[johnsma22]

This is something that I deal with in my trade all the time and it's not big deal as long as you are informed. Phosgene is created when chlorine is combusted. In the HVAC trade we are faced with this any time that we have to braze on an existing system that has contained a halogenated refrigerant (any refrigerant containing chlorine, ie. R-22, R-12, etc.). I just have to take care to properly evacuate the system and purge it with nitrogen before doing any brazing. There will still be some phosgene created though.

One of the tools we used to use to find leaks in systems containing halogenated refrigerants was a halide torch. A tube on the end of a special torch would suck in a sample of air around a suspected leak. If the flame went from orange to bright green that indicated that phosgene gas was being created which indicated a leak. We just knew enough to not breath it in. Of course we all had to see what is was like to inhale a little phosgene gas and I can tell you that it's not pleasant!