1-cell vs 3-cell monitoring

OceanOpportunity · 19th May 2007, 03:57

ok, now for some controversy...

Preferences, and why?: 1 or 3 cell PO2 monitoring on kiss-type systems..i.e. no fancy voting logic computers/electronics. in 'theory' if the monitor were calibrated with 1 cell at 100% O2 and cross checked with air at the surface, and periodic dil flush checks were made during the dive, then...there should be a degree of confidence with the system. Or, two independent single-cell displays to cross check at most.

thoughts?

sven · 19th May 2007, 09:57

Recommended reading: How many sensors

Personnal opinion for mCCR:
- one sensor is OK most particulary if you dive with a fixed orifice, known dil and usual depth ( for you ), with some experience the "normal" PO2 is quite instinctively estimated, and you rather quickly notice an unusual reading.
I do it from time to time and never felt in danger

-two sensors is optimal

-three sensors is perhaps not a good idea on mCCR because there is a risk to "think" like a simple stupid voting logic and to vote out the only good sensor.

**Dave Sutton** · 19th May 2007, 13:40

Duh.......

Two minimum.

Three lets you keep diving for the rest of the week if one craps out.

Voting between them is easy: Flood with diluent and do basic math.

One is unsafe. Yes, you can get away with it (I have), but it's really dumb. If you came aboard EXPLORER, a place where I encourage innovation and homebuilts, I would not allow you in the water with a single cell CCR of any sort. Take that for what it's worth, from a dedicated minimalist/alpinist with a really open mind. This is just about the only thing I would put my foot down over. Don't do it.

Dave

19th May 2007, 03:57	#1 (permalink)
OceanOpportunity for a world of water Current Rebreather/s: Other CCR Dolphin Home Build Other Rebreather/s: Not Bought Yet Inspiration Classic Other CCR Dolphin Home Build Join Date: Nov 2006 Location: Providence, RI USA Posts: 596	1-cell vs 3-cell monitoring ok, now for some controversy... Preferences, and why?: 1 or 3 cell PO2 monitoring on kiss-type systems..i.e. no fancy voting logic computers/electronics. in 'theory' if the monitor were calibrated with 1 cell at 100% O2 and cross checked with air at the surface, and periodic dil flush checks were made during the dive, then...there should be a degree of confidence with the system. Or, two independent single-cell displays to cross check at most. thoughts? __________________ Michael Lombardi Oceans of Opportunity www.oceanopportunity.com Elected Director, Society for Human Performance in Extreme Environments MN'07, The Explorers Club Project Manager, Diving a Dream
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19th May 2007, 09:57	#2 (permalink)
sven Blogs Admin / Forum Mod Current Rebreather/s: Inspiration Classic Other Rebreather/s: Evolution Join Date: Nov 2005 Location: Sydney Posts: 551	Re: 1-cell vs 3-cell monitoring Recommended reading: How many sensors __________________ Regards, Sven The Sydney Project website: http://www.sydneyproject.com My Blog: http://sven.rebreatherworld.com "Whenever you find yourself on the side of the majority, it's time to pause and reflect." Mark Twain
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19th May 2007, 12:27	#3 (permalink)
Marc T hell is in the details Current Rebreather/s: RB80 / Clone Home Build Other Rebreather/s: Not Bought Yet RB80 / Clone Home Build Join Date: Sep 2005 Location: FRANCE Carcassonne Posts: 498	Re: 1-cell vs 3-cell monitoring Quote: (Originally Posted by sven) Recommended reading: How many sensors Personnal opinion for mCCR: - one sensor is OK most particulary if you dive with a fixed orifice, known dil and usual depth ( for you ), with some experience the "normal" PO2 is quite instinctively estimated, and you rather quickly notice an unusual reading. I do it from time to time and never felt in danger -two sensors is optimal -three sensors is perhaps not a good idea on mCCR because there is a risk to "think" like a simple stupid voting logic and to vote out the only good sensor.
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19th May 2007, 13:40	#4 (permalink)
Dave Sutton Diveshop of Horrors Current Rebreather/s: Sport Kiss MK 15.X rEvo Other CCR Azimuth Home Build Other Rebreather/s: Evolution Megalodon rEvo Other CCR Azimuth Home Build Join Date: Jun 2006 Location: Narragansett, Rhode Island and Hackettstown, New Jersey Posts: 2,907	Re: 1-cell vs 3-cell monitoring Duh....... Two minimum. Three lets you keep diving for the rest of the week if one craps out. Voting between them is easy: Flood with diluent and do basic math. One is unsafe. Yes, you can get away with it (I have), but it's really dumb. If you came aboard EXPLORER, a place where I encourage innovation and homebuilts, I would not allow you in the water with a single cell CCR of any sort. Take that for what it's worth, from a dedicated minimalist/alpinist with a really open mind. This is just about the only thing I would put my foot down over. Don't do it. Dave __________________ "Silent Diving with No Bubbles and No Politics".... www.nobubblediving.com
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