21% Nitrox

[CaveSloth]

Shearwater

 

[dmaziuk]

Can anyone explain why dive computers will force a 24 hour wait to switch to air after diving Nitrox?

Because they're dumb.

Why are computers programed to force continued use of Nitrox when there is no reason to do so? Why would they allow a 21% mix when that is effectively the same thing?

Most likely, as others said, they're not running oxtox counter in "air mode". That is a brain-dead design decision, even if they had reasons for it that sounded good at the time.

 

[Ontwreckdiver]

I just leave mine in Nitrox mode all the time.

 

[EFX]

It's possible, but not likely, that the reason for not having the ability to switch from EAN to air is due to programming constraints. In my spreadsheet I calculate oxygen accumulation for all segments of the dive regardless of gas mix which doesn't require any different programming between the two modes. The most likely reason is expressed by undercurrent.org:

"Some divers who get such warnings after doing repetitive dives on Nitrox switch to air to slow down oxygen accumulation. When doing this, it's best to keep one's computer in the Nitrox mode, so you can continue to track the P02 display. Some computers, such as Suuntos, won't allow you to switch to air mode for a day or two after diving in Nitrox mode. If you decide to breathe air after Nitrox, Jim Clymer, of Suunto's Technical Department, recommends setting the Nitrox mode for 21 percent, the equivalent of air."

The PO2 display that undercurrent.org refers to is probably the oxygen accumulation or the so-called oxygen clock.

 

[BackAfter30]

"Jim Clymer, of Suunto's Technical Department, recommends setting the Nitrox mode for 21 percent, the equivalent of air."

The PO2 display that undercurrent.org refers to is probably the oxygen accumulation or the so-called oxygen clock.

This is more of the same as has been said by others. It makes me wonder what the benefits are for those particular DCs of running the Air portion of the program rather than the Nitrox portion of the program. I'd be surprised to learn that the Nitrox calcs are so much more taxing that there is a battery life hit. Why not make everything Nitrox behind the scenes.

 

[Rickk]

It's possible, but not likely, that the reason for not having the ability to switch from EAN to air is due to programming constraints. ....

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?

Now my electronic dive log is wrong because it shows a lot of Nitrox dives which are recorded as 21% Nitrox when they were in air. I cannot change the log. I use DiverLog+.

 

[tursiops]

Now my electronic dive log is wrong because it shows a lot of Nitrox dives which are recorded as 21% Nitrox when they were in air.

How does it matter? Do you think air is not the same as 21% Nitrox?

 

[Rickk]

How does it matter? Do you think air is not the same as 21% Nitrox?

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.

 

[drk5036]

How does it matter? Do you think air is not the same as 21% Nitrox?

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...

 

[Wookie]

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.

I am an engineer and a scientist, and not all engineers are quite so pedantic. Precision is the enemy of close enough.