Fire Extinguishers ?????

[crackerjack222]

Excuse me if this is a little off-topic. About 5 years ago I was driving on a country road when I saw a plume of black smoke start to rise about a mile ahead. As I arrived on scene, I saw an SUV that had hit an oak tree. The engine compartment was fully involved with fire and the passenger compartment was filled with smoke and there were traces of flame inside. There were two men standing next to the driver door. As I rolled to a stop they ran over to my truck and told me to: "back up, it's going to explode". I noticed a pickup pulled over ahead of me and assumed one of them was driving it an the other was the SUV driver. Then I began to wonder and asked them where the driver was. They pointed to the SUV. By this time the front seat was fully involved with flames. There is now a white cross at the scene.
I now carry a fire extinguisher in my truck.

 

[buickanddeere]

Halon doesn't displace oxygen like CO2, but it does have a property where it will produce some phosgene gas when it comes in contact with heated material. If I remember correctly, the temperature to start producing phosgene is north of 900 deg f. The phosgene containing plume has a very distinctive odor, so if you are outdoors get out of the plume, and indoors, exit the area until it clears...the fire will not come back indoors anytime soon once Halon is applied, so you don't have to stick around much until the fire department arrives.

Halon is astoundingly effective. When I was a firefighter, we were doing a controlled/training burn on a 2 story frame farmhouse. We trained most of the day by lighting small fires in the house and extinguishing them. Towards the end of the day, it was time to let it burn and drop into its foundation, and I asked everyone if they wanted to risk staying a little longer to see how effective a Halon extinguisher would be on a big fire. They said sure, so we did it.

We started the fire a 3 points on the main floor and let it get rolling. When flash over occurred, there was flame shooting out the top 1/3rd of all of the (tall) windows on the first floor. I approached a central first floor window and applied a sweeping ~8 second shot from a 20# Halon extinguisher into the bottom of the room. The fire went out within about 10 seconds...all of it.

Astounded, we watched as the fire re-established itself fitfully over the next 10 minutes or so. Since I still had 2/3rds of that extinguisher left, I could have kept dosing that fire periodically and kept it suppressed for a long time, perhaps even long enough to let the heat dissipate and totally extinguish it. I did not do so, however, because I had 30 hot sweaty firefighters behind me that were dreaming of that first beer.

That was probably 15 years ago, and I still have that extinguisher, ready to put out another fire.

Nothing comes close to Halon as an extinguishing agent, and that includes it's "replacements". CO2 is good but it has to be very carefully used indoors due to it's oxygen displacement properties, and a CO2 extinguisher ends up being big and heavy if it has usable capacity which makes it problematic to store in vehicles.

That's is why we use Halon on aircraft and in computer rooms.
We had some new recruits on the Emergency Response Team from the Janitorial Staff . The gas turbine standby generator control room had a smoking relay, the automatic CO2 system had been valved to due to safety concerns. . These ding dongs thought anything with electricity and liquid fuel was never water thus dry chem and C02 were interchangeable. They blasted off a couple of 20 pounders on this still energized and still smoking relay trying to put it out. That class III generator was out of service for over a year to clean and replace electrical and electronic components due to the monoammonium phosphate . I never heard the total cost numbers but it had to be into the seven figures.

 

[ray66v]

I have a friend who was in the fire extinguisher business. He and I have tested with all types of extinguishers.

Halon is the only way to go, if you are in an enclosed area. No, you shouldn't have a problem with asphyxiation.

You only need to lower the oxygen level in a room, by like 2% to put out a fire. I know, you have to see that, to believe it. But, I have. And, it's true.

In an enclosed room, it only takes a couple of seconds to discharge enough Halon, for the fire to go completely out. That's even when you discharge the Halon in the opposite direction of the fire. Humans don't even notice the difference, when the oxygen level drops that little. It's like a magic trick, when you see the fire go out.

A dry chemical extinguisher will in fact, severely choke you, if you inhale any of that powder. And, if you just ran to get it, and the adrenaline is pumping, you will be breathing heavy, and you will inhale a bunch of it. So, remember to take a deep breath, and hold it, before you discharge a dry chemical extinguisher. If you don't, you will probably remember, while your coughing your head off, that I warned you.

