Fire suppression

In order to provide reliable supercomputing and data storage systems, PDC has to make sure that there will be minimal damage if a fire breaks out.

The supercomputing and storage resources at PDC are housed in three rooms on the ground floor of a building at the KTH Royal Institute of Technology. These rooms are the main computer hall, the tape-robot room and a small computer hall. PDC has a gas-based fire suppression system to protect all three of these rooms in the event of fire breaking out.

If a fire is detected in any one of these rooms, a mixture of the inert gases argon and nitrogen (sometimes referred to as Argonite) is released into the room from a bank of high-pressure gas bottles (shown below). The idea is to reduce the oxygen level in the room from the normal 18% to around 11%. This is enough to extinguish fires while still enabling people to breathe, at least for a short time so they can leave the room. (The sensation would be comparable to breathing when very high up on a mountain.) A warning is sounded before the gas is released so people know to exit the room.

With gas-based fire suppression systems like this, the gas flows into the room at a high pressure, which could cause the pressure in the room to rise enough to destroy doors, windows and even walls if special measures were not taken. Special pressure equalisation dampers are opened automatically to maintain a safe air pressure level in the rooms. After the gas has entered the room, the pressure equalisation dampers are closed again to keep the gas in the room for as long as possible. For this to work, the rooms need to be sufficiently airtight. (You can read about earlier tests to check how airtight the rooms were .) If the gas is diluted too much, the fire could re-ignite. The fire code states that the gas should be kept at an effective level for at least ten minutes.

(Left) Rack of high-pressure gas bottles containing Argonite to suppress fire breakouts; (Centre) The sampling smoke detector sucks in air from the red pipes which have small holes at regular intervals & uses a laser detector to measure the smoke level. (Right) The nozzles where the gas enters the room are equipped with silencers to reduce the sound level when the gas is released. This is important as some modern hard disks are sensitive to (and could be damaged by) high sound levels.

There is also a manual Argonite release button (shown on the left in the centre photo above) in case someone notices that a fire has broken out before the smoke detectors start detecting smoke.