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Thread: 2-cassette scrubber system for the Meg

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    New Member Bazza has a spectacular aura about Bazza has a spectacular aura about Bazza has a spectacular aura about Bazza has a spectacular aura about Bazza has a spectacular aura about Bazza's Avatar
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    Re: 2-cassette scrubber system for the Meg

    Quote Originally Posted by jlovold  View Original Post
    which increases the amount of usable fresh sorb in the cassette .
    This is not correct you still have the same amount of sorb in the cannisters so no "increase" in usable sorb.

    regards Baz

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    RBW Member rjack will become famous soon enough rjack will become famous soon enough rjack will become famous soon enough rjack's Avatar
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    Re: 2-cassette scrubber system for the Meg

    Quote Originally Posted by KISSit!  View Original Post
    Whadda ya mean? this is the home build forum after all, and its more fun to design and build yourself!
    Execution is great
    Whether it accomplishes anything useful is debatable.

  3. #13
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    Re: 2-cassette scrubber system for the Meg

    Agreed that its functionality is limited without a monitoring system.

    But it still means you can provide a large buffer zone of known fresh sorb and still completely wring out the last use of the first cartridge. And there's nothing wrong with that.

  4. #14
    RBW Member jlovold is a jewel in the rough jlovold is a jewel in the rough jlovold is a jewel in the rough jlovold is a jewel in the rough jlovold is a jewel in the rough jlovold is a jewel in the rough jlovold is a jewel in the rough jlovold's Avatar
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    Re: 2-cassette scrubber system for the Meg

    Quote Originally Posted by Bazza  View Original Post
    This is not correct you still have the same amount of sorb in the cannisters so no "increase" in usable sorb.

    regards Baz
    It is not an increase in actual sorb. But a more efficient use of the available sorb, because the reaction-zone is conical. When you turn the flow, a larger amount of unused sorb will be in the potential reaction-zone.

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    Re: 2-cassette scrubber system for the Meg

    Quote Originally Posted by rjack  View Original Post
    Except that you have no idea how much of 2nd downstream section has been used. And sorb in an axial scrubber is not used up in uniform front.
    By having a large diameter scrubber, and a known amount of sorb, you should have a pretty good idea of how much of the scrubber is spent.

    Also, by having two reaction-fronts, unless you have overbreathed it, the reaction front on the second cassette should be wide and shallow. Which is why you could turn it around and use it on the exhale-side afterwards.

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    Re: 2-cassette scrubber system for the Meg

    Quote Originally Posted by jlovold  View Original Post
    By having a large diameter scrubber, and a known amount of sorb, you should have a pretty good idea of how much of the scrubber is spent.

    Also, by having two reaction-fronts, unless you have overbreathed it, the reaction front on the second cassette should be wide and shallow. Which is why you could turn it around and use it on the exhale-side afterwards.


    The reaction front in an axial scrubber is actually an inverted cone.
    http://johnclarkeonline.com/2011/10/...isters-part-2/

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    Re: 2-cassette scrubber system for the Meg

    Quote Originally Posted by rjack  View Original Post
    The reaction front in an axial scrubber is actually an inverted cone.
    http://johnclarkeonline.com/2011/10/...isters-part-2/
    Really?

    What did I just say?

    On the inhale cassette, unless you have done it completely wrong, there should only be trace amounts of a reaction-zone.
    If you pay attention to the time used, the amount of sorb, and the workload you have had during the dive, It is very safe to use it as the exhale scrubber afterwards.

  8. #18
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    Re: 2-cassette scrubber system for the Meg

    Yep you are spot on the heat source could be some distance below or behind the circumference break through area of the reverse cone. This is why the temp stick is only a guide. The degree of usefulness depends on the design of the scrubber stack.


    Sent from my Nexus 5X using Tapatalk

  9. #19
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    Re: 2-cassette scrubber system for the Meg

    I dont quite understand why inverting the flow once the inhale scrubber becomes the exhale scrubber is important.
    But I do see the benefit of a "mixing chamber" between the scrubbers. This design does not seem to have this as far as I can tell.
    The mixing chamber will stop a break through from the 1st scrubber concentrating CO2 at the same point on the next scrubber.

  10. #20
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    Re: 2-cassette scrubber system for the Meg

    Quote Originally Posted by Packhorse  View Original Post
    I dont quite understand why inverting the flow once the inhale scrubber becomes the exhale scrubber is important.
    But I do see the benefit of a "mixing chamber" between the scrubbers. This design does not seem to have this as far as I can tell.
    The mixing chamber will stop a break through from the 1st scrubber concentrating CO2 at the same point on the next scrubber.
    The location of a breakthrough should always occur at the point of lowest delta pressure in the stack/stacks.

    Michael

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