This it too good- I'm going post it on the list.
TBill

Carl Ponder wrote:
> 
> TBill
> You recently wrote:
> > Um, the later, I think. BTW, can you mix the propane with the feon, or
> > do you have to evacuate the feon first?
> 
> In support of your position, I recently came across a letter as follows:
> 
> > This discussion was hashed out years ago on sci.energy.  Here are some
> > of the points:
> >
> > 1.  No one disputes that that hydrocarbon refrigerant is explosive when
> >     mixed with air in the proper proportions.
> >
> > 2.  However, it takes a gross leak in an air conditioning system to get
> >     enough hydrocarbon refrigerant into the air to get to an explosive
> >     mixture.
> >
> > 3.  Refrigerant leaks are normally very slow on air conditioning systems.
> >     These leaks are so slow that you won't build up an explosive mixture
> >     either inside the passenger compartment or a closed garage.
> >
> > 4.  You can get a fast leak if you are involved in an accident.  But
> >     even if you have a fast leak, you need to have a fairly optimum
> >     mixture of fuel and air to get an explosion.
> >
> > 5.  There is enought (flamable) oil in an A/C system that even
> >     a system with only R-12 can have a leak which will burn like a
> >     blow torch, producing chlorine gas in the process.
> >
> > 6.  If you are talking about a major accident, you need to keep in mind
> >     that you may have 100 lbs of flamable gasoline, 8 lbs of flamable
> >     engine oil, a few pounds of flamable brake fluid, some flamable clutch
> >     fluid, etc.  Cars are rolling bombs, even without any A/C.  A few pounds
> >     of flamable refrigerant may not be a significant additional hazard.
> >
> > 7.  If you do put hydrocarbon refrigerants into your A/C system, clearly
> >     label the system so that someone servicing it knows that hazard which
> >     may exist if the system is opened up (large leak).
> >
> > 8.  The propane/iso-butane mix is a better refrigerant than R-12, and will
> >     give better cooling.
> >
> > 9.  If you are not comfortable with it, don't do it.  But keep the the
> >     scare stories in perspective.
> >
> > 10. I believe that pure hydrocarbon refrigerant substitutes are not
> >     "approved" by EPA.  But there is no environmental problem with them.
> >     The EPA is responding to pressure from the automobile A/C servicing
> >     lobby, and imposing regulations outside of their proper area of
> >     concern.
> >
> > Donald Borowski    WA6OMI    Hewlett-Packard, Spokane Division
> 
> I personally subscribe to the conspiracy theory between Dow Chemical, The EPA,
>  and the Automakers.
> 
> Carl