The resurrected fire extinguisher thread reminded me that I have two Halon extinguishers bought at a home show over 20 years ago. They’ve never been used and still show pressure in the green arc on the gauge.
I’m assuming they are still operational and safe to use. Anyone know otherwise?
They leave no residue when used, which is a plus for inside the house. Are there major health risks?
The major risk is that they work by displacing oxygen which fire needs to keep burning, but which is also a thing you need if you like being alive. Using them in an enclosed space could cause suffocation by displacing all the oxygen from the room - and the onset of unconsciousness from this type of suffocation can be rapid and symptomless (you don’t cough or feel short of breath - you just lose consciousness).
Being in an enclosed space with an uncontrolled fire is also bad of course, so it’s about balancing risks.
Manufacturers of chemicals are required to provide Material Safety Data Sheets (MSDS). Any time you’re curious about a chemical, you can google the name and “MSDS” and you’ll get all kinds of hits. I just googled and saw results for Halon 1211 and Halon 1301; you’d have to check your extinguishers to see which one you have.
Here’s an MSDS (PDF) for Halon 1211:
Section 11 gives health hazard info.
Halons are supposed to be good for fire suppression because they can chemically interrupt the combustion process and snuff out a fire at low concentrations without having to displace all of the available oxygen. So if you have a room with a built-in halon system, you can size it so that it dumps in enough halon to put out the fire, but not so much that it asphyxiates all the people in the room (by displacing all of the air). The same can’t be said for CO2 fire suppression systems, which work by displacing atmospheric air and blocking the fire’s access to oxygen. If you’re in a room when a built-in CO2 system dispense, and you don’t leave the room, you will die.
Since you’re talking about a handheld extinguisher, you’re unlikely to create an asphyxiation hazard unless you dispense its contents into a small closet with a person trapped in there behind a closed door.
It looks like you need a halon concentration of at least 5% to effectively suppress fires. The Halon 1211 MSDS says there aren’t really any toxic effects at this concentration. Minor symptoms start showing up at 7.5%, and you can get serious problems after exposure to 20% concentration for a couple of minutes, at least if you’re a rat. Bottom line, if you spray a halon extinguisher at a fire, you probably want to leave the room as soon as the fire is under control - and really this would be true with any extinguisher, since the room probably already has a hazardous amount of toxic smoke from the fire in the first place.
Any health hazards for a halon extinguisher should be compared to the hazards of other extinguisher technologies, and also to no extinguisher at all. Halon is better than nothing, but dry-chemical extinguishers are certainly less toxic than halon (although as you point out, they leave a lot of residue). You get to decide whether the hazards of halon are worth the benefit of not getting dry-chemical extinguisher powder everywhere.
Thank you both for the information. I have one of these in my garage, the other in my pantry. Perhaps I’ll move the one in my pantry into my pole barn where I keep the tractor and mower. It’s 1200 sq, ft, so less chance of asphyxiation out there. I do have a dry chemical as well. it might be safer in the kitchen area regardless of the possible mess.
Halons are powerful destroyers of the ozone layer. The Montreal Protocol phased out their use by 2000 (1994 in the US). So keep the halons in their canister until they are needed in an actual emergency. Halons Program | US EPA
Weren’t they developed for computer centers and perhaps libraries? Where suppressing the fire could do more damage than the fire itself?
Halons do not work by displacing oxygen, they work by interrupting the chemical reaction that is a fire. The chlorine, fluorine, and bromine are super reactive and break loose as the halon molecule is heated, those molecules react with the free radicals in the combustion zone and turn into byproducts that don’t want to continue the reaction. What a fascinating modern age we live in.
If you have a hand held portable fire extinguisher, it’s Halon 1211. Halon 1301 is a total flooding agent, the kind you’d see in a fixed system in a data center or records storage where you don’t want water. There isn’t much of a hazard with the portable extinguishers on the plain agent side. You’d need a giant extinguisher to hit the percentages where you’d see physiological effects.
More impactful are the byproducts from halons hitting the fire. Hydrogen fluoride (which turns into hydrofluoric acid when it contacts water) is one of the big worries, but none of the chlorides, bromides, or fluorides are particularly healthy. Products of combustion are generally never good for you, but the post-halon use ones can be really bad. One of the big benefits of halons was that they didn’t leave a mess and were nonconductive, so you can discharge it on computer equipment and it will still work post-fire (barring the fire damage, of course). There was zero cleanup needed due to the agent itself, unlike dry chemical or water. Just make sure you ventilate the space soon after the fire is out (we have to provide ventilation for fixed systems for this reason).
