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Thread: Hydrophobic membrane scrubbers?

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    RBW Member Danseur is an unknown quantity at this point Danseur's Avatar
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    Hydrophobic membrane scrubbers?

    This question has troubled me for years, so I'll finally ask at the risk of sounding stupid:

    Why don't we see these everywhere?

    Cis-Lunar proved it, so why isn't it standard like seat belts and airbags +20yrs later?

  2. #2
    Reads fine print (mostly) Skipbreather has a brilliant future Skipbreather has a brilliant future Skipbreather has a brilliant future Skipbreather has a brilliant future Skipbreather has a brilliant future Skipbreather has a brilliant future Skipbreather has a brilliant future Skipbreather has a brilliant future Skipbreather has a brilliant future Skipbreather has a brilliant future Skipbreather has a brilliant future Skipbreather's Avatar
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    Re: Hydrophobic membrane scrubbers?

    Nothing's free. The cost is increased WOB and, well, actual cost. Cis paid that cost in order to gain the ability to change scrubbers underwater.

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    RBW Member theJonas is an unknown quantity at this point theJonas's Avatar
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    Re: Hydrophobic membrane scrubbers?

    Quote Originally Posted by Skipbreather  View Original Post
    Nothing's free. The cost is increased WOB and, well, actual cost. Cis paid that cost in order to gain the ability to change scrubbers underwater.
    Could you replace the scrubber in the middle of a dive on that one?

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    RBW Member whynot? will become famous soon enough whynot? will become famous soon enough whynot? will become famous soon enough whynot? will become famous soon enough whynot?'s Avatar
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    Re: Hydrophobic membrane scrubbers?

    Sandy cut a few for me, he knows the micropore size etc. I gave him a template for my 15.5 scrubber (there are 2 sizes for the top and bottom of the scrubber), he made an exact match! He's an amazing guy and has done some really neat things for the 15 community here. Reach out to him if you are interested.

  5. #5
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    HAMMERHEAD!

    Re: Hydrophobic membrane scrubbers?

    Another factor is the cost and complexity of the hydrophobic membrane, as well as the tremendous amount of labor required to assemble a Cis Lunar scrubber properly.

    We have all the components of the Cis Lunar scrubbers (since we still repair the Mark 5P as well as the newer Poseidon Mark VI and Se7en units) - and we actually looked into assembling more of them back in 2005 since they fit into standard Megs, and were a popular accessory of Meg owners (if they could find one). The cost of building them was super prohibitive, and the material (a tri-laminate from Millipore) was not available as an off-the-shelf item.

    When Bill Stone invented the Mark 5 (along with Nigel Jones), there were SO many amazing features of the system, it's hard to contemplate just how much engineering went into every single part of it.

    Unfortunately, that made them really expensive (I think they sold for $17k when new). The scrubber was revolutionary, as were many other features of that system. This puts the Mark 5 in the same category as the Mark 15/15.5 series. You just couldn't afford to actually make those rebreathers today and sell them in such a competitive market, unless you had a lot of money, and a lot of time to wait for your ROI.

    Another thing: When you look at Scrubbers - you have the Prism 2 Scrubber at the most basic level - it's really a Viper scrubber from Fullerton/Sherwood (who themselves got it from a Filter company, of all things), all the way up to the Meg and Hammerhead scrubber, which are more complex and use dissimilar materials like stainless steel and plastic, all the way up to the Cis Lunar scrubber which was the most complex of all.

    But the Viper/Prism 2 scrubber works just fine - so it's hard to imagine making one more complex in today's age. The only reason other companies don't replicate the Viper scrubber is because the Injection Mold costs would be huge - so it's actually cheaper in the long run to assemble one from machined parts (like everybody else does today).

    I haven't talked about the Micropore scrubber because they are in a class all by themselves. I was at Hydrospace (the US Navy's testing site next to NEDU) testing some new material from Micropore just a few months ago, and it is phenomenal. Imagine something roughly the side of 2 decks of playing cards absorbing 1 hour of CO2 at 3 lpm. Pretty cool stuff...

    Kevin Juergensen
    Juergensen Marine, Inc.

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    RBW Member Lancer4545 is a splendid one to behold Lancer4545 is a splendid one to behold Lancer4545 is a splendid one to behold Lancer4545 is a splendid one to behold Lancer4545 is a splendid one to behold Lancer4545 is a splendid one to behold Lancer4545 is a splendid one to behold Lancer4545 is a splendid one to behold Lancer4545 is a splendid one to behold Lancer4545 is a splendid one to behold Lancer4545 is a splendid one to behold Lancer4545's Avatar
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    Re: Hydrophobic membrane scrubbers?

    I was told Bill Stone and a few others were investigating the of using Lithium Hydroxide in the Cis to extend scrubber durations even further than what they were getting with Sodium Hydroxide based scrubber mediums.

    Lithium Hydroxide is extremely volatile and unstable when mixed with even the slightest quantity of water hence the hydrophobic membrane.

    I've been told from those who have experimented with it that every granule of dust that contacts your skin makes a burning sensation. Not surprising is was not pursued any further.

  7. #7
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    Re: Hydrophobic membrane scrubbers?

    I have a Porex membrane on the exhale side of my scrubber. It definitely helps keep water away from the sorb in the unlikely event of a major flood. However the downside is that the water produced during the scrubber reaction is trapped in the scrubber, rather than pool up at the bottom of the can. This isn't much, but I do see more caked up sorb with the membrane than without.

    Like everything - sacrifices to be made.

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    RBW Member Danseur is an unknown quantity at this point Danseur's Avatar
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    Re: Hydrophobic membrane scrubbers?

    So looking at say a Spirit or rEvo who don't handle flooding/moisture well, wouldn't this be the right use?

    When you end up with that caked sorb, does it just smash the WOV?

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    Re: Hydrophobic membrane scrubbers?

    well, a few tablespoons of water from the scrubber reaction will make a cake ball about the size of a golf ball which should hardly impact the WOB. A slug of water from a leak could be much more. This is what needs to be weighed when deciding.

    Personally, I have experienced catastrophic leaks that required bailing out, so am sensitized to leak tolerance and leak management capability. In my opinion and my personal diving, I thik its important to have the means to manage a leak adn a membrane helps this on the unit I dive.

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