Gooserider said:
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.
