21% Nitrox

[Rickk]

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

I only use Nitrox on multiple dive days, 3 or more in a day. The next day my Aqua Lung i330c will not allow me to switch back to air but will allow a 21% Nitrox mixture.

If I use Nitrox one day, then switch back to air for two dives a day for a week, it continues to force me to dive 21% Nitrox and not air.

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?

 

[tursiops]

 

[maadJurguer]

Because we are children and not to be trusted (in the eyes of outdoor companies)...but not all computers require it.

 

[BoltSnap]

Few computers don't allow you to change the "mode" on the computer until you have totally offgased according to their algorithm calculations (modes include Apnea/free diving, Nitrox, Air, Gauge). If you want to change back to "air" or 21% O2 mix, you just have to change the O2% in the mix option in your computer and not worry about changing it to the "Air" mode. It is annoying but they probably have a rationale for it but I don't know it.

 

[GreggS]

I keep mine in nitrox mode all the time for just this reason. 21% IS air and even shows I dived air when I download my dives to Subsurface.

 

[M-Cameron]

I assume so you don’t accidentally dive air in “nitrox” mode and nitrox in “air” mode.

Don’t want someone to inadvertently switch modes while fiddling with the computer and not realize it.... I imagine most people dive the same gas their entire trip.

Just my assumption.

 

[Bob DBF]

It could be the O2 clock is not run in Air mode. Just guessing.



Bob

 

[Nemrod]

If you do a 32% Nitrox dive number 1 (deeper) and want to use plain old air for dive number 2 (more shallow) as I often do then just set 21% for dive 2. And then be happy and dive, dive, dive. N

 

[NAM001]

My guess is that in air some metrics are not calculated. I have never heard of the OP's concern before. I have no backing for my guess at all.

Another reason to love my shearwater...

 

[Rickk]

If you do a 32% Nitrox dive number 1 (deeper) and want to use plain old air for dive number 2 (more shallow) as I often do then just set 21% for dive 2. And then be happy and dive, dive, dive. N

I typically only dive Nitrox when doing 3 or more in a day. Then if I am going back to 2 dives a day I'll just use air.

However I will dive Nitrox one day then dive 2 tanks air daily for a week but have to set for Nitrox at 21% not set for air.