This video is sort of adorable, and I think it may be as close as I'm going to get to my VP's request of a video showing a Halon fire extinguisher in action. Finishing the job with an obviously capped bottle of water is a great touch. It was probably made for the same reason that I'm searching for on: it would be nice to know in advance how long the unit will function, what the chemical looks like coming out, and the efficacy we can expect in using it. Halon is restricted under the Montreal Protocol, to which Canada is signatory, so you can't just go out behind the hangar and discharge expired bottles for training purposes. Expired units are returned to the manufacturer and the Halon is recovered and recycled.
I'm pretty sure the colourless Halon gas is virtually invisible while being discharged. The information on the can is sufficient to calculate that the contents are not in excess of what will produce an average 2% concentration in the air of the aircraft cabin. But how long will it take to be exhausted, and how big a fire is too big for it? You don't want to use the whole bottle on half the fire, but perhaps you want to be sure you have put out one part of a fire before moving on. But it lacks information on the stream rate, discharge rate, time to be fully discharged, whatever one might call it. I am, however, finding plenty of interesting things about Halon.
There are two types of Halon: 1211 versus Halon 1301. (That isn't the interesting part yet. I might also be overselling "interesting".) I just knew that the handheld extinguishers use 1211 and the installed setups like in computer rooms and cargo areas use 1301. I hadn't even thought about what "halon" meant, but it's a hydrocarbon with halogens replacing some of the hydrogens. Halon 1211 is chlorodifluorobromomethane. The number isn't just some kind of catalogue number, but a description of the molecule. The first digit specifies the number of carbon atoms: unsubstituted methane is CH4. the second digit is the number of fluorine atoms, the third is the chlorine atoms, and the fourth is the number of bromine atoms. If there happens to to be iodine on board they'll add a fifth digit for that, and presumably a sixth digit could be added for astatine, but an unstable radioactive halogen wouldn't be a good choice for a fire extinguisher. (If you didn't find an interesting part in there, sorry. It was interesting to me. I love knowing how things got their names).
Something I didn't know, and actually believed the opposite of, is that Halon 1211 is not appropriate for burning metal fires. Fortunately my aircraft does not have magnesium components. But perhaps I should double check that.
And then, just as I thought I had milked the Internet dry of useful (or interesting) information on Halon fire extinguishers, I found this study. Really if you're nerdy enough about aircraft firefighting chemicals to have read this far, you should just go and roll around in that link. Sure, it's a PDF of a typewritten document, but what do you expect from 1986? Six percent of cabin fires during the period they sampled were from "smoking materials". i.e. people lighting fires on board aircraft for recreational purposes. (There's no breakdown of tobacco versus other). The FAA built a wind tunnel out of sheet steel, a Cessna 210 and a couple of jet engines. It's not crystal clear from the description but it appears that this test rig was designed and constructed specifically for testing fire extinguishers. And damnit, they did. There are sixty pages in this document, with graphs and tables and all the data I could ask for, including the fact that a 2.5 lb Halon fire extinguisher takes ten to fourteen seconds to fully discharge. Thank you, American taxpayers.