Yes, it's true, the plastic valve units are disposable. No one will recharge them.

Anything less than a 10 lb. dry chemical extinguisher, isn't going to put out much more than you can smother with a dish towel. So, if you are serious about being able to put out a fire, don't mess with the little ones.

 

[Argonne]

It's like a magic trick, when you see the fire go out.

That it is, Halon is the S__t! Incidentally, Halon does not work by reducing oxygen, it interrupts the chemical reaction which constitutes combustion. I used to be able to spout off what it does and put whole rooms full of people asleep, but those brain cells apparently died. Something to do with free radicals, chlorine atoms, ZZzzzz.

 

[Argonne]

... the automatic CO2 system had been valved to due to safety concerns.

There was a tragic incident at INEL (Idaho National Engineering Laboratory) in '98 where there was a fatality and several serious injuries caused by a total flooding CO2 suppression system. That prompted the immediate shutdown of many automated CO2 systems.

 

[4570Man]

I carry a 5 pound dry chemical fire extinguisher in the truck. My favorite and most useful fire extinguisher are my 2.5 gallon user rechargeable fire extinguishers. I use them several times a year and they will put out a pretty big fire. I'm sure if you filled them with a real extinguishing agent they would work better, but water is free.

 

[JRobyn]

IIRC, halon suppression systems are still allowed (and the ONLY thing allowed) in nuclear power plant emergency diesel generator rooms. They sure have a LOT of warning signs posted about evacuating if they are actuated. Those very large (locomotive) diesel engines would not fare too well ingesting either dry chemical or icy CO2.

 

[buickanddeere]

IIRC, halon suppression systems are still allowed (and the ONLY thing allowed) in nuclear power plant emergency diesel generator rooms. They sure have a LOT of warning signs posted about evacuating if they are actuated. Those very large (locomotive) diesel engines would not fare too well ingesting either dry chemical or icy CO2.

Rolls Royce gas turbines here for backup class III and class IV power. Some old Oranda and Solar gas turbines too.

 

[ray66v]

There are still Halon extinguishers available. Apparently they use recycled gas.

There are also lots of different drop in, slightly less effective replacements now.

The challenge is to get oxygen levels just below 15%, without making the air toxic.

"Oxygen levels above 15 percent allow combustion to continue, according to Joe Behnke, manager, technical services for engineered systems in Tyco's fire suppression and building products division. Below 10 percent oxygen, and the concentration does not support human life, he says.

The balance of other percentages of gases is vitally important, too. That's because carbon dioxide in concentrations above 10 percent is toxic to humans.

Generally, manufacturers of inert gas fire suppression systems combine argon, nitrogen and carbon dioxide all naturally occurring gases in the Earth's atmosphere to achieve fire suppression".

 

[daugen]

My understanding is that Halon is no longer allowed to be used for environmental reasons, which is too bad because it really works well as many have said here.
I thought like refrigeration a different chemical was forced into use.

Great thread, reminds me I need to get a pressurized water fire extinguisher for my wood shop. I have a good old fashioned garden hose not far away, which is why I haven't been in a rush, since I always drain the water out of that hose in the winter so it is ready to go. I once dumped a five pounder in the engine room of a twin gas engine Carver boat when the exhaust riser plugged and the rubber exhaust hose caught on fire. Water would have been better in a fog, but you use what you have. Not near detector head in engine room so master system did not trip, which is good. I did remember to shut down both engines before dumping the extinguisher so as not to ingest that white dust into the good engine. Needed to get home for sure... Came in on one engine, and spent months and months cleaning that dust out of the engine compartment.

I would always look for an alternative like an extinguishing blanket if I could before pulling the trigger. Now if the stove is on fire and it's going up into the cabinets, probably getting out of hand already. I was a nozzleman for many years. a gentle fog can put out most fires, unless they are too far ahead of you. Then stronger streams come into play, the ones that take the paintings off your wall, and finally surround and drown comes into play. I wonder if AFFF has a use by date; I'd like to get some outdated stuff from the fire company; ...seriously expensive.

remember to start at the "base" of the fire and work up...
A halon extinguisher and an AFFF water extinguisher would be the hot ticket.
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