popularly accepted NDL limits, but - I wonder how many understand and accept that the Oceanic computers are designed to be safe if you leave the water in the Green - Not the Yellow or Caution Zone. I wonder if they convince themselves they should be okay as long as not Red...?

 

[Captain CaveMan]

I got a sunnto and it is a little conserative but 1-3 min thats nothing. if your doing rec diving you should not be diving close or over the limmit anyways. ENJOY THE DIVE-you said it your self

 

[jonnythan]

Save yourself the expense and hassle of Nitrox and get yourself a new computer.

 

[The Kraken]

Simple solution, why don't both you and your buddy dive the tables? They're the same for EVERYONE ! ! ! !

the K

 

[dkktsunami]

Trying to "outsmart" your computer is not a good idea.