How helpful would a CO2 monitor really be?

***ScubaDadMiami*** · 11th August 2006, 02:02

Example of overbreathing. (Credit: Richard Vann, Ph. D., Divers Alert Network). Notice how the overbreathing, if continued, builds up CO2.

***ScubaDadMiami*** · 11th August 2006, 02:36

Spent scrubber. Notice the direct and fast CO2 rise compared to overbreathing of the scrubber. (Credit: Richard Vann, Ph. D., Divers Alert Network).

decoweenie · 11th August 2006, 06:08

I can't quite follow the graphs since the text is too small for me, but the time scale suggests that it takes a long time.

E-man · 11th August 2006, 07:31

I can't see the graphs, but I agree with decoweenie, even at 300 fsw provided a detector can sense co2 before it hits 0.5% SEV one should have 'plently' (read enough) time to react (bail, flush ect)

Mdemon · 11th August 2006, 09:07

Quote: (Originally Posted by E-man)

What really high RMV rated duration testing done by AP are you refering to? Other than the 40RMV?

Speaking to someone in the factory they mentioned 70+ although my memory is a bit hazy. "Beyond what a human could achieve" springs to mind. If it's important, email APD? I don't think is bears much relevance here - we want to detect an event, not worry about its cause yet.

Padowan · 11th August 2006, 10:15

How about this for a radical idea.....

If you feel a bit strange, bail out, see if you feel less strange.
If you feel less strange, then you can determine that somethings not right with the loop.
Check and validate O2 levels, if these are OK, then it's probably something to do with CO2, either a channel, a breakthrough or a duff batch of lime.
If it's a CO2 incident, then you're not going back on the loop for a while if at all, so start making your ascent of the adequate OC bailout that you (or your team) carry.
You could try getting back on the loop in the shallows and closely monitor how you feel, it may have been a scrubber loading due to the depth you were at, and the scrubber works again in the shallows for a bit longer.

This is what I'll be doing for the time being, until there's a proven CO2 meter that gives some useful, qualtifyable and validatable information.

AD_ward9 · 11th August 2006, 10:33

Quote: (Originally Posted by Mdemon)

Speaking to someone in the factory they mentioned 70+ although my memory is a bit hazy. "Beyond what a human could achieve" springs to mind. If it's important, email APD? I don't think is bears much relevance here - we want to detect an event, not worry about its cause yet.

APD, and everyone else involved with EN14143 testing, will have tested at least to an RMV of 75l/min, as required by Section 5.6.1 and Table 4 of the standard.
This is not beyond what a human can achieve: it is easy to get well above it for short periods, hyperventilating.
Alex

Mdemon · 11th August 2006, 12:04

Quote: (Originally Posted by Padowan)

How about this for a radical idea.....

If you feel a bit strange, bail out, see if you feel less strange.
If you feel less strange, then you can determine that somethings not right with the loop.
Check and validate O2 levels, if these are OK, then it's probably something to do with CO2, either a channel, a breakthrough or a duff batch of lime.
If it's a CO2 incident, then you're not going back on the loop for a while if at all, so start making your ascent of the adequate OC bailout that you (or your team) carry.
You could try getting back on the loop in the shallows and closely monitor how you feel, it may have been a scrubber loading due to the depth you were at, and the scrubber works again in the shallows for a bit longer.

This is what I'll be doing for the time being, until there's a proven CO2 meter that gives some useful, qualtifyable and validatable information.

You might be waiting a while for something giving you "qualtifyable" information...

