EAN32 diver below you at 40-odd meters?

[peterbj7]

Dan Kerem (2000) of the Israeli Navy Medical Institute, "I'll stress again that with pure oxygen diving, as long as your gear is okay and there is no CO2 buildup in the system, divers routinely dive for hours at 1.6 atm with no incidence of oxygen convulsion."

Perhaps. I have witnessed several exceedingly experienced divers all of who suffered respiratory difficulties (and in one case vision disturbance) after using their CCRs set to pO2 of 1.3 during two long dives a day for four days. They had to lay off diving for 24/36 hours. I have personally experienced mild discomfort towards the end of a single 4 hour CCR dive where I had pO2 set to 1.3. I now take Tom Mount's advice and dial it back to 1.2 or 1.1 for long dives, and even 1.0 if there will be many of them.

 

[Slamfire]

Perhaps. I have witnessed several exceedingly experienced divers all of who suffered respiratory difficulties (and in one case vision disturbance) after using their CCRs set to pO2 of 1.3 during two long dives a day for four days. They had to lay off diving for 24/36 hours. I have personally experienced mild discomfort towards the end of a single 4 hour CCR dive where I had pO2 set to 1.3. I now take Tom Mount's advice and dial it back to 1.2 or 1.1 for long dives, and even 1.0 if there will be many of them.

Very interesting. Respiratory difficulty sounds more like pulmonary toxicity rather than CNS. By going 4 hrs at 1.3 you broke the oxygen clock - max at 1.3 = 3hrs. But I recently learned that the oxygen clock for 1.4 and below was set using pulmonary toxicity as the limiting factor, which makes sense with what you're saying. It seems that they got the pulmonary hit before getting the CNS hit. So there is still some use for the oxygen clock.

The one case of vision disturbance goes more in line with VENTID ie CNS.

 

[Makhno]

Thanks, everyone, for your replies. There's a lot of good stuff (data, anecdotes, opinions, etc.) in your posts and in your links.

Cheers and safe diving,
M

 

[bracko]

not sure if it's been mentioned or not, but why no tank rattle/water whistle/tank banger???

apart from mask and fins it was the first thing i bought.

 

[vjanelle]

Cold water diving? You'll never hear that through a hood.

(For varying degrees of "never")