My experience with Halon extinguishing systems is somewhat different (IBM Field Information Systems, Boulder CO). If the extinguishing system went off in the computer room and you were able to remain conscious for more than 2 minutes without an oxygen mask then it wasn't working. Granted I never did figure out if the Halon merely bound with the oxygen tightly (thus removing it from the atmosphere) or if heat was required. I did know that staying in the same room was not considered survivable :-( --Chuck P.S. No, there is no good substitute yet. Nor is there any conclusive evidence that Halon has any effect on the ozone layer or its "hole".

Tim, great story! I used to work in a couple of places that used Halon too and the stuff made me nervous as hell. Surprisingly, this is the first time that I've actually heard of one of the systems being triggered. Based on what I've been told, Halon is a type of freon and is definitely considered non-enviromentaly friendly and that it's manufacture has been banned in the US along with many of the traditional freons. If so, what are they replacing it with for fire supression? I've heard that Halon is still in great demand and that stuff is worth a fortune. Keep us informed about any effects that the workers have from the Halon, I've never talked to anyone that has had direct exposure to the stuff. If some folks can't leave the area immediately you should suggest (insist!) that they provide air packs. I used to work around a LARGE liguid ammonia refrigeration plant and we had air packs pre-positioned all over the plant in case of a leak. Thank God we never had to use them. Liguid ammonia makes Halon look like a child's toy by comparision. Joe At 08:42 PM 9/13/00 -0400, Tim wrote: >A couple years ago we had a thread about Halon fire-suppressing systems >used in computer rooms. Through the school of hard knocks, >I just learned first hand how such systems operate. > >Today at work (let's just call it a "large employer in the Washington >DC area") we had a memorable incident in Operations Control when >someone (with undoubtedly good intentions) unscrewed the >solenoid controlling the valve and dumped - without warning - >2500 pounds of Halon 1301 into the room in just a few >seconds. (Operations is a *big* room. It was fitted with eight >giant red tanks of Halon.) > >Normally there'd be a thirty-second delay as an audible alarm >allowed the occupants to clear the room, but this feature is >bypassed if you go straight to the solenoid! > >The sudden pressure from the halon dump sent numerous ceiling >tiles flying, as well as large stacks of paper that were blown off the >until the firefighters showed up with air packs that allowed others >to relieve them. Some who did stick around eventually left >in ambulances (I *hope* just to run some precautionary tests.) > >The good news: the computers didn't hiccup at all during all this. > >Moderately good news: Halon dumps aren't instantly fatal. >Seeing as how I spend a good fraction of my day within a couple >of feet of some giant red Halon tanks in the concrete bunker - >oops, officially it's called "computer room" - this is good to know. >I'd been heavily trained that when the Halon dump alarm sounds, you >*get out*. Now I know a little more, especially about the dead-man >switch you can use to delay an electronically-triggered dump. > >This Halon is Good Stuff. Other than some grit blasted from the >ceiling tiles, there was zero debris left in the machinery. >What's the "environmentally friendly" equivalent used today? >Is there such an equivalent - something that will put out a fire, >but at the same time not damage vital equipment? > >Tim. >

On Wed, 13 Sep 2000 CLASSICCMP(a)trailing-edge.com wrote: This is almost certainly not a dead-man switch in any sense. Aaron Nabil