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Thread: Liberty cell validation

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    RBW Member abscuba is an unknown quantity at this point abscuba's Avatar
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    Liberty cell validation

    This is just pure curiosity. I am curious as to how the Liberty CCR uses the helium sensors to validate the O2 cells. I understand the math as to I know the ratio in my dil so I can read the HE and see what the O2 is. How does the system judge from there? Which has priority the O2 or the HE if there is a difference in readings. What happens if you have a break through and now have CO2 in the system your HE system will be telling you the O2 cells are reading low when they are correct due to the introduction of an unknown about of CO2. Im sure there is a fail safe for all of this, really just curious.

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    RBW Master Plumber lof is a glorious beacon of light lof is a glorious beacon of light lof is a glorious beacon of light lof is a glorious beacon of light lof is a glorious beacon of light lof is a glorious beacon of light lof is a glorious beacon of light lof is a glorious beacon of light lof is a glorious beacon of light lof is a glorious beacon of light lof is a glorious beacon of light lof's Avatar
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    Meg,Prizm,RB80,LARV,MK15,HomeB

    Re: Liberty cell validation

    There is no galvanic O2 cell validation in Liberty at this time.
    There is an option to use He sensors to measure PPO2 if none of the O2 cells are operating (or are disabled).
    If you have CO2 in the system then you have much bigger problem than slightly inaccurate PPO2 measurement.
    The galvanic O2 cell validation is in the implementation stage at this time.

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    RBW Member abscuba is an unknown quantity at this point abscuba's Avatar
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    Re: Liberty cell validation

    Are the future upgrade plans to use voting logic in the system or another type of validation?

  4. #4
    RBW Master Plumber lof is a glorious beacon of light lof is a glorious beacon of light lof is a glorious beacon of light lof is a glorious beacon of light lof is a glorious beacon of light lof is a glorious beacon of light lof is a glorious beacon of light lof is a glorious beacon of light lof is a glorious beacon of light lof is a glorious beacon of light lof is a glorious beacon of light lof's Avatar
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    Meg,Prizm,RB80,LARV,MK15,HomeB

    Re: Liberty cell validation

    The plans are for validation of the galvanic O2 cells by the He sensors. There is no plan for voting logic between the two at this point.

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    RBW Member serpentara is an unknown quantity at this point serpentara's Avatar
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    Re: Liberty cell validation

    So how does helium validation work in an environment with Nitrogen? I mean you could use the % of helium in the gas to determine oxygen if you were only breathing heliox as a diluent.

    But if you are using trimix, the nitrogen and helium ongasses and offgasses at different rates. If you have been sitting doing deco for a while how does it account for the % of nitrogen that is in the loop? You cant just assume that the helium/nitrogen ratio in the loop is the same as the diluent ratio, right?

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    Re: Liberty cell validation

    Quote Originally Posted by serpentara  View Original Post
    So how does helium validation work in an environment with Nitrogen? I mean you could use the % of helium in the gas to determine oxygen if you were only breathing heliox as a diluent.

    But if you are using trimix, the nitrogen and helium ongasses and offgasses at different rates. If you have been sitting doing deco for a while how does it account for the % of nitrogen that is in the loop? You cant just assume that the helium/nitrogen ratio in the loop is the same as the diluent ratio, right?
    I'm pretty sure that the error is fairly small and is covered by "plan for O2 exposure at 0.05bar above set point and plan deco for 0.05 below setpoint" that we were taught on Mod 1.
    This is not a primary means of sensing your PPO2, just a sanity check and "everything else has failed, get me home" mode

  7. #7
    RBW Master Plumber lof is a glorious beacon of light lof is a glorious beacon of light lof is a glorious beacon of light lof is a glorious beacon of light lof is a glorious beacon of light lof is a glorious beacon of light lof is a glorious beacon of light lof is a glorious beacon of light lof is a glorious beacon of light lof is a glorious beacon of light lof is a glorious beacon of light lof's Avatar
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    Re: Liberty cell validation

    ^^^ correct.
    This is to be only used in the emergency to get you out of trouble.

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