[Gmcnet] Duracool compatibility

[Emery Stora]

On Aug 11, 2008, at 9:12 AM, Dennis Lepard wrote:

> Emery,
>
> When I tried to buy HC12A locally I was told at Auto Zone, Advance  
> Auto,
> Napa and car quest that it was illegal to sell or use this product  
> in New
> York State because it an explosive. My argument was I have a motor  
> home that
> can carry 50 gallons of gasoline and 70 lbs of propane plus engine  
> oil and
> tranny fluid all of which are fammable or explosive. I am not  
> worried about
> 18 ounces of HC12A in the air-con.
>
> Dennis Lepard
> Depew,NY
> '76 Palm Beach


Propane is not an "explosive".

Propane is a relatively safe product.  Like gasoline, propane is  
flammable, but has a much narrower range of flammability than gasoline  
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 between 2.2% and 9.6% and will rapidly dissipate beyond its  
flammability range in the open atmosphere-making ignition unlikely.   
Propane, unlike gasoline, is heavier than air and in the event of a  
leak it will flow downward rather than up toward a ignition source.

The  ignition temperature is the temperature at which a fuel will  
ignite without the need for a spark or flame.

Propane has the lowest flammability range of any of the commonly  
available fuels.  The flammability range is the percentage of propane  
in air 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 system, is a relatively small amount of propane  
and even in the event of a major line break, that would not be much  
fuel.  Much less risk than an break in a transmission line near the  
exhaust manifold.

Now, having said that I am sure that we all have seen pictures on TV  
of a propane facility exploding with a large bleep or fire ball.  So,  
it can happen but those are leaks of extremely  large amounts of  
propane so that the propane / air ratio is less than 10% air close to  
the tank.   I have seen a propane bottle thrown on a fire years back  
(at a Watkin's Glen US Grand Prix) when some drunken fans were  
"celebrating" around campfires at night.  I thought that it would  
explode but what happened was that when the cylinder heated up it  
opened the pressure release valve and there was a jet of fire until it  
cooled down and then the safety valve went out and the fire stopped  
until it heated up again and then it repeated itself.  This continued  
until the cylinder was empty.  There was no explosion.  I now know  
that this was because there was no oxygen or air inside the cylinder  
so the propane could not burn without at least 2.2% air.  The same is  
true inside your GMC air conditioning system.

Some states have fire department regulations that prevent a licensed  
installer from using a flammable substance in an air conditioning  
system of a vehicle.  It appears that the way these laws are written  
it only affects a licensed person.  An individual doing it himself  
apparently does not fall under these laws.  I am amazed that there  
would be a fire regulation on this but nothing to prevent an  
unlicensed person at a filling station from filling your car with  
gasoline which is by far much more dangerous.  Or, from filling your  
transmission with a fluid which is also flammable.

It is not illegal to sell or use the product.  The following is a  
quote from the EPA's internet site:

"The Clean Air Act only granted EPA the authority to regulate the use  
of alternative
refrigerants, not the sale of them. Even if EPA determines that an  
alternative is
unacceptable, it is still legal to sell it. However, putting it in a  
customer's A/C or
refrigeration system is considered use, not sale, so a service  
technician who charges a
system with an unacceptable refrigerant may be subject to a $25,000  
fine and up to five
years' jail time."

So you can see that it is a licensing regulation (or law) and not a  
use law.

Emery Stora
77 Kingsley
Santa Fe, NM