All of that said, Halon 1211 is still used in the fire extinguishers on airplane flight decks. A pretty tight place with nowhere to go. A halon replacement called Halotron has been used in lieu of Halon 1211 for 20+ years now. Halon 1301 is still the only agent used for the extinguishers in airplane engines, no one has come up with something better. Amazing firefighting capabilities.
The ozone depletion capabilities of the halons are really, really high, which is why their production stopped in 1994. Prior to the cutoff, production was dialed up to 11 right up to the end date. There were huge stockpiles of halon that got us through until now. The clean agents that were intended to replace the halons, like Novec 1230, FM200, and a handful of others are now being phased out due to ozone depleting potential or as part of the PFAS panic.
Buy stock in inert gases. Nitrogen and argon are the wave of the future.
My apologies for mis-stating the action of these extinguishers above. I took that in good faith from a supplier in a data centre upgrade (past)project.
Yes, almost always present in mainframe computer centers. They would put out a fire, without getting the multi-million dollar computers wet or contaminated like other fire extinguishers.
For safety considerations, the rough figures were that about 6%+ Halon was enough to put out a fire, while humans don’t start to lose consciousness until 12%-18%.
So they were commonly sized to get to a max of about 7.5% of the air volume of the computer room. That would put out the fire, but still allow humans time to evacuate the room. (But obviously not good for your lungs. Or for the ozone, though that wasn’t much of a consideration back then.)
Halon 1211s are also carried in airliner cabins. They’re the primary, and on many models the only, fire extinguishers carried.
Upon detecting a fire or smoke in the cockpit, putting on oxygen and smoke goggles is job 1, then somebody attacks the fire with the halon extinguisher while somebody else flies.
As explained to us, the concern about halon in enclosed spaces is mostly overstated, unless you’re in a space that’s designed to cut ventilation and flood it. Our immediate concern is to prevent smoke and fumes overcoming your ability to breath or your eyes to stay open. Cockpits are also heavily ventilated; all that equipment has forced air cooling. Which is distinctly a mixed blessing if there’s a fire going on in the area.
I’ve shaken my head for the last 25+ years regarding the flight deck fire extinguishers required by the FARs. They want a BC rated fire extinguisher, which is appropriate for ignitable liquids that are electrically charged. The last time I looked (which was 7 years ago, but who’s counting), there aren’t a ton of flammable liquids on the flight deck of an airliner. We’re not putting live fuel to the back side of the fuel tank gauge, nor is the oil gauge under pressure behind the dashboard. Not a lot of liquids in a glass cockpit. The smaller Halon 1211 extinguishers (and the Halotron ones) don’t get an A rating until you hit 5 pounds. But 5 pounds is far too heavy for a flight deck (you’d better maintain the oh-so-critical to flight crash axe, though).
The rest of flight deck is all class A products - cloth, plastic, etc. The fire extinguisher we’re mandating has zero use for the environment pilots are in. I’ve wondered for years if the pilots of SwissAir 111 would have had a better chance of survival if they had a real fire extinguisher.
Not that the water extinguishers (only on 30+ seat air carrier aircraft) are much better, but I suppose it’s something. The stream is comical, I’ve seen better from squirt guns. When coffee pots and cans of soda are your best line of defense, we should be reevaluating our plan.
I did not know that halon was still in use in the flight industry. The US Army used to use halon in its track-vehicle fire suppression systems, but it was my understanding that they replaced it with a different chemical. Always hated that stuff. Bradleys had some maintenance and repair tasks that required the partial dismantling of the fire suppression system to get to. Sensitive bottles, easy to set off on accident if you didn’t install the plugs before removal.
You’re the pro in this area, not me. But I’ve had my own curiosities for awhile as well.
Cockpit and cabin fires are the stuff of nightmares in our industry. It always seemed to me the tools we had were much too little much too late. The whole fire control process depended on prevention rather then successful containment. Swiss 111 notwithstanding, the fact airliners aren’t regularly falling out of the sky suggests the total process works well enough.
But I always felt like we were nearly naked in the face of a serious credible threat. At least the advent of full-face breathing masks solved the half-assed 1950s workaround of separate mask & goggles.
I used to go into a tape vault* with a Halon fire suppression system. It was bad enough you could get locked in the vault, but if the fire alarm went off the door would shut and the little room would fill with Halon. You can bet we put large had to move objects in the doorway whenever the door was open. And WTF was there no way to open the door from the inside?!?!
*9 track magnetic tape. All the data you hold on your laptop took up 10X12 ft. room filled with tapes back in the day of steam powered computers.
LOL! Did you guys wear onions on your belt to keep the “bad humors” away?
It was the style at the time.