**Gill Envy** · 11th August 2006, 17:18

Quote: (Originally Posted by AD_ward9)

APD, and everyone else involved with EN14143 testing, will have tested at least to an RMV of 75l/min, as required by Section 5.6.1 and Table 4 of the standard.
This is not beyond what a human can achieve: it is easy to get well above it for short periods, hyperventilating.
Alex

Even though someone can not sustain 75 l/min, if i understand correctly and as you've pointed out, a sharp short term spike during a period of panic or extreme exertion could conceivably exceed this. If this were to happen, dwell time would be sufficiently reduced that you would not see a nice slow rise in PCo2 but a dramatic, short term spike, right? I'm guessing that killer breakthrough of this type (as apposed to exhausted sorb) can happen suddenly under extreme circumstances, like the situations people get in when things go south (strong currents, multiple failures, panic etc.). I would think that for a Co2 meter to be useful in such situations it would have to be able to catch a change of 1/2 a % (on a deep dive anyway) rapidly and the diver would have to react immediately. are there any examples of other types of meters that are that sensitive and stable?

if my experience with moist O2 sesnors is indicative, I just can't imagine how a meter would be created that would not be throwing false alarms every time the voltage fluctuated. Again, still dubious, but very intrigued and looking forward to the first model hitting the market.

11th August 2006, 06:08	#23 (permalink)
decoweenie Crash Test Dummy Current Rebreather/s: Other CCR Other Rebreather/s: Other CCR Join Date: Feb 2005 Location: Cairo Posts: 5,487	Re: How helpful would a CO2 monitor really be? I can't quite follow the graphs since the text is too small for me, but the time scale suggests that it takes a long time. __________________ "...after a while you get bored offering advice to a bull that like to keep butting the fence with its head rather than walking through the open gate..." - Rebreather World PM
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11th August 2006, 07:31	#24 (permalink)
E-man On the loop! Current Rebreather/s: Inspiration Classic Optima Other Rebreather/s: Titan Join Date: Sep 2005 Location: Eastern Coast ;) Posts: 212	Re: How helpful would a CO2 monitor really be? I can't see the graphs, but I agree with decoweenie, even at 300 fsw provided a detector can sense co2 before it hits 0.5% SEV one should have 'plently' (read enough) time to react (bail, flush ect)
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11th August 2006, 09:07	#25 (permalink)
Mdemon SiegeEngine II Current Rebreather/s: Inspiration Classic Home Build Other Rebreather/s: Inspiration Classic Home Build Join Date: Feb 2007 Location: SWUK Posts: 1,927	Re: How helpful would a CO2 monitor really be? Quote: (Originally Posted by E-man) What really high RMV rated duration testing done by AP are you refering to? Other than the 40RMV? Speaking to someone in the factory they mentioned 70+ although my memory is a bit hazy. "Beyond what a human could achieve" springs to mind. If it's important, email APD? I don't think is bears much relevance here - we want to detect an event, not worry about its cause yet. __________________ www.southwestmafia.com "small minds talk about people, Average Minds Talk About Events, GREAT MINDS TALK ABOUT IDEAS!" The WRONG Attitude will get you killed. "Once the agenda-monkeys and perfect-worlders have moved on, perhaps we can do some diving?"
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11th August 2006, 10:15	#26 (permalink)
Padowan Proper Boffin Current Rebreather/s: Inspiration Classic Other Rebreather/s: Join Date: Feb 2005 Location: Kent, UK. Posts: 518	Re: How helpful would a CO2 monitor really be? How about this for a radical idea..... If you feel a bit strange, bail out, see if you feel less strange. If you feel less strange, then you can determine that somethings not right with the loop. Check and validate O2 levels, if these are OK, then it's probably something to do with CO2, either a channel, a breakthrough or a duff batch of lime. If it's a CO2 incident, then you're not going back on the loop for a while if at all, so start making your ascent of the adequate OC bailout that you (or your team) carry. You could try getting back on the loop in the shallows and closely monitor how you feel, it may have been a scrubber loading due to the depth you were at, and the scrubber works again in the shallows for a bit longer. This is what I'll be doing for the time being, until there's a proven CO2 meter that gives some useful, qualtifyable and validatable information. __________________ Padowan The future's bright, the future's Yellow .....for now padowan.net - Latest Video: Scapa Flow Rebreather Diving
