I should not have required my old (non CE marked) brain to recall something over one day old! It is halon, not halogen, that we use in our old (1972?) EMC chamber. I believe that halon is far less a toxic threat than halogen, which is the "family" of agents which includes chlorine etc.
Halon is heavier than air and rapidly drops to floor level. If breathed, one speaks with a deeper voice, as opposed to the high pitched voice often demonstrated with the helium from baloons. Given the small size of our chamber, and the large, well sealed door, the procedure in the event of a pending halon dump is to leave the chamber and close the door. However, as I recall (again treading on dangerous ground) we have not had a halon dump in at least twenty years. If halon represented a serious threat to human life as a fire extinguishing agent, I doubt that factory insurance cariers would allow its use, as cost to repair a damaged semi-anechoic chamber would be far less than that to settle a death claim. George Alspaugh Lexmark International Inc. CAUTION: All of the above comes from a non-CE compliant brain! ---------------------- Forwarded by George Alspaugh/Lex/Lexmark on 11/17/99 03:54 PM --------------------------- slacey%[email protected] on 11/17/99 03:25:29 PM Please respond to slacey%[email protected] To: s_douglas%[email protected] cc: emc-pstc%[email protected] (bcc: George Alspaugh/Lex/Lexmark) Subject: RE: Shielded Enclosure Fire Hazard Scott, I beg to disagree, ... but, Halon, along with Freon and other compounds was banned by the Montreal Protocol, ostensibly to protect the ozone layer. Interestingly, the Freon replacements must, per the treaty, be phased out in 20 years - by coincidence about the time when the international patents expire. No suitable replacement for Halon has yet been found, and the U.S. military has bought up much of the existing stocks for vehicle and shipboard fire protection systems. If I remember correctly, Halon can cause suffocation by displacing oxygen, rather than causing toxicity. When I worked in a Halon protected room, our instructions were to take a couple of deep breaths before the system fired, and hold our breath during escape. Scott Lacey -----Original Message----- From: Scott Douglas [SMTP:[email protected]] Sent: Wednesday, November 17, 1999 1:53 PM To: [email protected]; [email protected] Subject: RE: Shielded Enclosure Fire Hazard George, I once worked in a laboratory that developed the Doppler weather radar we all see on TV today. In our just built (in 1979) control room, they put a halogen extinguisher system. Halogen works by displacing the oxygen and thus the fuel for the fire. No fuel, no fire. The system could fill the entire control room, 50' x 80' in less than 30 seconds. We had big klaxon alarms and a disable mechanism, but strict rules to just run like hell. We had a 10 second warning bell that went off just before the gas came down. Point is, it wasn't so much the ozone layer that made halogen fall out of favor, it was the severe threat to human life. The gas is odorless, tasteless and invisible, so if it went off you wouldn't know until too late. I recall they told us that you would not live 30 seconds in a room filled with halogen. The several false alarms caused us to evacuate and we had to call the fire department to ventilate the building for 60 minutes before we could get back to work. Halogen is certainly an extremely effective means of suppressing fire, but operating costs and impact on operations play a big part in its use (or lack thereof). The gas is expensive and, while there is little damage to facilities or equipment from its use, there can be human consequences to deal with. Scott [email protected] ECRM Incorporated Tewksbury, MA USA --------- This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to [email protected] with the single line: "unsubscribe emc-pstc" (without the quotes). For help, send mail to [email protected], [email protected], [email protected], or [email protected] (the list administrators).
