21% Nitrox

[drk5036]

I think this is the big question. To the OP, you DO realize 21% nitrox is the same as air right? There’s nothing wrong with your log...

I don’t think calling it 21% nitrox is inaccurate. Calling it enriched air would be.

 

[EFX]

But a programming constraint is something that the programmers decided, for some reason, to incorporate into their program. It is not some immutable natural law but a human decision.

My question is why did they make this decision? If it is tracking PO2, why not simply continue tracking the PO2 while on air which is what is happening when you use 21% Nitrox?

Yes, the decision for preventing the switch from EAN to air is of course a human decision. What I meant was from a purely programming perspective there is no reason to make that decision based solely on the programming itself. In my spreadsheet the basic drivers for calculating oxygen accumulation are depth, ppO2, and time. The gas mix, air or nitrox, is irrelevant. Any difference in programming will make no difference in battery life. Since the display is a big user in power, dropping the O2 accumulation from the display would increase battery life provided some other data wasn't taking its place.

As to why did they make this decision. My guess is for two possible reasons: (1) switching to air the display drops the O2 accumulation reading, or (2) divers will pay more serious attention to the O2 "clock" when the DC is in nitrox mode.

Keep in mind that multiple dives can be made on nitrox that can bring the O2 accumulation close to 100%. Despite SI's, switching to air doesn't eliminate additional accumulation of O2, it simply slows it down relative to EAN. So, to make divers conscious of this the above two reasons are given.

 

[Belzelbub]

I realize that Nitrox 21% is air, hence the title of the thread.

When I want to say get a count of Nitrox dives the log is incorrect. I am an engineer, accuracy is important to me and calling an air dive as Nitrox 21% is inaccurate.

If accuracy is important, then you are incorrect to say it’s inaccurate. Calling an air dive as Nitrox 21% couldn’t be more accurate. Air is Nitrox. Calling it enriched air nitrox, or EAN21 wouldn’t be accurate because it’s not enriched, but air is Nitrox.

 

[tursiops]

I realize that Nitrox 21% is air, hence the title of the thread.

When I want to say get a count of Nitrox dives the log is incorrect. I am an engineer, accuracy is important to me and calling an air dive as Nitrox 21% is inaccurate.

With all due respect, that is just silly. I'm an engineer too....and what you say is just silly.
Count the number of 32% dives.....or >23% divers....what they are called is irrelevant.
Accuracy is indeed important.....and air is Nitrox, just a certain percentage.
Any why does it matter how many Nitrox dives you've had? they are ALL nitrox, just with varying percentages.
You are obsessed with this. Get over it.

 

[EFX]

Wait.....Maybe air is depleted EAN or could it be EHN (Enriched Hypoxic Nitrox). Naw, let's just call it normoxic nitrox.

 

[ThatDogDontHunt]

And this seems to present the question: why does a nitrox capable computer even have an "air" mode?

Is it merely because the marketing people at the manufacturer thought we are too stupid to set the mix to 21%?

On of my models of computers is air only. No issues. The other models are nitrox capable and allow you to set your mix. They do not have an "air" mode.

Is having an air mode popular?

 

[EFX]

I think it's a convenience for divers who are not nitrox certified or who do not know or understand O2%. With air there is no additional settings of O2% and max ppO2.

 

[EFX]

Yes, the decision for preventing the switch from EAN to air is of course a human decision. What I meant was from a purely programming perspective there is no reason to make that decision based solely on the programming itself. In my spreadsheet the basic drivers for calculating oxygen accumulation are depth, ppO2, and time. The gas mix, air or nitrox, is irrelevant. Any difference in programming will make no difference in battery life. Since the display is a big user in power, dropping the O2 accumulation from the display would increase battery life provided some other data wasn't taking its place.

In my original post above the last sentence used to read ".....would decrease battery life .....". I fixed it in the original post.

 

[Ontwreckdiver]

And this seems to present the question: why does a nitrox capable computer even have an "air" mode?

Is it merely because the marketing people at the manufacturer thought we are too stupid to set the mix to 21%?

On of my models of computers is air only. No issues. The other models are nitrox capable and allow you to set your mix. They do not have an "air" mode.

Is having an air mode popular?

My computer automatically reverts back to 21% after 2 hours.

 

[Wookie]

My computer automatically reverts back to 21% after 2 hours.

Which really sucks on a liveaboard, but better than reverting back to 79% N2 and 50% O2 like they used to. That’s the whole reason I got rid of all of my suuntos