OP
Blackcrusader
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Some of us experienced divers do average in the single digits on some dives.
THE "PERFECT ( being horizontal ) TRIM" HOAX
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Some of us experienced divers do average in the single digits on some dives.
That's what I said, > 6L/min. The best air consumption rate I've ever achieved was 6.4L/min with a baby cylinder, but usually I average 7.5-8.5L/min on most dives on normal AL80. 15L/min is the average consumption rate of SB divers according to survey, and I'm gonna call SB divers more experienced than average. All of my tech instructors average 14-16L/min too. I struggle to build a buddy team with consistent single digit air consumption rate on all dives. I have only been able to do that with Asian divers.
It has nothing to do with my question though. I was just confused about OC air vs CC O2 consumption in another comment. 0.8L/min isn't single digit, its 1/10 of a single digit, 1/10 of my typical consumption, 1/20 of an average experienced diver consumption. Hence my confusion.
It's almost like air is 20% oxygen.
Actually I've been wondering if there is any correlation between CC O2 consumption and OC air consumption? I don't know anything about CC, my first instinct was trying to convert using 21% but it didn't work because 21% is 1/5 not 1/10 or 1/20. Is CC O2 consumption more efficient than extracting O2 from OC air? Just saying that air is 1/5 O2 doesn't explain how CC O2 consumption is 10-20 times slower than OC air consumption.
We metabolize O2. Our O2 sensors measure how much O2 is left in the system and injects that through a solenoid, or the diver does it. The rest of the gas is scrubbed with sof-no-lime to remove the CO2, and we breathe the recycled mixture. That's why we call it CC or Closed Circuit. The most we can use while breathing is 21%. But, we also use some "dil" for our BC or if we vent any of our loop, so it's usually a bit less. Does that make sense?
It really shows how much O2 OC divers "waste" with every breath! Is there a ratio/formula you use to convert OC air consumption to CC O2 consumption?
Another dumb question (completely unimportant): does CC diving help with OC air consumption, like how freediving can help? What I mean is my knowledge and experience in freediving help me understand how my body metabolizes oxygen and regulate my breathing rate and mind/body relaxation accordingly. I can imagine diving CC would reinforce the "waste" in my mind but not sure if it would change anything in my OC diving?
(My brain comes up with a lot of dumb questions when I just wake up
apologies if my thoughts don't exactly make sense. Also apologies about the side track from the thread's topic lol)
The extraction is not, but on OC the residual O2 in an exhalation (about 17%) is lost along with everything else. On CC it's recirculated with a little top up to replace what was metabolized.
Not really. We plan to be able to finish a dive on OC (Open Circuit) just in case we have to bail out.
Quite the opposite. OC tends to slow breathe to conserve gas. We have to breathe a bit more aggressively to get rid of our CO2. CO2 retention is our biggest nemesis.
These are pretty common questions and not dumb at all.
As an aside, too many dives are planned as if nothing will go wrong. Tech divers soon learn to plan for everything to go wrong. It's safer that way.
I've been reading a bit more and it seems in the OC context the gas we breathe out is around 16% O2, meaning we use up around 5%. 5% is 1/20 the total volume of the air breathed. Maybe that explains why the CC O2 consumption rate could be more or less somewhere around 1/20 the OC air consumption rate?
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