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O2 consumption Question- CCR divers ???

Discussion in 'Research and Development' started by turnburglar, Oct 28, 2016.

  1. turnburglar

    turnburglar Angel Fish

    Hey Diver's did some googling trying to answer my own question and wouldn't mind having the board double check my work:

    1kg silver oxide absorbs 0.15 kg of CO2

    Average person makes 0.5 - 0.6 grams of Co2 per minute = 3 grams Silver oxide per minute

    1kg silver oxide should scrub for = 333 minutes (5.5 hours)

    Did I get this right?
  2. RainPilot

    RainPilot OC/CCR Instructor Trainer Staff Member ScubaBoard Supporter

    # of Dives: I just don't log dives
    Location: UAE
    Yeeeessssss but.....

    You will have breakthrough before that. As the scrubber material is used up on contact with CO2, you will have a reaction front moving through the scrubber in the direction of flow. At some point there will be a layer of unused scrubber remaining which will allow CO2 through it due to variations in the grain alignment. One can reduce this amount by channeling the flow through a narrow portion but then work of breathing (WOB) increases.

    Also, the CO2 production varies HUGELY with activity and also inter-individual. That average is the centre of a very flat curve.

    The WOB issue is addressed in space applications by using pumps and fans to force recycling through the system. This also pretty much eliminates dead space issues thus reducing CO2 retention.

    Are you looking at man-portable systems here? The weight of these systems gets pretty high pretty fast, in diving we have buoyancy to assist. That being said, there is no need to carry a diluent system as you can utilise the ambient air through a "suitable system of levers and linkages".

    Ive done some work in a previous life on individual life-support / environmental control systems in an aviation environment, Im sure a lot of the design criteria carry over. You are welcome to PM me if you have anything you want to check up / bounce ideas off.

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