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Thread: physical risks of hydrogen?

  1. #11
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    Re: physical risks of hydrogen?

    Quote Originally Posted by Abbo  View Original Post
    The move to hydrogen seems to have been brought on largely because of the $ cost of Helium, but rebreathers don't waste much diluent and the $ is tanking. It was also caused because the US once had a near-monopoly on Helium, but that is no longer the case, as deposits are being exploited in the FSU.
    I though I read that hydrogen was preferred for HPNS problem reductions but I don't bother to track things like that as they are so far out of my sphere so I can't give you a refference...

  2. #12
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    Re: physical risks of hydrogen?

    Quote Originally Posted by Genesis  View Original Post
    At mixtures containing over 4% O2 hydrogen can rapidly combine with that oxygen to form water.

    (This is commonly called "an explosion" and is really bad if it happens in your breathing loop!)
    I get enough water in my loop as it is so I think I'll skip this one! :D

  3. #13
    Normal people worry me jaap is a name known to all jaap is a name known to all jaap is a name known to all jaap is a name known to all jaap is a name known to all jaap is a name known to all jaap is a name known to all jaap is a name known to all jaap is a name known to all jaap is a name known to all jaap is a name known to all jaap's Avatar
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    Re: physical risks of hydrogen?

    Quote Originally Posted by hirudin  View Original Post

    I read the Comex articles discussing the use of hydreliox and the physical effects the divers experienced on the dives, but it certainly doesn't seem like a good idea... and I don't like the idea of partially-hydrogenating my own body fat.

    Guess I'm just interested in a discussion on the use of hydrogen and it's longer term effects.... just for yuks.

    -Jesse-
    Hi

    Hydrogenation of unsaturated fats are usually processes that require somewhat elevated temperaures and a catalyst. So don't expect much to happen with the bodyfats of the hydrox/hydreliox-diver.

    Hydrogen-mixes have been used in experimental diving and even for some working dives for over 60 years, by many nations and corporations. So I'm quite sure they did think about this potential side effect.

    As a side note I think the rational for adding hydrogen into diving mixes have been a mix of the following:
    • Cost and avaliability. He was a strategic resource, like during WWII. So some could not get enough/afford a He-based deep diving program.
    • Low density, H2 is even better than He if you need to breath at extrem depths.
    • HPNS countermeasure, H2 is slightly narcotic so the idea is that a moderate narcosis level makes the diver less susceptible to HPNS
    Of course Hydrogen is probably completely useless unless you are going very deep. Given that I have never heard of any diving program combining any significant fraction of H2 with more than ~4% O2 (risk of explosion).

    PS
    If you want to think about really funky stuff, look around for info on "chemical deco". That is using like H2 for diving combined with an in vivo (inside the diver) catalyst that decomposes the accumulated gas into water cutting the deco. There is also som really far off talk about using nitrogen fixating bacteria to cut deco from nitrogen mixes...or the use of methane breathing mix and decocutting bacteria...
    Last edited by jaap; 19th November 2007 at 13:51.

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    Re: physical risks of hydrogen?

    Quote Originally Posted by Abbo  View Original Post
    There's some interesting reading on "Hydrogen as a breathing gas" by RW Braur at
    Rubicon Research Repository: Item 123456789/4862
    Thanks Abbo! Always nice to see the repository being used! The full reference for the workshop is:

    Brauer RW (ed). Hydrogen as a Diving Gas. 33rd Undersea and Hyperbaric Medical SocietyWorkshop. UHMS Publication Number 69(WS-HYD)3-1-87. Bethesda: Undersea and HyperbaricMedical Society; 1985; 336 pages. RRR ID: 4862

    Note: The file is pretty big.

    Quote Originally Posted by jaap  View Original Post
    If you want to think about really funky stuff, look around for info on "chemical deco". That is using like H2 for diving combined with an in vivo (inside the diver) catalyst that decomposes the accumulated gas into water cutting the deco. There is also som really far off talk about using nitrogen fixating bacteria to cut deco from nitrogen mixes...or the use of methane breathing mix and decocutting bacteria...
    And... Most of that work was done at NMRI by Kayar and Fahlman.

    Decompression sickness risk reduced by native intestinal flora in pigs after H2 dives.
    Kayar and Fahlman. Undersea Hyperb Med. 2001 Summer;28(2):89-97.
    RRR ID: 2373

    MODULATION OF DECOMPRESSION SICKNESS RISK IN PIGS BY CAFFEINE ADMINISTRATION DURING H2 BIOCHEMICAL DECOMPRESSION.
    Kayar et. al. 2001 (UHMS abstract)
    RRR ID: 1027

    DECOMPRESSION SICKNESS RISK CORRELATED WITH ACTIVITY OF H2-METABOLIZING MICROBES INJECTED IN PIGS PRIOR TO DIVES IN H2.
    Fahlman et. al. 1999 (UHMS abstract)
    RRR ID: 787

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