I was going to make a repair to my a/c system but remembered the article about phosgene gas. I looked up some things and found that R12 when heated could make phosgene.

The system has been empty since I got it(over a year). I need to braze the hose and wanted to make sure it would be safe (chemically anyway).

Do any hvac or a/c mechanics know the answer please?

 

Just make the repair in a well ventilated area and don't stick your head in the fumes. I sweat copper tubing on RV A/C units regularly and have never had a problem.

 

The old R12 leak detectors ran off of propane. They had a catalyst plate that was ina propane flame, the unit had a hose connected to it. You would run the hose along the AC lines and when the leak was found the flame would turn an evil greenish color. A very big leak would turn the flame almost purple and it would smoke like all get out. That smoke was definatley dangerous. I've always been told that it was basically Mustard Gas.

The leak detectors worked great and were way more sensitive than the electronic detectors. I still have mine and use it once in blue moon.

Like Jeff said, just make sure you are in a well ventilated area and you should be ok

Bobby

 

I've got one of those laying around somewhere, haven't used it in years though.........

 

You still need to worry about the oil inside, AFAIK it's flammable.

 

Unless you have a stash of R12, if the system is empty remove the hose completely and repair or replace. Switch the R12 fittings to R134A fittings. Flush the system with the appropriate flush. Change the receiver dyer or accumulator to a R134A compatible unit.
Add 8 oz of ester 100 oil, 2 oz for condenser, evaporator, compressor, r/d or accumulator. Evacuate system. Charge at 90% of R12 spec. less 1 oz. Not resposible if you don't know what I am doing. When in doubt take it to a professional. If you have R12 add an oz or 2 of the correct oil and evacuate and recharge to spec. Can it be any simpler. Is simpler a word?

 

Not that it matters - dead is dead - Phosegene is classified as a Chocking Agent - It interferes with the transfer of oxygen to the blood - lungs fill up with fluid and a "Dry Land Drowning" happens.

 

THAT certainly doesn't sound like a pleasant way to go.

 

Years ago I helped a friend replace a comercial refrigeration system in a grocery store. According to him make sure you dont have an open pack of ciggerettes or any tobacco product close to the sorce of freon. He claimed that the tobacco could absorb the freon and poison you when you lit up. I dont know if this is true but its sure a scary thougt. This is similer to the problem of brake cleaner and heat giving off poisoness fumes. There are soo many dangerous chemical combinations out there that soon we will have to have a degree in chemistry to buy automotive chemical products.

Be Carefull !!------ Hotwrench

 

Otherwise, it doesn't hurt you, right?



If you're going to weld/silver-solder on a A/C system, just make sure it's evacuated. If it's open, and purged, it's safe.

If you're going to flush the system using one of the approved R-134 or R-12 flush kits, make sure you have purged the system of the flush liquid before welding or silver-soldering.


If you smoke...... well......I think the precautions are printed on the pack, aren't they?



Cheers,


Rick