Pyrene Fire Extinguishers WW11

[Chris Suslowicz]

Originally Posted by Tim Bell

Chris

I was told once (not a chemist) that if you mix with water on a fire you can also get Chlorine gas.

As you say - nasty stuff - marginally better than getting burned though!

Tim

Worse than that, heat + water vapour + carbon tet:

CCl4 + H2O -> COCl2 (phosgene) + 2 HCl (hydrogen chloride/hydrochloric acid)

The idea of it as a fire suppressant is that it's heavier than air and will exclude oxygen from the fire, thus putting it out. The problems arise if it doesn't put the fire out and the temperature is high enough to break down the firefighting agent. (You then get toxic and corrosive gases formed.)

Even Halon can be ineffective on some metal fires... and the only thing you can put out titanium with is titanium dioxide - burying it to exclude anything it will react with, because it will break the oxygen out of water, carbon dioxide or sand, and the halogens out of Halon and just carry on burning. (If you can get enough water onto some fires it will work by lowering the temperature, but a spray won't do it if it's a big one.)

Chris.
(Remembering that someone had a garage full of 50 gallon drums of sodium metal that caught fire - an interesting problem for the fire crew and nasty for the local residents (including a friend of mine).)