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This bit of information showed up in the Cadillac group today. As my garage contains both TIG and MIG welders as well as lots of cans of cleaners including brake, I can see a problem.
http://forums.cadillaclasalleclub.org/index.php?topic=123702.0
I'm posting this on all my forums and I shall print it out and present it to every one with a garage and tools. It is worth a second thought. I hope this link works.
Stay safe, Tom

Ok, so the claim is that

Quote:

I'm no chemical engineer, but let's look at this grossly.

"phosgene" is Carbonyl dichloride, i.e., C-O-Cl2 (Carbon, Oxygen and 2 chlorine atoms).

Obviously carbon and oxygen are overwhelmingly common here on Earth on an almost infinite variety of combinations

Tetrachloroethylene is Cl2C (or CCl2) . It is a colorless liquid widely used for dry cleaning of fabrics, hence it is sometimes called "dry-cleaning fluid."

According to Wikipedia (FWIW)

Quote:

So, on the face of it, this sounds pretty bad. But...

Anyone who has used some spray can with Tetrachloroethylene (like brake cleaner) knows that the stuff evaporates almost instantaneously. Once evaporated, it's not there to combine under arc welding into "phosgene".

I think this is an "old wives tale" because otherwise, there'd be many deaths reported of guys using TIG/MIG (arc) welders around brake cleaner!

I'm not saying lean over and breathe deeply while you are both spraying brake cleaner and welding something, but that scenario is not real.

Craig

You've given the formula for tetrachloroethylene incorrectly (tetrachloro means FOUR chlorine atoms, so Cl2CCCl2, or (Cl2C)2) but otherwise I tend to agree. Years back in my industrial chemistry lab we had a vapor degreasor running trichloroethylene in close proximity to a carbon arc lamp. It wasn't uncommon to smell traces of phosgene when the carbon arc was running; the room had reasonable ventilation, we tended to keep our distance, and we're all still here 50+ years later. That said, it still is wise to allow time for chlorinated solvent vapors to clear the area beforehand.

The potential for phosgene formation is there with any of the chlorinated solvents, there are many including methylene chloride, trichloroethylene, tetrachloroethylene, and carbon tetrachloride when in contact with heated sources. That's one reason why carbon tetrachloride fire extinguishers which were common in my youth were banned.

I use brake clean a lot in the Pushbutton business, it is my final step in cleaning, and it does a great job economically.
I worked at a shop where we had a hot bath trichlor cleaner, once in a while the hillbillies in that department would turn the heater on without turning on the city water flow to the cooling coils at the top of the tank and the place would fill up with noxious fumes.
I have been waiting for that bill to come due for 30 years, so far, nothing. Knock on wood.

Anybody who applies high voltage to volatile chemicals is an idiot.

I suppose this knucklehead never heard of using compressed air to clear surfaces of chemicals.

If I was him I would keep my mouth shut out of shame.

This is not a new issue, This is from the AACA forum back in 2009:

http://forums.aaca.org/f169/welder-argon-brake-cleaner-265619.html