Oxygen Usage

Janos · 26th January 2006, 18:38

About one litre / min on the dive, and the same again on the ascent! Ie on a 60 min dive I use about 20 bar on the dive, and 20 bar on the ascent.

Janos

Underwaterbear · 26th January 2006, 20:14

Lately I'm averaging around 1.5 -1.8 Lpm depending how often I flush on deco...ie if I'm manually bumping the ppO2 up on deco I use a fair bit more.

Thats based on 50m 30min bt dives.

I'm with Phi, 2Lpm seems a good planning number.

Cheers
Andrew

jaap · 26th January 2006, 21:05

Quote: (Originally Posted by PeteS)

Oh, you must mean Van der Waals equations.

These deal with the fact that gasses do not act as an ideal gas, and you don't always get what you thought you were going to get. Sometimes more, sometimes less, depends on the gas....

Yeah yeah, but please note this part:
"from real measurements, no simulations"

Sometimes thermodynamics, real gas laws and things like that can be extremely decpetive if one tries to use rather simple equations thinking they describe what is really happening.

A rather basic thing like the vdw real gas law is not to be trusted blindly as a law describing reality.

So the data is _not_ from an vdw-simulation but measurements from _real_ experiments. (But they agree quite well with vdw...)

Deep Thought · 31st January 2006, 15:00

Quote: (Originally Posted by Steve)

Disregarding actual metabolic oxygen consumption and focusing on actual gas used; how many litres of O2 do you guys use per minute?

After years of disregarding logs, I started tracking my dives on a small note book that recorded gas use and other parameters that I thought would influence the operation of the unit. Now teaching the ccr course I stress that students keep a log of the following items so they can reflect back and see if performance or operations change:

oxygen used in bar
dil used in bar
time
depth
battery change
cell change
scrubber used
etc...Anything to influence a dive...

The ability to monitor use of gas can show a new diver how efficient or inefficient they may be with adding or possibly venting gas from the loop. Other records are just good common sense to track use of consumables.

Good post as it is valuable to see what people feel they use, as mentioned not actual metabolic but gas used. It always amazes me when I see text that quote 2-3 liters per minute of oxygen metabolic consumption??? who?

DT

View Poll Results: How many litres of O2 per minute do you use?
1.0 lpm or less	33	46.48%
1.25 lpm	10	14.08%
1.5 lpm	14	19.72%
1.75 lpm	5	7.04%
2.0 lpm	7	9.86%
2.25 lpm or more	2	2.82%
Voters: 71. You may not vote on this poll

26th January 2006, 18:38	#21 (permalink)
Janos "Two Sheds" Current Rebreather/s: Classic Kiss Other Rebreather/s: Classic Kiss Join Date: Feb 2005 Location: East Surrey Posts: 602	Re: Oxygen Usage About one litre / min on the dive, and the same again on the ascent! Ie on a 60 min dive I use about 20 bar on the dive, and 20 bar on the ascent. Janos __________________ You can lead a horse to water but you can't climb a ladder with a large bell in both hands - Vic Reeves www.hellfins.com/shed
(Offline)

26th January 2006, 20:14	#22 (permalink)
Underwaterbear A Prismer in Megland Current Rebreather/s: Prism Topaz Other Rebreather/s: Join Date: May 2005 Location: Seattle, WA Posts: 192	Re: Oxygen Usage Lately I'm averaging around 1.5 -1.8 Lpm depending how often I flush on deco...ie if I'm manually bumping the ppO2 up on deco I use a fair bit more. Thats based on 50m 30min bt dives. I'm with Phi, 2Lpm seems a good planning number. Cheers Andrew
(Offline)

26th January 2006, 21:05	#23 (permalink)
jaap Normal people worry me Current Rebreather/s: Classic Kiss Other CCR RB80 / Clone Ray Other SCR Home Build Other Rebreather/s: Other CCR RB80 / Clone Ray Other SCR Home Build Join Date: Jun 2005 Location: Stockholm Sweden Posts: 453	Re: Oxygen Usage Quote: (Originally Posted by PeteS) Oh, you must mean Van der Waals equations. These deal with the fact that gasses do not act as an ideal gas, and you don't always get what you thought you were going to get. Sometimes more, sometimes less, depends on the gas.... Yeah yeah, but please note this part: "from real measurements, no simulations" Sometimes thermodynamics, real gas laws and things like that can be extremely decpetive if one tries to use rather simple equations thinking they describe what is really happening. A rather basic thing like the vdw real gas law is not to be trusted blindly as a law describing reality. So the data is _not_ from an vdw-simulation but measurements from _real_ experiments. (But they agree quite well with vdw...)
(Online)

31st January 2006, 15:00	#24 (permalink)
Deep Thought Custom Title Allowed! Current Rebreather/s: Inspiration Vision Classic Kiss Other Rebreather/s: Inspiration Classic Inspiration Vision Evolution Megalodon Sport Kiss Classic Kiss Optima Join Date: Apr 2005 Location: Great Lakes Posts: 190	Re: Oxygen Usage Quote: (Originally Posted by Steve) Disregarding actual metabolic oxygen consumption and focusing on actual gas used; how many litres of O2 do you guys use per minute? After years of disregarding logs, I started tracking my dives on a small note book that recorded gas use and other parameters that I thought would influence the operation of the unit. Now teaching the ccr course I stress that students keep a log of the following items so they can reflect back and see if performance or operations change: oxygen used in bar dil used in bar time depth battery change cell change scrubber used etc...Anything to influence a dive... The ability to monitor use of gas can show a new diver how efficient or inefficient they may be with adding or possibly venting gas from the loop. Other records are just good common sense to track use of consumables. Good post as it is valuable to see what people feel they use, as mentioned not actual metabolic but gas used. It always amazes me when I see text that quote 2-3 liters per minute of oxygen metabolic consumption??? who? DT __________________ Creature Of Habits; Mostly Bad www.gudcscuba.com
(Offline)

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