Nitrox Question.

[Hamster]

"Slight correction Big-T - PADI teaches 1.4 for planning with a max (which other agencies agree with though no one rally has any proof) of 1.6 for emergency or contingency situations.

The problem with pp02 is no one really knows. I am sure we all know or have heard of people that have dived deeper than 66m on air and lived to tell the tale - though I would personally not advise trying it."


I think you'll find that if you want to keep your PPO2 below 1.4 then the maximum depth on air is 57 meters not 66. I suspect you may have forgotten that there is one atmosphere of pressure at the surface. I would also not advise a 57 meter dive on air as narcosis would be becoming something of an issue.

 

[Jonathan]

but a pp02 of 1.6 gives you 66m.

I am sure you've heard of Mark what's his name that did 150m + but came back alive.

I personally stick to the 1.4 rule unless doing accelerated deco when there are other factors (safety divers for one) involved....

Jonathan

 

[Hamster]

Yup I agree that a PP02 of 1.6 requires a depth of 66 meters when breathing air but if you restrict yourself to the safer 1.4 then the max depth is 57 meters. The risk of oxygen toxicity is too high to start playing silly games. I suspect that some of the unexplained scuba deaths are probably due to the diver receiving an O2 hit.

Recently I read a report of a death of a diver breathing EAN32 at a depth of 40 meters which gives a PPO2 of 1.6. In this case there were some other contributing factors like using EAN50 for decompression and breathing 100% O2 on the surface. So my conclusion is that a PPO2 of 1.6 might be ok for a short duration in an emergency but it isn't something to plan.

 

[Jonathan]

can we agree that we agree Hamster?

 

[Hamster]

Yup … I'm happy to agree that we agree. I (mis) read your first post on this topic as saying that a dive to 66 meters on air would give a PPO2 of 1.4 whereas we both know that the correct figure is 1.6.