whats your p02

Please register or login

Welcome to ScubaBoard, the world's largest scuba diving community. Registration is not required to read the forums, but we encourage you to join. Joining has its benefits and enables you to participate in the discussions.

Benefits of registering include

  • Ability to post and comment on topics and discussions.
  • A Free photo gallery to share your dive photos with the world.
  • You can make this box go away

Joining is quick and easy. Log in or Register now!

FYI with caveats, from Joel Silverstein a while back:
. . .We removed the Exceptional Exposure Oxygen tables from the NOAA diving manual 4th editon because there was fear that if the general public saw them printed that they might take it as an endorsement to use them.

The NOAA exceptional exposure limits are set for extreme emergencies only and are not for routine use. I.E: should be used for life saving only.

These are for a working dive meaning with lite exertion. Remember that there are a variety of factors that come into oxygen toxicity, and crossing the 1.6 atm 45min line does not guarantee convulsion, it also does not guarantee it won't.

NOAA OXYGEN
EXCEPTIONAL EXPOSURE LIMITS
PO2| Minutes

2.8 5
2.4 10
2.0 30
1.9 45
1.8 60
1.7 75
1.6 120
1.5 150
1.4 160
1.3 240


As you can see the exceptional times allow you a fairly large margin to use this method for an "escape." The table is NOT linear. Note that exceptional exposures are DANGEROUS and can only be done once in a day. . .
My personal physiological deep air depth limit was a solo dive descent approaching 60m in the Nagano Maru's cargo hold, Chuuk Lagoon 2007: Started seeing the "starfield simulation Windows screen saver" all around me, which at the time I thought was due to the severe nitrogen narcosis at 7 ATA ambient pressure (immediately ascended out of the cargo hold and stayed on the deck around 45 to 51m for the duration of the dive). In retrospect however after reading some Rubicon articles, the effect could also have been the beginning symptoms of an Ox-tox event just as well (PO2 at 1.5 ATA). . ,
 
Even rounding everything up--60m to 197', 20.9% O2 to .21, 1 ATM of tropical seawater to 33' exactly rather than the 33.X' it actually would be--I still only get 1.46 for that dive. Were you working hard or on a repetitive dive with deep air/O2 deco? Obviously, a tox event can and has happened below 1.4, so I'm not trying to discount it so much as I'm curious about a relatively rare event.
 
I run 1.4 for everything, can't be bothered to change these settings.
 
pO2=1.4 for deco when solo

Except I won't use 100% oxygen below 10 feet when I am alone.
 
I've been as high as 2.2, but like to keep it at 1.6 or below (a maximum of 1.2 in the loop on CCR).
 
Max PO2 1.5 for ordinary dives, Max. PO2 1.4 for cold water or demanding dives. Same thing for solo or buddies diving.
 
I dive OC and do same as in teamdiving. So 1.6 during deco. bottomgas max 1.4, but mostly I choose less.
 

Back
Top Bottom