Refrigerant and rebuilding AC (In defence of Durocool)

[santoli9 at cox.net]

You might find George Goble's take on this interesting. The full text is at http://www.yarchive.net/ac/politics.html
I've extracted a bit here:

There is some flammability risk for running pure hydrocarbons
(propane/butane, etc) in automotive A/C.. but it is pretty small.
OZ-12 (propane/isobutane) was installed in 50,000 cars with no
fire/safety problems reported.. until somebody "rigged" a controlled
demo, where 3 cans of it were released (took several tries) in a sealed
car passenger compartment, and recirulated until the correct fuel/air
mix was obtained.. and BOOM.. it did blow up.  Film at 11.. went to
CNN, etc.. which pretty much got it banned.  Using the fear of fire
in a non scientific manner to fear-monger the public.. Remember the
Hindenburg, the Pinto, The side mounted Pickup truck gas tanks, etc..
(remember the rocket engine ignitors?? on the truck blowing up?)

The A/C only holds 1.5lbs or so of propane/isobutane.  The gas tank
holds over 100lbs of gasoline.  Oil, brake fluid, transmission fluid,
power steering fluid, are all EXTREMELY FLAMMABLE/EXPLOSIVE when they
drip on hot enging/exhaust components. Hydrocarbons have to be at a fuel/air
ratio of roughly between 2% - 8% by volume in air in order to ignite.

In a hose break/leak, propane/butane dissipate rapidly, gasoline
hangs around, fuming, waiting for an ignition source.
R-12 systems contain approx 10-15% by volume of mineral oil, which
is dissolved in the refrigerant.  A line rupture creates in "oil fog"
which can be quite explosive.  A jet of R-12/oil mist leaking can be
ignited (I have a pix) and does sustain fire (looked like a flame-thrower).
That is why "those in charge" are VERY CAREFUL to specify flammability
specs WITHOUT the oil present, rather that what is really found in
a car A/C.  When you include the compressor oil, all the refrigerants burn.

Also, many common "tire inflator/sealer kits" use propane
and butane, and it is mixed with AIR UNDER PRESSURE in a TIRE.. and
this IS A BOMB by definition.  How come nobody raises much ruckus over
tire inflators, R-12 and oil burning, etc.  Those things do not have
the power to prevent the sale of millions of "extra" new cars like the
alternative refrigerants do (when the R-12 is gone). R-134a does become
flammable at just above atmospheric pressure (5 PSI).  There have been
reports of R-134a explosions in refrigerant lines/compressors.. Workers
unsoldering lines (had air/R-134a in them), after letting out the
refrigerant, built up a small positive pressure, or the burning of
the oil at the joint raised the local pressure above 5 PSI, and blam.
Go figure for yourself.