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Thread: mCCR or eCCR

  1. #11
    Nicholas Smith Abbo has a reputation beyond repute Abbo has a reputation beyond repute Abbo has a reputation beyond repute Abbo has a reputation beyond repute Abbo has a reputation beyond repute Abbo has a reputation beyond repute Abbo has a reputation beyond repute Abbo has a reputation beyond repute Abbo has a reputation beyond repute Abbo has a reputation beyond repute Abbo has a reputation beyond repute Abbo's Avatar
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    Re: mCCR or eCCR

    Fair point, Stuart. I'm probably more concerned about the electronics sending the loop wildly hyperoxic, though. After all, hypoxia surely comes from a sustained period of inattention, whereas an electronic failure can suddenly cause the computer to fill the loop with dangerous amounts of oxygen, and ox tox hits can be so sudden. I'm sure your answer will be "listen for the solenoid", but OC divers are pretty inured to noise!

  2. #12
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    Re: mCCR or eCCR

    I also use a lower set point but fly manually (on an Optima). It is good to have it for back up if nothing else.

    Sometimes, it is also convenient to say: "Okay computer, I will watch over you when you fire for my benefit on this special occasion since my hands are pretty busy right now."

  3. #13
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    Pelagian DCCCR

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    Re: mCCR or eCCR

    Quote Originally Posted by Mixaddict  View Original Post
    Stuart,

    I do the same thing, and it sure does make me angry when I find that I have not paid attention sufficiently, and the electronics kick in! It is certainly a wake up call when it happens!

    Regards,
    Randy
    Same here.....
    Every time the solenoid kicks in its a failure on my part.....

    /Rodge

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    New Member granso is an unknown quantity at this point granso's Avatar
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    Re: mCCR or eCCR

    OK, I don't know anything (almost) about rebreathers and that's why I am here an I read and ask. I still dive OC
    So, from what I understood, the main difference between ECCR and MCCR is the supply loop, I mean the settings are electronically controlledor by a mechanical mass flow regulator.
    What's the difference in numbers of operations between ECCR and MCCR during a dive?
    In case of electronics, how can I control what the unit is doing? I mean should I rely on electronics? Is there any sensor to read the PpO2?

    thank you
    SG

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    Re: mCCR or eCCR

    Granso,

    Can I suggest you try going to the AP website and reading the manual. Thats likely to answer a lot of your current and future questions.

    /Z

  6. #16
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    Re: mCCR or eCCR

    Quote Originally Posted by Abbo  View Original Post
    Fair point, Stuart. I'm probably more concerned about the electronics sending the loop wildly hyperoxic, though. After all, hypoxia surely comes from a sustained period of inattention, whereas an electronic failure can suddenly cause the computer to fill the loop with dangerous amounts of oxygen, and ox tox hits can be so sudden. I'm sure your answer will be "listen for the solenoid", but OC divers are pretty inured to noise!



    Hello Abbo, whether E or M CCR, you should always be monitoring your PO2 so whatever happens, you should be able to handle the situation in short order. Most units now have HUDs, making it easier to know your PO2 than ever before-it's in your face.

    Diving CCR is amazingly quiet. The solenoid is loud enough that you can't miss it, listening for it is part of my PO2 monitoring routine. When mine blocked up it sounded very different-sluggish, slower flow of gas out of the injector. I knew imediately what was happening.

    There are pros and cons to both M and E. And as others have pointed out, it's doesn't have to be either or. The shades of grey become apparent as you learn the level of diver involement required by each design. I prefer to keep things simple, but I also want a unit that can keep me alive when I need both my hands for something important-like pulling myself up a wall to keep from being blown down another 20 mtrs by a strong current. My unit-Prism-is a set point only controller, meaning all the electronics do is keep the SP, which is set during the predive. It's the simplest ECCR-on/off switch, HUD and a passive 2dry-and thus as close to the KISS concept as is possible with ECCR. Keep on asking questions and good luck. -Andy

  7. #17
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    Re: mCCR or eCCR

    I think some of the people here have hit upon some of the realities of the differences between philosophies, even though any eCCR (well, ok, most any) can be operated as a mCCR - its just more difficult.

    Reality is this - with a KISS-style CCR (constant-mass-flow set just below your resting metabolic demand) you KNOW that if you don't pay attention to it you WILL die. There is no ifs, ands, buts or maybes. Its a question of when, not if - there is no alarm, there is no automated "ripcord" on the parachute. You either use the big computer or croak - period.

    With an eCCR, one can become complacent. Operating an eCCR manually is more time consuming than a mCCR, because there is no constant mass flow. You must therefore adjust more frequently if you're going to operate manually. This becomes less demanding on your time the deeper you go, because there are more molecules of oxygen that make up a PPO2 "unit", yet your metabolic demand is measured in molecules, not PPO2.

    If you trust the electronics, that is when you're in trouble. Frankly, I don't know if I buy the "suddenly hyperoxic" scenario - at least not without warning. You CAN hear gas flow and it does take time for the PO2 to get dangerously high - not a long long time, but its not instant either.

    What I do buy is the "slowly hyperoxic" scenario due to bad sensors that you "trust", or due to some other systemic flaw that is not caught. Or, the computer goes haywire and locks up - it SAYS everything is ok (because the last screen it displayed was!) as the PO2 dwindles to zero...... oops!

    The record shows a radical disparity in death rates between mCCRs and eCCRs. All we have is speculation on the reasons, but I think this fits the pattern. So you have to ask yourself - can you remain vigilant if you know there's a "parachute", but it may not work? If the answer is "no" then a mCCR is probably safer for you, because there is no parachute on one. If the answer is "yes", then an eCCR can be operated safely by you.

    I don't believe there is a "pat answer" to this question...... you have to look inward at how you personally are wired.

  8. #18
    Nicholas Smith Abbo has a reputation beyond repute Abbo has a reputation beyond repute Abbo has a reputation beyond repute Abbo has a reputation beyond repute Abbo has a reputation beyond repute Abbo has a reputation beyond repute Abbo has a reputation beyond repute Abbo has a reputation beyond repute Abbo has a reputation beyond repute Abbo has a reputation beyond repute Abbo has a reputation beyond repute Abbo's Avatar
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    Megalodon

    Re: mCCR or eCCR

    The comments about flying eCCRs largely manually are well taken, but one final question: is there any evidence that anyone has been killed by an eCCR solenoid failing and flooding the loop with O2?

  9. #19
    RBW Member kiam will become famous soon enough kiam will become famous soon enough kiam will become famous soon enough kiam's Avatar
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    Re: mCCR or eCCR

    If you can, try a number of different rebreathers, ECCR and MCCR. My personal suggestion would be either the Classic KISS or the Copis Meg. Enjoy!

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