Nitrox diving and your computer settings

[ianr33]

Exactly. I was diving in Cozumel with a friend and we found this out the hard way. If you're diving nitrox at all, you must use 21% nitrox instead of air on a Suunto.

Wonder why Suunto dont program their computers to do the O2 calculations in the background when set to air?

 

[promocop]

Why would you mess around and 'trick' the computer? Do we not believe that the 'experts' that wrote these programs dont know what they are doing? I've got a SOL, I and I just set it to the mix I'm using and let it do its thang. I'ts plenty conservative anyway.

 

[MMM]

All 3 of my Oceanics and my Aeris Manta have Air and 21....I was ready the manual on the Oceanic today and the reason they give the option of both 21 and Air is, if you have a dive on Notrix say 32% then your next dive is Air...the computer will not alloow you to set it to Air. It will allow you to set it to 21% for the O2 tracking.

Yes, same with my 3 computers (Suunto, TUSA and Gallileo Sol. Who wants to be switching between air and nitrox anyway AND adjusting mix numbers. Just adjust the latter.

 

[Walter]

Why would you mess around and 'trick' the computer?

Who mentioned tricking the computer?

 

[GrandpaScuba]

Hi, Just wondering why you would not want to dive with your computer set on nitrox with a 21% mixture, while diving with a regular air mixture?
Thanks

Some people do. Especially if they are switching between air and nitrox on different dives.

 

[Rhone Man]

Wonder why Suunto dont program their computers to do the O2 calculations in the background when set to air?

The main problem with Suuntos is that you cannot do gas switches in air mode. Hence I set mine for EANx21.

 

[scubadiver888]

I am using a Suunto Cobra that will do the same thing. If I have my first dive of say 32% and my next dive is air, the computer will only allow me to set it at 21% in the nitrox setting. I started the thread because I recently read an article about setting your computer to 21% in the nitrox mode and why you should not do this and I can not find the article. It is driving me nuts. It was in either Sport Diver or Scuba or Dive Training or Under Current. Perhaps someone read the same aritcle.

I read an article recent which talked about why you should not set your computer to Air when you were diving with an enriched air nitrogen mixture.

Apparently, some people advocate setting the computer to Air or 21% Oxygen when diving with say EAN32. The advantage is that the nitrogen levels will be calculated assuming ~79% nitrogen. Because the nitrogen levels are actually much lower (~68%), it will be more conservative in calculating nitrogen loading.

The article pointed out that you run the risk of oxygen toxicity by doing this. The benefits of reduced nitrogen loading do not justify the increased risk of oxygen toxicity. Maybe you are mistakenly thinking about that article.

 

[parzdiver]

My computer (Cochran) doesn't have an "air" setting, you can only set the fraction of O2. So for diving air it is 21.0. My particular configuration allows setting up to 40.0 in increments of .1%.

 

[Blackwood]

Wonder why Suunto dont program their computers to do the O2 calculations in the background when set to air?

maybe battery life? I don't know. But it does seem kinda stupid.

 

[Rhone Man]

maybe battery life? I don't know. But it does seem kinda stupid.

Not to hijack the thread, but I always remember being struck by a comment that John Chatterton said during a seminar. He was saying "in the old days" people used to dive air to 230 feet and deeper, pushing the ppO2 of air above 1.6 ATA, but he could never recall anyone ever toxing on air.

Hardly a scientific survey, but I remembered wondering at the time (given how little we know about CNS toxicity) if there was something in that - it was not purely a feature of partial pressure, there was some kind of accelerated risk curve for richer mixes.