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  1. #11


    Let's pretend like those gills did work and didn't require a scooter battery for 15min of runtime and this wasn't just some "cool artsy rendering." It'd still be depth-limited to 20ft.

  2. #12


    Quote Originally Posted by chrpai View Post
    I'm not a CCR diver but I do know that oxygen consumption (metabolism) is not effected by depth and the entire o2 contents of that .5 scfm is not consumed. Some of it is exhaled.

    A quick google search suggests that actual o2 consumption is more around 1 - 1.5 lpm of O2. Feel free to redo your calculations based on that as I didn't really follow the rest of the math.
    You're right, my bad. I'm not a CCR diver either so I screwed that up. Divide or multiply the rest of the numbers by about two, and it should be close. So it's still over a gallon of water per second that you need to run through the gills, assuming perfect extraction of all oxygen.

  3. #13


    1 gallon per minute seems reasonable given the surface area. You just have to keep in constant swimming motion or you die. No big deal

    Sent from my SM-G930V using Tapatalk

  4. #14


    O2 consumption may not increase, but meeting O2 demands is only 1 function of the lungs - you also need sufficient air movement to allow for elimination of CO2. So in addition to extracting O2, it will need to extract a sufficient volume of gas to allow the lungs to expand at depth, and that WILL be depth dependent. The SAC rate corrected for depth is still appropriate for determining the volume of gas needed for normal respiration.

    The O2 content of that generated gas can decrease with depth, as the pO2 of the extracted oxygen will increase at depth. If the relative volume of oxygen delivered decreases with depth, it's possible that this could be used at any depth. It certainly won't deliver 100% oxygen. Of course, that's also part of the problem.

    In addition to oxygen being dissolved in water, there are a lot of other gasses present - and in a cave environment, that includes gasses like hydrogen sulfide. All ground water sources are important sinks of CO2, as well. I have no idea how they would control for what is extracted and what isn't.

    Also, since oxygen content of water can be variable, there's be no guarantees (even if it did work) that this wouldn't extract too much or too little for any given depth...and even if it had some sort of monitor, I don't know what you could do with that information other than knowing you were in trouble....

  5. #15
    Administrator Forum Admin
    Join Date
    Oct 2000


    Quote Originally Posted by IowaCaveDiver View Post
    ...You just have to keep in constant swimming motion or you die. No big deal
    Just like a shark

    Forrest Wilson (with 2 Rs)
    Any opinions are personal.
    Sump Divers

  6. #16


    Visions of Waterworld with Kevin Costner come to mind..

  7. #17


    So if you were diving at ginnie, you'd feel great swimming in, but if you drifted out you would likely pass out and drown.

  8. #18
    Special Forum Member
    Join Date
    Dec 2006
    Southport (Panama City), FL


    Quote Originally Posted by FW View Post
    That reminds me of a novel on the same subject. It was called "The Caves of Karst" by Lee Hoffman 1969. It talked about rebreathers, and cave divers with gills.
    I LOVE that book! I want fireflies!!

    I Semper Fi, Cameron David Smith, my son, my hero. 11/9/1989 - 11/13/2010

    Never forget, we were all beginners once. Allain Burrese

    My name is Shirley Kasser Creech and I approve this message. Well, at least one of me does, anyway. Maybe. Fire. Sharp things. Squirrel!


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