Partial Pressure of Oxygen

[Razorblade]

What is the fatal partial pressure of oxygen?
I've heard figures from 1.6 ATM absolute to 2.0 ATM absolute. Is it a definite number or like no deco time which is different for every person?

 

[O-ring]

...different strokes for different folks. And different folks tox at different levels at different times.

 

[Razorblade]

That's what I wanted to know, thanks.
So what's the "safe" partial pressure? In other words: below what ATM absolute should I keep it?

 

[Walter]

Are you playing with nitrox without the training?

 

[Big-t-2538]

standards from every agency that have been tested and tested....the general consensus is that if you're in the water 1.6 is the absolute "safe" max...I say safe because each person is different and by pushing the limits you can easily get yourself (and buddy) injured.

Right now I am doing some research and trying to gather as much info as I can regarding deco theory and such, and ppo2 is a concern, or topic of discussion.

If you are doing a recreational dive and do not have technical dive training, you have no business pushing the ppo2 above 1.4

 

[leadweight]

During early experiments with pure O2 rebreathers, Jacques Cousteau was said to black out at 45 feet, corresponding to a PO2 of just under 2.4. I suppose he would have died had he been alone. Don't try this at home, as they say.

 

[CincyBengalsFan]

Commercial Divers routinely every day on this planet go thru chamber runs of 100% O2 at 2.25 And actually go up to 2.82 and are still OK. These guys are motionless in the chamber though.

All the reference you can dream of is in the Navy Manuals.

 

[CincyBengalsFan]

But like BigT said...Keep it under 1.4.

 

[ERP]

leadweight once bubbled...
During early experiments with pure O2 rebreathers, Jacques Cousteau was said to black out at 45 feet, corresponding to a PO2 of just under 2.4. I suppose he would have died had he been alone. Don't try this at home, as they say.

The version of this story that I read, states that he did this not once but twice, before deciding that O2 rebreathers were a bad idea.

 

[Rick Murchison]

Highly variable. In one experiment at 3.1 ATA O2, OxTox hits ranged from under 5 minutes exposure to over 160 minutes exposure. In other experiments it appears that the average time to a hit in 10% of the test subjects ran roughly along a straight line when PO2 and Time are both plotted by log, with the average time to hit at 1 minute at about 8.5 ATA and an average time of 100 minutes at about 1.8 ATA. But again, on an individual basis the numbers are highly variable, and the bottom line is that one should remain well within the established NOAA time limits and endeavor to remain below the recommended limiting PO2 of 1.4 ATA, and not even accidentally exceed the maximum limiting PO2 of 1.6.
Note that in a chamber where higher PO2's are routinely used, an occasional O2 hit is no big deal, but underwater it is almost always fatal.
Rick