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Thread: Co2 sensor in breathing loop

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    RBW Member oamr_nagia is an unknown quantity at this point oamr_nagia's Avatar
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    Co2 sensor in breathing loop

    I had a random thought, Has anyone herd of anyone putting a analog Co2 sensor in the breathing loop of any rebreather.

    Now i know i am a noob to RBW and to rebreather diving ( i have yet to get trained but i do have a lot of time on OC ) but i cant find any info on a Co2 sensor installed in a breathing loop.
    The way i see it you could use it to check the health of your scrubber mid dive ( given i know you would never push your gear to the max ) but it is another parameter you can keep a eye on

    Any thoughts on the idea

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    Re: Co2 sensor in breathing loop

    Many people(most like all the CCR divers) thought about it, but the problem lies in the CO2 sensor technology available today. As far as I know most use infrared light absorption to measure the Co2 content. Their measuring properties are being affected by humidity and helium. Many companies have been working on a different technology that would eliminate this problem, but none has yet succeeded. I wouldn't be surpirsed to find out that the military has the required knowledge on hand?! VR technology has a working sensor available for the Sentinel CCR, but I don't know how accurate it is. Sentinel owners know it better. Just my two cents worth..

    Very Respectfully

    Roland Somodi

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    Re: Co2 sensor in breathing loop

    Quote Originally Posted by rolanddiver  View Original Post
    Many people(most like all the CCR divers) thought about it, but the problem lies in the CO2 sensor technology available today. As far as I know most use infrared light absorption to measure the Co2 content. Their measuring properties are being affected by humidity and helium. Many companies have been working on a different technology that would eliminate this problem, but none has yet succeeded. I wouldn't be surpirsed to find out that the military has the required knowledge on hand?! VR technology has a working sensor available for the Sentinel CCR, but I don't know how accurate it is. Sentinel owners know it better. Just my two cents worth..

    Very Respectfully

    Roland Somodi
    I think this is correct, VR have something and APD are working on it. You can also do a search and find some information about other rebreather manufacturers that are trying to make a unit with this technology.

    Another problem with sensing after the scrubber is that it only tells you about scrubber function and not about the divers-health. The latter (end-tidal PCO2 measurement) you can find out about in detail by goggling an article by Simon Mitchell called "Dummies Guide to CO2 - What is end tidal PCO2 and why is it important? ".

    Cheers
    Matt.

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    Re: Co2 sensor in breathing loop

    Quote Originally Posted by rolanddiver  View Original Post
    I wouldn't be surpirsed to find out that the military has the required knowledge on hand?!
    Rumor was that the Israeli military solved the problem, but they weren't sharing the technology. If true, I can't blame them.

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    Sorta New Member w ripley is a name known to all w ripley is a name known to all w ripley is a name known to all w ripley is a name known to all w ripley is a name known to all w ripley is a name known to all w ripley is a name known to all w ripley is a name known to all w ripley is a name known to all w ripley is a name known to all w ripley is a name known to all w ripley's Avatar
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    Re: Co2 sensor in breathing loop

    Here's one approach. Saw this at DEMA this year. Several people on Cave Diver's Forum are saying good things about them and supposedly the membrane on the sensor works. The sensor will screw into many existing RBs. The Hammerhead, for example, has a 4th sensor slot and is already hardwired for the electronics & HUD via the port on its head. I'm waiting to see the hardware come down in size A LOT + more dive time on the sensors.

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    Re: Co2 sensor in breathing loop

    The following is what I remember from Simon Mitchells excellent presentation at Eurotek 2010.

    For the most part it seems that the moisture issue has been solved.

    Now the arguments seem to be on where in the loop to place it. Down stream of the scrubber tells you the scrubber's performance, downstream of the diver should warn of retention issues, however it has to be very close to the mouth to avoid dilution with loop gas.

    Ideally we'd have 2 sensors at the divers mouth on both sides of the loop. So now I think it's a matter of fitting them in to the DSV/BOV unobtrusively.

    I've seen one demo version from Amphilogic.

    Also saw something with orange cabling that looked like it was an attempt to fit to the DSV but still a work in progress.

    I'm hoping that the next years will see viable models that would be retrofittable to the loop perhaps at the hose couplings to the DSV, with integrations in to existing models of upgradable computers like the Shearwater, Liquivison, DR-5 etc.

    Cheers

    Seb

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