Best of the ISP-Lists

Fire Suppression for Data Centers

Members of the ISP-Tech list discuss the pros and cons of carbon dioxide (CO2), Halon, and other waterless chemicals in fire suppression systems.

[July 24, 2000]

On the ISP-Tech list in July, EC had no idea what he was about to start when he asked:

"We are designing a data center. Does anyone have a ballpark figure for CO2 or FM200 fire suppression systems for a 1,000 sq. ft. room?"

[JM opened the floodgates with a simple response] "Do NOT use CO2. Use Halon."

[VB disagreed] "Correct me if I'm wrong, but I believe Halon is no longer legal, due to the same ozone-damaging properties as fluorocarbons like Freon."

[JH expanded on the Halon issue] "Halon was banned due to safety concerns. Qhile it protects your equipment, it tends to kill people in the area when it goes off. I understand that FM200 and Inergen are a lot more people-friendly. We removed Halon from our data center."

[MS noted] "As we use oxygen to breathe, anything that puts out a fire will cause people problems."

One respondent pointed out that safety's a secondary concern when things are burning up to begin with:

[JM suggested] "Fire is not people-friendly, so anything that puts it out is good. You aren't supposed to be in a room with Halon gas when it goes off, anyway. We have a timing system that first sounds a warning, and a flashing light, then about 30 seconds later, gas…"

Then TPS stepped in and provided a quick chemistry lesson:

"Halon does not force the oxygen (O2) from a room to put out a fire; it breaks up the chemical reaction of fire by attaching itself to every oxygen molecule and making the oxygen unusable to fire."

[KG debunked the Halon safety issue] "A properly configured system is set to create a 7% concentration of Halon. Exposure to 7% Halon for 8 hours produces no ill effects. 15 minutes in 15% Halon will cause cardiac sensitization; only a high concentration of Halon will cause asphyxiation."

[JL agreed] "The reason Halon was banned in the U.S. and several other nations has nothing to do with human safety, but everything to do with its supposed ozone-depleting contribution to the 'greenhouse effect.' Efforts to ban Halon may well have cited references to claimed human health hazards, but if so, such citations were 'red herrings' at best."

[PT put the debate in a broader perspective] "Humans design Halon and similar systems around human needs. There's a warning system. There's panic hardware on a door that opens out and shuts firmly. There are regulations about walkway widths and clearances, and battery-powered lights for fires during power failures. Plenty of people survive datacenter fires, so just pick the best chemical for the fire and respect your people."

—End