Yeah, you can't install new Halon 1211 systems, but it's still out there. New systems are usually FM-200 or Inergen, which I believe can use the same plumbing a

Yeah, you can't install new Halon 1211 systems, but it's still out there. New systems are usually FM-200 or Inergen, which I believe can use the same plumbing as Halon. Older systems, before Halon was invented, are typically CO2 or Argon. They require a lot more agent to accomplish the job, but they're very simple. I worked briefly in a CO2 datacenter. It dated from the mainframe era, and had some gorgeous mementos on the walls. There were SCBA packs in the hallway outside, and everyone got a brief safety lecture before being allowed into the facility. The point I remember was basically "The alarm will sound intermittently for twenty seconds, then go solid for five, before discharge. If it goes off, do not stop to save your files, just run for the door. If you're not outside yet when the solid tone sounds, hold your breath and run on what's in your lungs." Apparently the CO2 is considerably nastier than Halon to get a lung-full of...