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The misunderstood mCCR explained

Discussion in 'Rebreather Diving' started by Divetech Cayman, Jun 29, 2020.

  1. rjack321

    rjack321 ScubaBoard Supporter ScubaBoard Supporter

    # of Dives: 1,000 - 2,499
    Location: Port Orchard, WA
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    You all are mixing constant moles and variable volume with every other post and trying yourself in knots over it.

    Moles is introductory high school chemistry so I think that qualifies as "lay person" language - but perhaps not
     
    nadwidny and grantctobin like this.
  2. JMBL

    JMBL Solo Diver

    # of Dives: 1,000 - 2,499
    Location: France
    587
    253
    63
    Thank you for that clear and extensive comparison. I've been collecting data about rebreathers for a while and made my choice a few weeks ago : mCCR. Your work just confirms my choice. I'll be doing my training in July. Be glad to read more of your works.
     
  3. rddvet

    rddvet DIR Practitioner

    # of Dives: 50 - 99
    Location: Florida
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    moles were basic high school science for me, but you would be surprised how many people have never had any exposure to chemistry in hs or college. My view is skewed because I went to a private high school with much better instructors than most public schools. My wife teaches science at a university and you would be shocked at how many kids got very limited basic science exposure in hs. From what I’m seeing moles is definitely not in most people’s hs science background. Kinda scary.
     
  4. Superlyte27

    Superlyte27 Cave Instructor

    # of Dives: 5,000 - ∞
    Location: Florida
    3,859
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    I dove an mccr revo for a couple of years before I dove an HCCR revo for another couple of years.

    On both of those units, what was the ip set at @Dsix36 knows. It was a fixed ip. At 20' or 200' it was still pumping out 140psi. No big deal. But at 300', what was the reg pumping out? If I hit the MAV, how long did I hold it down for? Trick question, because it wouldn't add anything at 300' no matter how long I held it.
     
  5. 1c3d1v3r

    1c3d1v3r Rebreather Pilot

    # of Dives: 500 - 999
    Location: FInland
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    mCCR can have a leaky valve with fixed IP 1st stage. Or a needle or only a manual add valve.

    The false statements also caught my attension: "As we descend in the water column, diving physics increases our partial pressure of the oxygen, which means we need to add less oxygen into the loop."

    "After all, when your depths approach 100 meters, you need so little oxygen to sustain you."
     

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