Diving 32% Nitrox with "Air" Algorithms

[Blackcrusader]

Set it right, then don’t ride the NDL.

If OP is using 32% gas on a 21% setting then no riding of actual NDL will be done

 

[SysGreg]

The other issue is you are not tracing you oxygen load. O2 takes longer to out gas. If you are doing multiple dive and deep, you might have consider your O2 load and oxygen oxcity.

I agree, there is no CNS or OTU tracking when the dive computer is not set to proper gas mix. That could created issues on repetitive dives over several days.

By setting computer to air you rather want to stay on safe side of Nitrogen forgetting about Oxygen toxicity. There is nothing wrong with having proper gas in the computer and adjust Conservatism to be on safe side. That would be the best approach.

 

[bradlw]

a lot of this "lying to the computer" seems to be based on having good data and full picture
but
seems to me that this all presupposes that what the computers do with this data is all somehow perfect.

Personally I agree with the idea though of entering the correct gasses, adjusting it to a more conservative PO2 limit if you want, and not diving to the calculated limits if that's what you want.....

But I don't see that as really a whole lot of difference to the original proposal in many ways. Either method is just adding safety factor to a whole bunch of estimated, extrapolated, and calculated values.

 

[stepfen]

I know people that do the opposite (set their Suuntos to 23-25% while diving on air to get comparable NDLs to other DC!!!). Compared to that, what the OP is discussing is nothing really serious, but still, why not follow other well established techniques (stay away from ndl, longer ss, slower final ascents etc)?

 

[rhwestfall]

.....use tables and a timer and a depth gauge....

 

[NW Dive Dawg]

Thanks for all the responses. I guess my thinking has been that leaving our computers set to air, and staying above the MOD for 32, was really just another means of having my computer set to very conservative. But after a better understanding from all of these responses here, we'll be setting our computers conservatively to the gas we are actually diving.. We will however be keeping our personally agreed MOD for 32% at 100ft.....

One more question.... now that we're "old" most of our tropical trips are to Bonaire and LCBR as the diving in those areas is not too high on the difficulty scale. When on Bonaire we buy our shore diving package from Buddies because we like their drive through self serve tank farm and like to have authorized access to their dock. We like LCBR for the easy "valet" style boat diving. I think both of these outfits bank their Nitrox and have found that the O2 percentages are usually within .5 to 1 % of 32. And when it's not 32, it's usually a bit under rather than over. We always analyse to confirm. My question is, with these types of small percentage variances, do most folks just leave their computers set for 32........or do you re-adjust for the exact O2 percentage for each tank after analysing. Thanks.

 

[ChuckP]

If you do some dive planning using software, you'll notice there is mismal difference in the 31-33% range. If I constanantly get low 31% tanks, then I would make the effort to change it but a one off tank, nah....

Tanks here are +/- .5 in general and that is including the error of the meters...........

 

[Angelo Farina]

I already expressed my opinion on this point, but I see that it is not easily adopted by others.
I consider Nitrox a partially technical mixture, which provides some advantages but also increases some risks.
I equate it to a medical drug: good for getting some health benefits, but always associated to their inherent risks.
If possible I would avoid hyper-oxygenated mixtures as much as possible, particularly for dive profiles where the risk of decompression sickness is already very remote, as the NDL is far away.
If there is no benefit due to being already very far from NDL, while getting the many risks associated with Nitrox, for no benefits?
Oxygen is toxic and causes inflammation, cells are stressed and the body is pushed towards an "high metabolism" mode. Nothing of this is natural, nor healthy.
It can be useful as a therapy for some diseases, but, as any other medically relevant actions, I would avoid it, if not suggested by a medical doctor.
So, in the case of the OP, I would simply suggest to dive air, and to stay far away from NDL limits. Very simple...

 

[Robert H. Diver]

I already expressed my opinion on this point, but I see that it is not easily adopted by others.
I consider Nitrox a partially technical mixture, which provides some advantages but also increases some risks.
I equate it to a medical drug: good for getting some health benefits, but always associated to their inherent risks.
If possible I would avoid hyper-oxygenated mixtures as much as possible, particularly for dive profiles where the risk of NDL is already very remote, as the NDL is far away.
If there is no benefit due to being already very far from NDL, while getting the many risks associated with Nitrox, for no benefits?
Oxygen is toxic and causes inflammation, cells are stressed and the body is pushed towards an "high metabolism" mode. Nothing of this is natural, nor healthy.
It can be useful as a therapy for some diseases, but, as any other medically relevant actions, I would avoid it, if not suggested by a medical doctor.
So, in the case of the OP, I would simply suggest to dive air, and to stay far away from NDL limits. Very simple...

 

[tursiops]

Thanks for all the responses. I guess my thinking has been that leaving our computers set to air, and staying above the MOD for 32, was really just another means of having my computer set to very conservative. But after a better understanding from all of these responses here, we'll be setting our computers conservatively to the gas we are actually diving.. We will however be keeping our personally agreed MOD for 32% at 100ft.....

One more question.... now that we're "old" most of our tropical trips are to Bonaire and LCBR as the diving in those areas is not too high on the difficulty scale. When on Bonaire we buy our shore diving package from Buddies because we like their drive through self serve tank farm and like to have authorized access to their dock. We like LCBR for the easy "valet" style boat diving. I think both of these outfits bank their Nitrox and have found that the O2 percentages are usually within .5 to 1 % of 32. And when it's not 32, it's usually a bit under rather than over. We always analyse to confirm. My question is, with these types of small percentage variances, do most folks just leave their computers set for 32........or do you re-adjust for the exact O2 percentage for each tank after analysing. Thanks.

I leave my computer set on 31, and am happy diving up to 32.5 with that. I find the Buddy Dive blends to nearly always be under 32.