Interesting comments on diving with pure oxygen.
psteggle
New Member
OK OK. To deal with one post at a time
Effattah, CO2 narcosis? You surely mean CO2 build up causing shallow water blackout. Narcosis is normally caused by Nitrogen levels being high, hence using Helium mixes on deep stuff. These days, O2 is also regarded as slightly narcotic.
Jon, You are correct in that pure O2 can get interesting below 6m, as the PPO2 has risen to over 1.6 bar. But, my rebreather runs my PPO2 at two set points, 0.7 for shallow, and 1.3 for depth, and varies the O2% according to depth.
Stoddelle, You CAN breath pure O2 underwater, provided you monitor the following. PPO2 levels (max 1.4 bar for depth, 1.6 bar for decompression), CNS (central nervous system) exposure, and OTU's (Oxygen toxicity units).
All the above adds up to:- Any O2 mix can be used, provided that you monitor PPO2 levels, CNS and OTU's, and times.
More information about the above can be obtained from IANTD, TDI, and these days, even PADI.
Effattah, CO2 narcosis? You surely mean CO2 build up causing shallow water blackout. Narcosis is normally caused by Nitrogen levels being high, hence using Helium mixes on deep stuff. These days, O2 is also regarded as slightly narcotic.
Jon, You are correct in that pure O2 can get interesting below 6m, as the PPO2 has risen to over 1.6 bar. But, my rebreather runs my PPO2 at two set points, 0.7 for shallow, and 1.3 for depth, and varies the O2% according to depth.
Stoddelle, You CAN breath pure O2 underwater, provided you monitor the following. PPO2 levels (max 1.4 bar for depth, 1.6 bar for decompression), CNS (central nervous system) exposure, and OTU's (Oxygen toxicity units).
All the above adds up to:- Any O2 mix can be used, provided that you monitor PPO2 levels, CNS and OTU's, and times.
More information about the above can be obtained from IANTD, TDI, and these days, even PADI.
psteggle
New Member
Yup, the biggest threat to techy divers is Ox Tox. Onset is sudden, and even if you get a warning it's probably too late. Warning apparently take the form of facial twitches, metallic taste in mouth, plus others I cannot remember. Me and a friend of mine were in a recompression chamber for 5.5 hours after getting bent. We were on Pure O2 at a depth of 18m. That's a PPO2 of 2.8 bar!!!!! Double the normal scuba limit of 1.4 bar. He got facial twitches and very fast reactions from the chamber operators. I got nothing at all. Ox tox, like narcosis, is very personal, and no one can tell you why.
I'm told that the process is as follows:- You blackout, you fit, you relax, and still blacked out, you let the mouthpeice out and drown. Easy really.
CO2 retention is usually caused by divers "skip breathing" to try and extend gas usage. Not a problem on a CCR.
TTFN
Pete S
I'm told that the process is as follows:- You blackout, you fit, you relax, and still blacked out, you let the mouthpeice out and drown. Easy really.
CO2 retention is usually caused by divers "skip breathing" to try and extend gas usage. Not a problem on a CCR.
TTFN
Pete S
WilBriK
New Member
O2
During high school, I was a lifeguard for Dade County.
Many of the places I guarded at had O2 tanks to administer to people in the event of a medical emergency.
The other guards and I, for the sake of freaking people out, would hyperventilate on the O2 for a few minutes, take a good, long, deep breath of pure oxygen and slowly walk into the water, making sure everyone in the swimming area of the lake could see us. The breathing was all done inside the lifeguard shack so no one could see what we were up to.
We were allowed to pass 'The Line' that seperated the safe, shallow part of the lake from the dangerous, deep part. Every kid from every summer camp dreamed of crossing that line, but they knew it meant 15 minutes of embarrasing punishment ladled out by bored lifeguards in full view of their friends when they got caught, so most didn't do it.
Anyway, we would make sure everyone saw us cross the line, then we would submerge out of sight and swim to a buoy that was about 15 feet away from the rope. This buoy had a heavy metal bar attached to the bottom of it to help prevent it from drifting, so we would latch on to that and wait. And wait. And wait and wait and wait.
Even the O2 hogs in the group could stay under for 4 minutes, with the more efficient breathers getting around 7 minutes downtime.
After we started feeling the need to breathe, we would casually swim back under the rope, as if nothing special had happened. There would be 50 or 60 kids and about 10 counselors, all staring wide-eyed in disbelief.
The hardest part was keeping a straight face.
During high school, I was a lifeguard for Dade County.
Many of the places I guarded at had O2 tanks to administer to people in the event of a medical emergency.
The other guards and I, for the sake of freaking people out, would hyperventilate on the O2 for a few minutes, take a good, long, deep breath of pure oxygen and slowly walk into the water, making sure everyone in the swimming area of the lake could see us. The breathing was all done inside the lifeguard shack so no one could see what we were up to.
We were allowed to pass 'The Line' that seperated the safe, shallow part of the lake from the dangerous, deep part. Every kid from every summer camp dreamed of crossing that line, but they knew it meant 15 minutes of embarrasing punishment ladled out by bored lifeguards in full view of their friends when they got caught, so most didn't do it.
Anyway, we would make sure everyone saw us cross the line, then we would submerge out of sight and swim to a buoy that was about 15 feet away from the rope. This buoy had a heavy metal bar attached to the bottom of it to help prevent it from drifting, so we would latch on to that and wait. And wait. And wait and wait and wait.
Even the O2 hogs in the group could stay under for 4 minutes, with the more efficient breathers getting around 7 minutes downtime.
After we started feeling the need to breathe, we would casually swim back under the rope, as if nothing special had happened. There would be 50 or 60 kids and about 10 counselors, all staring wide-eyed in disbelief.
The hardest part was keeping a straight face.
