Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ames!ncar!noao!asuvax!enuxha!kluksdah
From: kluksdah@enuxha.eas.asu.edu (Norman C. Kluksdahl)
Newsgroups: sci.electronics
Subject: Re: Repairing Intermittent Circuit Boards
Summary: Flourocarbons and Ozone
Message-ID: <23@enuxha.eas.asu.edu>
Date: 3 Feb 89 22:57:14 GMT
References: <2910@hound.UUCP> <1677@kodak.UUCP> <4495@umd5.umd.edu>
Organization: Arizona State Univ, Tempe
Lines: 35

In article <4495@umd5.umd.edu>, cgs@umd5.umd.edu (Chris Sylvain) writes:
> In article <1677@kodak.UUCP> ornitz@kodak.UUCP (barry ornitz) writes:
> ] The component "freeze" sprays are generally dichlorodifluoromethane, often
> ] called Freon-12 or Refrigerant-12;
> 
> As I learned from an atmospheric chemist (and from a short research paper
> I wrote), the reason R-12 (or CCl2F2) lasts so long in the atmosphere is that
> there is no chemical "handle" in the lower atmosphere that can break up
> the molecule. There are two notable refrigerants with nearly the same
> refrigerant effect as R-12, and very similar chemical non-reactivity:
> R-22 (CHClF2) and R-134A.
> 
> The difference is that R-22 is a hydrochlorofluorocarbon. The hydrogen atom
> gives nature a handle on the molecule, so its lifetime in the lower atmosphere
> is greatly reduced.
> 
There is a very good paper, for those of you who care, about the effects of
flourocarbons on the ozone layer, and the chemistry and atmospherics of
their interaction.  It may not be easy to find--it's in the Jan-Feb 1989
issue of American Scientist, published by Sigma Xi, by F. Sherwood Rowland.

My opinion, for what it's worth (and I realize that this may seemingly have
little to do with sci.electronics), is that we should all be conscious of
the 'coolant' products which we are using.  This is, however, sometimes
difficult, as locating 'thermal' chips requires spot cooling on the pc board.

If we can't avoid flourocarbons completely, let's at least minimize their use.

(And that is the extent of my environmentalist soap-boxing.)


Norman Kluksdahl              Arizona State University
            ..ncar!noao!asuvax!enuxha!kluksdah

standard disclaimer implied