How an FM-200 system puts out a fire

Automatic

1. The server room — FM-200 puts fires out without water or residue. Used where water would do more harm than the fire: servers, control rooms, archives.
2. Two detection zones — Gas needs both zones to agree. Zone 1 and zone 2 heads alternate, each on its own cable. One faulty head can't empty the cylinders.
3. Outside the door — Cylinders and panel stay out of the room. Nobody has to enter a burning room to check, reset or release. Tap any part to learn more.
4. A loose joint overheats — Smoke rises to the ceiling detectors. Most electrical fires start at a bad connection inside a rack.
5. Zone 1 sees smoke — Its LED turns red; the panel is told. The detector never decides. The panel does, and it now waits for zone 2.
6. Bell: first alarm — Staff alerted. No gas yet. At night nobody answers, so the system carries on alone.
7. Zone 2 confirms — Two zones agree: the fire is real. The panel moves to the second stage and starts the release sequence.
8. Sounder and flasher — Inside: get out. Outside: keep out. A different tone from the bell, so everyone knows gas is coming.
9. The room is sealed — Air conditioning stops, dampers and door close. Every opening must be shut before the gas arrives, or the agent leaks out before the fire is out.
10. Countdown — Time to leave (sped up here). Usually 30 seconds, set on the panel. The hold-off button inside the door can pause it.
11. Panel fires the actuator — The main cylinder's valve opens. The reserve stays full. The release line is monitored, so a cut cable shows as a fault before it is needed.
12. Agent flows to the room — Gauges drop; the pressure switch confirms flow. Nitrogen at 25 bar pushes the liquid FM-200 through the pipe into the room.
13. Discharge: fire out — Done in 10 seconds or less. At 7–8.5 % the agent absorbs heat and stops the flame. "Gas released" lights outside the door.
14. Wait, ventilate, refill — Keep the door shut about 10 minutes. Then ventilate, find the cause and reset. Key the panel to RESERVE while the main cylinder is refilled.

Small fire

1. A small fire starts — A cable smoulders in one rack. Still small: a few flames and a thin line of smoke.
2. Zone 1: the bell rings — First stage. Time to check. The panel outside shows which zone. Go to the panel, not into the room.
3. Key to MANUAL ONLY — Automatic release is blocked while you are inside. Always switch before going in on an alarm, or for maintenance. Detection and alarms keep working.
4. Take the extinguisher — A 2 kg CO₂ unit stands by the door. Only if trained, the fire is small and your way out stays behind you.
5. Put it out — Pull, aim at the base, squeeze, sweep. CO₂ is safe on live electrics and leaves no residue. Cut the rack's power if you can.
6. Smoke reaches zone 2 — Sounder on, but no countdown. MANUAL ONLY blocks automatic release. That is why you turned the key first.
7. Silence and reset — At the panel, outside the room. Fire out, alarms silenced, zones cleared. Log the event.
8. Key back to MANUAL & AUTO — The step people forget. A room left in MANUAL ONLY is not protected tonight. Recharge the extinguisher too.

False alarm

1. Dust, not fire — Building work near one detector. Fine dust or steam can look like smoke to an optical detector.
2. One zone: bell only — Nothing is released. Without a second zone the panel stays at the first stage.
3. Check the room — No flame, no heat, no burning smell. Key to MANUAL ONLY first, then look at every rack and the floor void.
4. Silence and reset — Then turn the key back to MANUAL & AUTO. Clean or replace that detector. Cover detectors during building work, and uncover them when it ends.
5. Why two zones — One bad head can't empty the cylinders. A false discharge costs a refill and downtime. Log every false alarm.

Hold-off

1. Working inside, system in AUTO — A normally occupied room stays in AUTO. FM-200 at design concentration is safe for people, so routine work stays in AUTO. Entering on an alarm or for maintenance needs MANUAL ONLY.
2. A small fire starts — A cable smoulders in the next rack. The smoke reaches heads of both zones within seconds.
3. Zone 1: the bell rings — First stage. He heads for the exit. On any alarm, people inside make for the door. The hold-off button is right there, by the exit.
4. Zone 2: countdown starts — Gas in 30 seconds. He is still inside. The fire is still small. Rather than lose the gas, he holds at the door and calls for MANUAL ONLY.
5. Press and hold — Held: paused. Let go: it carries on. NFPA 2001: hold-off works only under constant pressure and cannot leave the system stopped on its own.
6. Key to MANUAL ONLY — At the panel, while he keeps holding. Automatic release is now blocked, so he can let go. The manual release button still works.
7. Then put it out — Pull, aim, squeeze, sweep. Only now, in MANUAL ONLY, is it safe to fight the fire with a portable extinguisher.
8. Silence and reset — At the panel, once the smoke clears. The detectors must be clear, or the panel will not reset. No gas released.
9. Back to AUTO — Key back to AUTO once the room is clear. Hold-off is the safety net. MANUAL ONLY is what makes it safe to stay or go in.

Manual release

1. Working on a rack — System in AUTO, all clear. Routine work in a normally occupied room, so the key stays on AUTO.
2. Fire right next to him — No detector has seen it yet. People often see a fire first. Don't wait for the detectors.
3. Get out first — Too big for an extinguisher. Leave and close the door. The panel outside has the release button.
4. Press manual release — On the panel: pull down the flap, press both buttons. It skips the detectors: sounder, HVAC off and countdown start at once.
5. Countdown still runs — A last chance for anyone missed. Count heads at the door before the gas arrives.
6. Panel fires the actuator — The main cylinder's valve opens. The reserve stays full. The release line is monitored, so a cut cable shows as a fault before it is needed.
7. Discharge: fire out — Done in 10 seconds or less. At 7–8.5 % the agent absorbs heat and stops the flame. "Gas released" lights outside the door.
8. Report and restore — Tell the fire brigade gas was released. Wait, ventilate, refill and reset before anyone works inside again.

Power cut

1. Mains power fails — The panel runs on its battery. The fault lamp shows mains is lost. Everything else keeps working.
2. A fire starts — Detection works on battery too. A fault that trips the supply can also start a fire.
3. Both zones confirm — Bell, sounder, countdown, on battery. The sequence runs exactly as on mains.
4. Countdown — The room is empty. At zero the panel signals the actuator.
5. Release line fault — Countdown ends, valve stays shut. A damaged cable or failed actuator. The panel shows a release fault.
6. Lever at the cylinder — Pin out, then push the lever. Cylinders are outside, so it's done from the corridor. Room must be empty: no delay.
7. Discharge: fire out — Done in 10 seconds or less. At 7–8.5 % the agent absorbs heat and stops the flame. "Gas released" lights outside the door.
8. Repair and test — Fix the line, refit the pin. Restore mains, replace an old battery and test the release line at every service.