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  1. #1
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    Default Manual or E-CCR for first time CCR diver

    I'm slowly paying more attention to info about rebreathers and reading on my own because in the future my wife will likely need to go to a rebreather for her research. That means I will probably follow so that we both take the step together. I'm way off from even considering a specific unit or taking the plunge, but some questions have come up in my reading.

    Some people are hardcore on the side that your first rebreather should be a manual unit, others say it doesn't matter, and some sit in the middle and prefer an e-ccr with mav's to allow it to be run as a manual (I guess that would be a hybrid). I'm also seeing that specifically for cave diving (and especially scootering in a cave), many prefer an electronic unit so that you're not continually hitting the mav button.

    I haven't really seen anyone ever express an opinion here, and since we'd be doing the majority of our rb dives in caves (after appropriate training), I thought this would be the place to ask.

    (My rb knowledge is still very basic, so if anything I said above doesn't make sense, I apologize).


  2. #2
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    Default

    i started with e-ccr because thats what the unit i wanted has. However, during training, i had to run it manually (with a lower SP parachute). There's dives ill dive manual, others let it run.


  3. #3
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    Default

    Quote Originally Posted by patpicos View Post
    i had to run it manually (with a lower SP parachute)
    Does the lower setpoint cause the unit to fire eventhough it's being run manually to keep you from dropping to too low of a pO2


  4. #4

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    Quote Originally Posted by rddvet View Post
    Does the lower setpoint cause the unit to fire eventhough it's being run manually to keep you from dropping to too low of a pO2
    Yes.

    Jason Gulley

  5. #5
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    Quote Originally Posted by jason View Post
    Yes.
    I guess I never thought about that. I always thought of "manual" as shutting off the solenoid or adv completely.


    Sent from my iPhone using Tapatalk


  6. #6

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    Quote Originally Posted by rddvet View Post
    I'm slowly paying more attention to info about rebreathers and reading on my own because in the future my wife will likely need to go to a rebreather for her research. That means I will probably follow so that we both take the step together. I'm way off from even considering a specific unit or taking the plunge, but some questions have come up in my reading.

    Some people are hardcore on the side that your first rebreather should be a manual unit, others say it doesn't matter, and some sit in the middle and prefer an e-ccr with mav's to allow it to be run as a manual (I guess that would be a hybrid). I'm also seeing that specifically for cave diving (and especially scootering in a cave), many prefer an electronic unit so that you're not continually hitting the mav button.

    I haven't really seen anyone ever express an opinion here, and since we'd be doing the majority of our rb dives in caves (after appropriate training), I thought this would be the place to ask.

    (My rb knowledge is still very basic, so if anything I said above doesn't make sense, I apologize).
    I know some people use mCCRs for research - but I personally think it is way easier to do research on an eCCR. There is less task loading associated with maintaining pO2.

    Jason Gulley

  7. #7

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    Quote Originally Posted by rddvet View Post
    Does the lower setpoint cause the unit to fire eventhough it's being run manually to keep you from dropping to too low of a pO2
    no. If you run an e-ccr in parachute mode as most do in a cave because of the ups and downs you actually are doing a lot more manual input than you would with an mccr. Good instructors will make you run it in manual mode for almost the entirety of the class so you'll get lots of button practice.
    The mccr's have a continuous flow of O2 that is supposed to match your resting metabolic rate so you are only adding the delta between that and your actual consumption. On an e-ccr in parachute mode, the solenoid does nothing until you hit that threshold so you have to manually add all of the oxygen.
    hccr's are e-ccr's that have some sort of continuous flow added to them, either a needle valve or CMF. All e-ccrs can be converted to h-ccr with a change in the O2 MAV.

    I think the more important bit is find a unit that works best for you and not worry about m vs. e. I think that will probably rattle out with e winning due to your wifes research. One less thing to worry about if you have your hands full with something. Doesn't excuse not monitoring it, but if you are using both hands for some sort of task, it's nice to have the unit run in cruise control.


  8. #8
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    Default

    Quote Originally Posted by rddvet View Post
    ... some sit in the middle and prefer an e-ccr with mav's to allow it to be run as a manual (I guess that would be a hybrid).
    Don't all eCCRs have a manual add valve?


  9. #9

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    As I was trained the manual running of the rb is meant to instill the habit of knowing your PPO at all times. So as a new RB diver it only makes sense to run the unit manually for a long period of time to get the habit of monitoring and controlling the O2 injection. I personally allow the electronics do their thing and I constantly monitor the ppo and act as the parachute should the electronics fail. Many do the reverse by controlling the partial pressure and let the electronics be the parachute.
    All tech RBs have manual add valves, hybrids have both a leaky valve and electronic controlled solenoid and a manual RB has a leaky valve and ppo monitoring only.

    Gabe


  10. #10
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    Default

    Quote Originally Posted by bent View Post
    Don't all eCCRs have a manual add valve?
    Not sure. Thats why I'm asking questions. I would assume for safety but thats part of all the things I'm trying to put together to understand.


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