Propane EFI part duece

[steve ravet]

I wrote a FAQ a long time ago about R-12, hydrocarbon blends, the EPA,
etc.  If you search Deja News you can probably turn it up.

Propane is similar in pressure/temp to R-22 (house refrigerant).  Too
high for automotive use.  What will replace R-12 is a 70/30 or so mix of
propane/iso-butane.  This is of course illegal according to EPA
regulations, at least in the context of using this mix to replace an
"ozone depleting" refrigerant.  If you want to convert your 134a system
to hydrocarbons no problem.  Except that some states have banned
flammable automotive refrigerants also, under any circumstances.  A news
show here in town actually blew up a car on TV during a report on
"dangerous flammable refrigerants".  I called and chatted with them
about responsible journalism.  I think journalism shool dropouts end up
as TV reporters.  The DOE commissioned a study on flammable refrigerants
in cars and determined that there was negligible danger in retrofits,
and (obviously) even less danger in systems designed with hydrocarbons
in mind, due in part to a "lack of credible ignition sources". 
Hydrocarbons are compatible with the rubber seals and oils used with
R-12 so other than the legal status they're a good choice.

There are non-flammable R-12 compatible choices also.  R-406a and some
variants were invented years ago, and held up in the mobile EPA SNAP
approval process (stationary approval was given quickly) until the 134a
switch was completed, despite the fact that it's better than R-12 or
134a.  I've been using 406a for years with no problems.  (satisfied
customer, I don't sell it).  Check out www.autofrost.com.  As I
mentioned, if Deja News still goes back that far, there was a lot of
discussion about this in the 93-96 timeframe.

sorry for the non-efi content...

--steve

"K.E. Towle" wrote:
> 
> >"Thermodynamic Properties of Refrigerants", as published by ASHRAE.
>  Propane is a _VERY_ good refrigerant, thermodynamically speaking.<
> 
> Hey, what I want out of this discussion is how I can flush out my R12
> system and replace it with propane. What would have to be changed in the
> system? How I'd love to thumb my nose at the massive government mandated
> taxes that have driven the cost of R12 into the stratosphere. I can't
> imagine a couple of pounds of propane up front would be that much more
> hazardous than a couple dozen gallons of fossil fuel in back.
> 
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-- 
Steve Ravet
steve.ravet at arm.com
ARM,Inc.
www.arm.com
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