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11th August 2006, 10:33	#27 (permalink)
AD_ward9 So much more to learn Current Rebreather/s: Other CCR Other Rebreather/s: Other CCR Join Date: Jun 2005 Location: Scotland Posts: 1,868	Re: How helpful would a CO2 monitor really be? Quote: (Originally Posted by Mdemon) Speaking to someone in the factory they mentioned 70+ although my memory is a bit hazy. "Beyond what a human could achieve" springs to mind. If it's important, email APD? I don't think is bears much relevance here - we want to detect an event, not worry about its cause yet. APD, and everyone else involved with EN14143 testing, will have tested at least to an RMV of 75l/min, as required by Section 5.6.1 and Table 4 of the standard. This is not beyond what a human can achieve: it is easy to get well above it for short periods, hyperventilating. Alex Last edited by AD_ward9 : 11th August 2006 at 10:38.
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11th August 2006, 12:04	#28 (permalink)
Mdemon SiegeEngine II Current Rebreather/s: Inspiration Classic Home Build Other Rebreather/s: Inspiration Classic Home Build Join Date: Feb 2007 Location: SWUK Posts: 1,927	Re: How helpful would a CO2 monitor really be? Quote: (Originally Posted by Padowan) How about this for a radical idea..... If you feel a bit strange, bail out, see if you feel less strange. If you feel less strange, then you can determine that somethings not right with the loop. Check and validate O2 levels, if these are OK, then it's probably something to do with CO2, either a channel, a breakthrough or a duff batch of lime. If it's a CO2 incident, then you're not going back on the loop for a while if at all, so start making your ascent of the adequate OC bailout that you (or your team) carry. You could try getting back on the loop in the shallows and closely monitor how you feel, it may have been a scrubber loading due to the depth you were at, and the scrubber works again in the shallows for a bit longer. This is what I'll be doing for the time being, until there's a proven CO2 meter that gives some useful, qualtifyable and validatable information. You might be waiting a while for something giving you "qualtifyable" information... __________________ www.southwestmafia.com "small minds talk about people, Average Minds Talk About Events, GREAT MINDS TALK ABOUT IDEAS!" The WRONG Attitude will get you killed. "Once the agenda-monkeys and perfect-worlders have moved on, perhaps we can do some diving?"
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11th August 2006, 17:18	#29 (permalink)
Gill Envy Shearwater Copis Divers Current Rebreather/s: Other CCR Other Rebreather/s: Evolution Other CCR Join Date: Nov 2005 Location: seattle Posts: 1,315	Re: How helpful would a CO2 monitor really be? Quote: (Originally Posted by AD_ward9) APD, and everyone else involved with EN14143 testing, will have tested at least to an RMV of 75l/min, as required by Section 5.6.1 and Table 4 of the standard. This is not beyond what a human can achieve: it is easy to get well above it for short periods, hyperventilating. Alex Even though someone can not sustain 75 l/min, if i understand correctly and as you've pointed out, a sharp short term spike during a period of panic or extreme exertion could conceivably exceed this. If this were to happen, dwell time would be sufficiently reduced that you would not see a nice slow rise in PCo2 but a dramatic, short term spike, right? I'm guessing that killer breakthrough of this type (as apposed to exhausted sorb) can happen suddenly under extreme circumstances, like the situations people get in when things go south (strong currents, multiple failures, panic etc.). I would think that for a Co2 meter to be useful in such situations it would have to be able to catch a change of 1/2 a % (on a deep dive anyway) rapidly and the diver would have to react immediately. are there any examples of other types of meters that are that sensitive and stable? if my experience with moist O2 sesnors is indicative, I just can't imagine how a meter would be created that would not be throwing false alarms every time the voltage fluctuated. Again, still dubious, but very intrigued and looking forward to the first model hitting the market. __________________ Gill Envy ...Because I wasn't born with gills! ><(°>><(°>><(°>><(°>><(°>><(°>><(°>><(°> Last edited by Gill Envy : 11th August 2006 at 17:22.
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