Diving 32% Nitrox with "Air" Algorithms

[BRT]

Going all the way back to oceanic data plus, if you accidentally dive on FO2 21 you were stuck with it until you got a 24 hr break. One button navigation was the worst.

Just what is FO2 21?? Are you saying they would not change away from that to nitrox mixtures?

 

[arew+4]

Just what is FO2 21?? Are you saying they would not change away from that to nitrox mixtures?

No, if you did not set it for a dive it would revert 21%. With the one button back then it was easy to accidentally get into Nitrox mode and it would default to 21% changing to something else was difficult. So you would occasionally get stuck in 21% mode not a big problem, just a "glitch". As a bonus you got O2 sat numbers for free.

 

[BRT]

No, if you did not set it for a dive it would revert 21%. With the one button back then it was easy to accidentally get into Nitrox mode and it would default to 21% changing to something else was difficult. So you would occasionally get stuck in 21% mode not a big problem, just a "glitch". As a bonus you got O2 sat numbers for free.

21% is air. Never been a problem for me. And they only do that dance if you have them set to do that.

 

[Blackcrusader]

Maybe just your wording but Suunto's do not lock out for exceeding NDL (Sunnto's might) A Suunto only locks out if you do not follow the required decompression time that results from exceeding NDL. If decompression not carried out it locks out for 24 hours with aim of advising diver not to dive again during that period to reduce risk of DCS.
For me starting an ascent with 10 minutes of NDL remaining would be a waste of valuable bottom time. Dive times at 30 to 40 m are way too short anyway to waste 10 minutes.

Maybe read to the end of my sentence...... and they missed that deco obligation.

 

[Belzelbub]

21% is air. Never been a problem for me. And they only do that dance if you have them set to do that.

Yes. However some computers had an Air setting and a separate Nitrox setting. You could set for Air, or chose Nitrox 21. On those computers, setting for Air could create issues when later diving Nitrox.

No, if you did not set it for a dive it would revert 21%. With the one button back then it was easy to accidentally get into Nitrox mode and it would default to 21% changing to something else was difficult. So you would occasionally get stuck in 21% mode not a big problem, just a "glitch". As a bonus you got O2 sat numbers for free.

This sounds backwards to me. Are you saying that if you set it for FO2 21% you would not be able to change it to FO2 32% or something else for 24 hours, or that you wouldn't be able to change to Air until that 24 hours.

If so, that's not really an issue.

The problem on some of those computers was if you did the first dive in Air. If the computer did not track O2 while in Air mode, it would prevent switching to Nitrox mode on subsequent dives.

 

[arew+4]

Yes. However some computers had an Air setting and a separate Nitrox setting. You could set for Air, or chose Nitrox 21. On those computers, setting for Air could create issues when later diving Nitrox.

This sounds backwards to me. Are you saying that if you set it for FO2 21% you would not be able to change it to FO2 32% or something else for 24 hours, or that you wouldn't be able to change to Air until that 24 hours.

If so, that's not really an issue.

The problem on some of those computers was if you did the first dive in Air. If the computer did not track O2 while in Air mode, it would prevent switching to Nitrox mode on subsequent dives.

That's what I was saying, if you accidentally pressed and held the button on the gas screen before you got wet, it would go into EAN 21, and you would be stuck in that mode for 24hrs. You could adjust the O2 % as needed, just could not get back to Air for 24hrs. Like I said, not really a problem just annoying because of the one button control system.

 

[boulderjohn]

Yes. However some computers had an Air setting and a separate Nitrox setting. You could set for Air, or chose Nitrox 21. On those computers, setting for Air could create issues when later diving Nitrox.

That was how my first computer (a Suunto) worked. If you dived with it in air mode, you could not switch to nitrox for 24 hours. If you were regularly going back and forth between air and nitrox, you learned to keep it on nitrox and set it at 21 when diving air.

 

[BRT]

That's what I was saying, if you accidentally pressed and held the button on the gas screen before you got wet, it would go into EAN 21, and you would be stuck in that mode for 24hrs. You could adjust the O2 % as needed, just could not get back to Air for 24hrs. Like I said, not really a problem just annoying because of the one button control system.

How much more bottom time do you get with EAN 21 over air?

 

[arew+4]

How much more bottom time do you get with EAN 21 over air?

Zero, it's air, the computer does it to continue tracking your O2 levels incase you switch to actual enriched air greater than 21%.

 

[BRT]

Zero, it's air, the computer does it to continue tracking your O2 levels incase you switch to actual enriched air greater than 21%.

Yep, so why do you care what it is called?