Possible Wiki Item - What To Do With A Runaway Stove

[Mo Heat]

Every setup of the sort that I saw had safety features up the wazzoo to prevent accidental discharge, and "wake the dead" alarms to warn any people inside to evacuate NOW. The alarm was supposed to sound for at least 30 seconds to a minute before the system would dump, which was about twice as long as it would take to evacuate the space.

Yes it was possible to get killed by one of those systems, but it was not easy.

Gooserider

That's interesting... now let me tell you a WWII story, errr, I mean a halon story...

I worked in a printing factory where we had several 6 color, central impression presses (machined drums 6' in diameter and 45" wide that ate 600 lb rolls of paper and flexible packaging film). The six colors were achieved using six "pans" surrounding the drum that were fed using 5 gallon ink cans with semi-submersible pumps and a drain-back to maintain a tight viscosity. So you had about 30 - 50 gallons of solvent (toluene, ethyl alcohol, 2-nitro-propane, hexane, etc.) in inks and/or adhesives (for laminated runs) surrounded by heating ducts used to dry things quick enough to roll the film up at speeds from 500 - 700 fpm, which is humming for one of these machines.

A brand new press was installed with a halon system. I watched them put it all in and was amazed at the 24 or 32 big welding sized "bottles" (the 5 foot tall type) of halon that fed the thing. I always wondered what it would be like if that dude "went off". I didn't have to wait long...

One of the older presses that sat next to this new press was used only for thermal stripping (seal on old potato chip packages). The adhesive was toluene (toluol) based and highly flammable. One of the heaters got a little too hot and sparked a fire that instantly engulfed the press and had flames licking off the ceiling about 20 or 25 feet up with a huge plumb of dense black smoke. Normally, a couple of us would grab a CO2 extinguisher and run toward the calamity (we were young and brave/stupid ). But there was a new press operator that had only been running the newest press for a couple months and he didn't know the drill. He was the panicky type, too. Boss's son-in-law as it were.

Well, as soon as he sees the flames, he runs to the nearest fire alarm mounted on the I-beam next to his press. At least he thought it was a fire alarm. It was actually the trigger for the halon system on his machine, which was happily running around 550 fpm printing Frito's bags. I was mounting some printing plates on the other side of some lockers when I heard what sounded like a jet engine firing up about 30 feet away. I was stunned. I'd been there for about 5 or 6 years and thought I'd seen and heard it all by then. I was wrong.

As I wandered out to see what was happening, I was met with a 3 foot deep layer of halon gas that reminded me of a good rock concert I had been to recently. That seemed pretty cool, but the noise was deafening. I noticed the thermal stripper machine on fire and a cloud of halon still being blown onto the new press next to it, still printing Frito's bags somewhere inside the cloud of halon, and creating an ever deepening layer of halon gas on the floor. Naturally I headed for where I knew the nearest CO2 fire extinguisher to be, and managed to find it by feeling my hands around the I-beam, even though the halon gas was completely concealing everything from my belt to the floor.

Me and another guy quickly got the thermal stripper out like we always did (it went up about once a year). By now the halon had exhausted itself and was beginning to drop to about 2 feet deep as it rolled into the next building. We had fun wading around in it for about 10 minutes. We didn't realize it displaced oxygen at the time, but as I said, we were young and brave/stupid.

It was rumored to have cost $10 or 20 thousand dollars to recharge the halon. Not sure if that stuff was that expensive, but I can tell you that the pressman was reassigned to the office after that incident. He left the company when the boss (his father-in-law) "resigned" about a year later.

 

[erikdhafaB]

I haven't read the entire thread so someone may have already said this, but I'll say it anyway: I've heard that if you get a chimney fire, one way to deal with it is to get your dry-powder fire extinguisher, open the stove door, discharge the ENTIRE fire extinguisher into the stove/flue, and then slam the door shut again. Supposedly the heat of the stove/fire will cause the dry powder (sodium bicarbonate) break down and release CO2 which wil kill the fire.

That would be more effective than some approaches, but it has one problem - you are blowing a large volume of gas into the fire along with the dry chem. Granted the gas is supposed to be Nitrogen, which is flame suppressing in and of itself. However that gas going into a mostly closed box, and isn't going to go up the chimney as fast as the extinguisher is going to be blowing it out. It has to go somewhere, and that somewhere wll be back out the door at you, along with any loose embers, ashes and other possibly burning material that is light enough to blow around. You are now standing with an empty extinguisher in a room with a bunch of embers scattered around - you may have put out the chimney fire, but you may not have improved the overall situation. :bug:

That is why I argue in favor of something that can be thrown into the stove without putting any pressure into it at the same time - The fire is best kept in the metal box, even if it is over enthusiastic there.

Gooserider

So perhaps if the guy with the "modify the very first piece of smoke pipe above the woodburner to have a stub of 3/4 inch black iron pipe attached to its side, which would be connected to a cylinder of carbon dioxide" system changed the cylinders so that it injected dry chem into the flue he might have a much better product: the benefit of shooting dry chem into the flue/stove without opening the stove and letting oxygen in or allowing embers to be blown out the open doors by the force of a fire extiguisher sprayed into the contained space of the firebox.

 

[Gooserider]

I've never had the dubious pleasure of being around one of those things when it went off, but the rest of it sounds about right... Of course these days, they get so anal about such things you'd have a hard time NOT knowing about all the hazards and proper procedures...

The one that cracked me up was the safety training course where they told us that we shouldn't attempt to cleanup any drips of blood if someone cut themselves, but instead should call for the haz-mat team, Including OUR OWN! I can see that as a reasonable rule if it was someone elses leakage, but I hardly think I'm likely to catch anything I don't already have when cleaning up my own blood...

I never worked in a halon protected space, but have been in several as a visitor, and they all had tons of signage warning that if you heard alarms you needed to leave and all that.

Gooserider

 

[Mo Heat]

I never worked in a halon protected space, but have been in several as a visitor, and they all had tons of signage warning that if you heard alarms you needed to leave and all that.

Worry warts. That stuff was cool!

 

[Marty]

This is a bit of a side but:

I've found that if I have a fire that's looking to head north of a temp I'll be happy with, I can get it under control by shoveling some the ash out of my ash bucket onto some part of the inferno. This insulates part of the burn from the stove and keeps her from speeding too much around the bend. Try to avoid it though cause I don't like to clean out my ash twice.