OK, while I agree it is probably alright to vent HC to the atmosphere, the EPA, for what it's worth, prohibits it.

Please see,http://www.epa.gov/ozone/snap/refrigerants/hc-12a.html

Question #7 reads as follows:
May hydrocarbon refrigerants be vented?
No. Since November 15, 1995, the Clean Air Act has prohibited the venting of any refrigerant during the service, maintenance, repair, or disposal of air conditioning and refrigeration systems. When working on a system containing a hydrocarbon refrigerant such as HC-12a® or DURACOOL 12a®, the technician must recover the refrigerant into a suitable container and safely dispose of it.

That is the word of the EPA. However, note that EPA places restrictions on the technicians, and some restrictions are not applicable to the DIYer on the side of the road.

Additionally, some states ban the use of HC refrigerants.

For what it's worth, I would and will continue to use Duracool and Enviro-safe in the vehicles I drive and maintain. If my suspicions are correct, Dupont and the HVAC industry is in bed with the government to make sure the industry stays profitable. I do not have proof. It's just my gut talking, and no, I don't have a beer gut. :)

Jurgen

While I'm on the subject we have been told that CFC12 destroys the ozone layer. Every mechanic that is worth his salt knows that if he has to find a small leak he has to go underneath to find it because freon [R12] is heavier than air. If CFC12 is heavier than than air and it holds together for 130 years as a molecule how did it bounce up to 15000 feet to destroy the ozone layer. The last time I checked gravity still works.

I am not afraid of it either, I am just pointing out that it is a little silly to stress about a few ounces of propane, and not about the up to 20 gallons of gasoline, some of which is under high pressure.

So this is a direct replacement for R-12, and I can add it to the my existing minimal charge of R-12 with nothing else to do?

Tom

turbo6bar I can see you have done your homework. I appreciate communicating with someone like you. The EPA considers all refrigerants to be CFCs HFCs or HCFCs and they have stated that these have to be recovered. I agree they should be. They never should have been made in the first place. If you will do a search on flourine you will better understand my position. They have never stated that hydrocarbons have to be recovered which they have admitted to us. Flourine is the most unstable element in the preodic table. It can combine with practically any other element with disastrous results. I am not a chemist but I believe I see the results in the world around us. Maybe flourine is the genie that should never have been let out of the bottle. I am somewhat ashamed to say that I am beginning to have a small beergut, but beer does give me a small amount of peace in this world in which we live in.

Tom, HC cannot be used to "top off" your R-12 system. If you are already running R-12, keep it. It's darn good stuff. Of course, the fact you ask about 'topping off' with Duracool means you have leaks in the system. You've got to decide how you will approach the necessary work. Do you want to save money or are you willing to spend a few bucks? Are you averse to DIY work or is this work going to be farmed out to a pro? Is your goal to maximize A/C performance, or are you trying to maintain the current level of performance?

You have a lot of options ranging from full rebuild to minor repairs to get you by. I don't know the answer to the questions I posed before, so here are some options:
1) keep topping off with R-12
2) evacuate the system, or test the system for leaks with a sniffer. Maybe you have a leaky fitting or hardware, and the repair is simple. With these old cars, though, it could be worse.
3) with duracool or the HC products, the product is a mix. If you have a leak, you can't simply top it off, since your blend will not be the same. The ideal solution is to evacuate and recharge each time. That sounds like a pain, though.
4) there are a handful of sealers that will apparently seal some pretty gaping leaks in the system. you can use these first and then run the HC refrigerant. That might be your cheapest option. If it fails, you'll be back to square one. A case of HC-12, sealer, and drying agents will set you back $60-80. It's pretty cheap stuff.

I really like the HC refrigerants, but like anything else, you have to spend the time and money to properly capture its potential.

Jurgen

Most cars today are fuel injected. Fuel injected cars have only an ounce or two of gasoline under the under the hood. If you are in an accident or there is a fire the electrical system shuts down immediately, so the rest of the fuel stays in the fuel tank. The fires I'm concerned about are not fuel related. The other question you mentioned was [Is it a direct replacement for R12. The EPA says that I cannnot call it a direct replacement for R12.] My answer is if you brought your car to me would I add duracool to Your minimal amount of R12. Yes.

What most people do not realize is that hydrocarbon molecules are many times larger than R12 or 134a molecules. If your charge of refrigerant leaked down over a period of months duracool may not leak out nearly as fast . I have had customers who lost there charge of 134a that recharged with duracool and had no more problems. This was 5 years ago.

Used ES-12 (like Dura or Freeze 12) in my 911, and works fine. Put a can of ES in my Honda that was low and had R-12 in the system and it works great now, with the mixed gasses. Been working fine for over a year now.

Am more worried about the 22 gallons of gas we all carry over our feet in the car as opposed to the gas in the A/C system in the event of an accident.

Joe

Enviro-safe is a hydrocarbon refrigerant, but their blends are inconsistant. Freeze-12 is 80 percent 134a.