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Subject: Fluorocarbons


From: Walter Henry <whenry>
Date: Sunday, October 6, 1991
The following appeared in sci.chem and is reposted her without the
knowledge or consent of the authors

    From: ghg [at] en__ecn__purdue__edu (George Goble)
    Subject: Ozone-safe propellants
    Date: 29 Sep 91
    Organization: Purdue University Engineering Computer Network

    In article <1991Sep25.191639.3388 [at] Csli__Stanford__EDU> chardros [at] Csli__Stanford__EDU
        (Doug Gibson) writes:
    >In <cwVR91w164w [at] tornado__welly__gen__nz> xanax [at] tornado__welly__gen__nz
    >    (Gerry Macridis) writes:

    >>What specific chemicals are currently substituted for
    >>chlorofluorohydrocarbons as propellants?
    >Actually, if I remember right, the chlorofluorohydrocarbons ARE the
    >substitutes for chlorofluorocarbons.  Seems they do much less damage

    I think you may mean "hydrochlorofluorocarbons" instead, or "HCFCs",
    which are just CFCs with one or more hydrogen atoms, thus causing
    them to break up before reaching the ozone layer.  I have seen
    chlorofluorohydrocarbons equated to "CFCs" also, since, CFCs/HCFCs
    begin as hydrocarbons, mainly "methane" (CH4), and "ethane" (C2H6),
    and are selectively chlorinated and fluorinated to become the
    desired product.

    The most common CFCs are R-11 and R-12 (Freon-11, Freon-12), also
    Freon-113 is also sometimes known as "Freon-TF" (mixed with small
    amount of Alcohols for solvent use). R-22 (Freon-22), is an HCFC,
    and it commonly used in window A/Cs, and central units has only 1/20
    the ozone depletion of R-12 (Freon-12), a CFC, used in Auto A/C, and
    Freezers & fridges.  The general public seems to call all
    refrigerants "Freon", which is incorrect, since Freon is a
    registered trademark of DuPont.  Actually, I think "Freon" is
    no longer made by DuPont (or in the near future), but Dupont buys
    "Genetron" >From Allied-Signal, and resells it is "Freon".  (they
    are all trade names for the same substances).

    HFC-134a would work as an ozone safe replacement for R-12
    (propellent), but it is $25/lb.  R-123 (an HCFC) was touted (and
    went on sale) as a 97% less ozone depleting replacement for
    Freon-11.. until they found that toxicity tests showed testical
    tumors on rats at 300ppm. DuPont is recalling the Freon-123 (maybe
    Suva-something??) from large centrifugal chillers and replacing it
    with ozone depleting Freon-11 after that. Lots of refrigeration
    jokes running around like "Did your balls fall off yet?" after
    installing R-123 equipment, etc.

    I think propane/butane/isobutane and mixtures thereof are used as
    propellants. They are flammable though.  I once made a refrigerant
    and ran my car on a mixture of isobutane/propane, to replace CFC-12,
    a couple of years back.  It worked fine.


                  Conservation DistList Instance 5:22
                  Distributed: Sunday, October 6, 1991
                        Message Id: cdl-5-22-005
Received on Sunday, 6 October, 1991

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