Recently there have been warnings on the GMCnet against the use of Durac=
ool primarily because of its flammability I posted a lot of informati=
on on this about 12 years ago. I felt it might again be good to examine th=
e reported track record of hydrocarbon refrigerants. This is what I sa=
id back then: Major conversion of car air conditioners from fluorocarb=
on to hydrocarbon refrigerant commenced in the USA in Idaho during 1992. =
I have been looking on the Internet for statistics and find that today (bac=
k in 2004) over 10 million car air conditioners worldwide have been convert=
ed, about half of these in North America, and over 30 million user years ha=
ve accumulated. Almost all of these have been drop-in conversions usually=
costing less than US$50. Indonesia, Korea, Philippines, China, Canada, A=
ustralia, Japan and other countries also have many systems with drop-in HC =
charges. In spite of this, there have been no reported fires, explosions=
or injuries to occupants caused by the flammability of hydrocarbon refrig=
erant in car air conditioners. Many cars with hydrocarbon refrigerant have=
had frontal collisions which punctured the condenser. Arthur D. Little, =
the well known consulting firm, estimated the frequency of the refrigerant=
catching fire from this common accident as once in ten thousand user years=
, so over 3,000 such fires should have occurred worldwide; if this had ha=
ppened it would have been big news and widely reported. But even so, no su=
ch fires have been reported. There are reports of such accidents with the =
refrigerant not catching fire. HC refrigerants have a condenser pressur=
e 10% lower than HFC-134a, making catastrophic leaks many times less frequ=
ent. HC REFRIGERANT IS ONLY FLAMMABLE BETWEEN 2.2 AND 9.6% VOLUME CONCENTR=
ATION IN AIR. It is non-flammable inside the refrigerant circuit where the=
concentration is always above 10%. HC refrigerants have a high leak and =
low flame velocity so an ignited leak tends to blow itself out. HC refrige=
rants have a lower density so the charged mass is only one fourth of HFC =
134a. When this small charge leaks from the evaporator into the passenger =
cabin, air leaks keep it non-flammable by preventing the concentration fro=
m exceeding 2%. HC refrigerants also have an odorant added to help preven=
t accidents. Has any of the GMCnetters actually seen or even heard of =
an actual fire? I feel it is a matter of personal choice as to one's a=
version to risk. 1 in 50 million might be acceptable odds to some but migh=
t be unacceptable to others. I personally feel that 0.00000002 is sufficie=
ntly close to zero. So, the benefits of using HC refrigeration in my GMC f=
ar outweigh any fire risk in my mind. You have to make up your own mind on=
this, though. There are many misconceptions about the flammability of Du=
racool (HC-12a). Propane is a relatively safe product. Like gasoline,=
propane is flammable, but has a much narrower range of flammability than g=
asoline and much higher ignition temperature 920- 1020 degrees vs. 80- 300 =
degrees for gasoline. Propane will only burn with a fuel-to-air ratio of b=
etween 2.2% and 9.6% and will rapidly dissipate beyond its flammability ran=
ge in the open atmosphere-making ignition unlikely. Propane, unlike gasoli=
ne, is heavier than air and in the event of a leak it will flow downward ra=
ther than up toward a ingntion source. The ignition temperature is th=
e temperature at which a fuel will ignite without the need for a spark or f=
lame. Propane has the lowest flammability range of any of the commonly=
available fuels. The flammability range is the percentage of propane in a=
ir from the lowest to the highest that will burn. Also, the typical 12=
to 15 ounces of HC12a or Duracool that is used in the air conditioning sys=
tem, is a relatively small amount of propane and even in the event of a maj=
or line break, that would not be much fuel. Much less risk than an break i=
n a transmission line near the manifold. Both Freon 12 and R134a would hav=
e more flammability danger than Duracool due to its higher pressure and lea=
kage of the oil with the propellant. ____________________________________=
______________________ You should be a whole lot more worried about th=
e 50 gallons of gasoline you carry under your GMC and the transmission flui=
d in your system than the 12 ounces of Duracool in your sealed air conditio=
ning system. Emery Stora 77 Kingsley Frederick, CO > On Dec =
10, 2016, at 7:13 PM, Espen Heitmann wrote: > > I gu=
ess I can get Duracool but I have 134a at hand, and I think I did read that=
Duracool has some drawbacks to and are flammable ? > -- > 1973 26'-3 =
# 1460 Parrot green Seqouia Known as the Big Mean Green Machine, > And ju=
st sold my 1973 26'-2 # 581 White Canyon lands under the name Dobbelt tr=
=C3=B8bbel > in Norway > > > ____________________________________=
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