In short
- Fire protection works in layers: prevent, detect early, suppress.
- Aspirating smoke detection (EN 54-20, Class A) is used in almost every data hall, with four alarm stages.
- Suppression options: gas (inert or FK-5-1-12), water mist, pre-action sprinklers and oxygen reduction.
- Gas protects live IT without water but needs a sealed room that holds the concentration for about 10 minutes.
- The insurer and the authority having jurisdiction usually have the final word.
Three layers of protection
- Prevent: fire-rated rooms, low fire load, cable management, battery separation, and in some sites oxygen reduction so a fire cannot start.
- Detect early: find an overheating component before it burns, while there is still time for a person to act.
- Suppress: extinguish what detection could not stop, with as little collateral damage as possible.
Most of the value is in the second layer. A server that smoulders for twenty minutes and is unplugged by an operator costs one server; a discharge costs a room.
Aspirating detection and four alarm stages
Cooling airflow dilutes smoke, so ceiling point detectors see a fire late. Aspirating systems pull air through a pipe network to a sensitive detector. EN 54-20 sets three sensitivity classes; Class A (very high) is the usual choice in high-airflow halls.
| Stage | Meaning | Action |
|---|---|---|
| 1 · Alert | Very early smoke | Operations investigate; nothing automatic |
| 2 · Action | Smoke confirmed | Notify, check the room, prepare shutdowns |
| 3 · Fire 1 | Fire, usually confirmed by a second zone | Evacuation alarm, HVAC and dampers close, countdown |
| 4 · Fire 2 | Release | Agent discharged; doors stay shut |
The "double knock" at stage 3 prevents one faulty detector from emptying the cylinders. The detection section shows the sequence.
Four ways to suppress a fire
| Option | How it works | Strength | Watch for |
|---|---|---|---|
| Inert gas (IG-541, IG-55, IG-100, IG-01) | Lowers oxygen to about 12–13 % | GWP 0, no residue, no PFAS question | Many cylinders, pressure relief vents |
| Chemical agent (FK-5-1-12) | Absorbs heat and interrupts combustion | Compact, 10 s discharge | PFAS scrutiny in the EU |
| Water mist | Fine droplets cool and displace oxygen locally | Little water, works in leaky rooms | Insurer acceptance, nozzle approvals |
| Pre-action sprinklers | Dry pipes fill only after detection | Building protection, robust | Water reaches the equipment that is burning |
| Oxygen reduction | Keeps oxygen permanently below ignition level | Prevents fire rather than fighting it | Energy use, staff access rules (EN 16750) |
Many operators combine them: gas in the data halls and electrical rooms, pre-action sprinklers as building protection, and dedicated measures for battery rooms. HFC-227ea is now rare in new EU systems (see below).
Which option for which room
| Room | Typical choice | Why |
|---|---|---|
| Data hall | Inert gas or FK-5-1-12, often with pre-action sprinklers | Live IT, sealable room |
| UPS / battery room | Separation, off-gas detection, tested water | Gas does not stop thermal runaway |
| Switchgear room | Inert gas or FK-5-1-12 | Live electrical equipment |
| Generator / fuel | Sprinklers, water mist or foam | Liquid fuel, heat |
| NOC / office | Sprinklers | Occupied, ordinary risk |
The technology selector ranks the options for your room and constraints. Battery rooms have their own guide.
The EU gas question
- HFC-227ea: under Regulation (EU) 2024/573, new HFC fire equipment may only be placed on the market from 1 January 2025 where safety requires it. Existing systems can be serviced with reclaimed or recycled gas.
- FK-5-1-12: 3M ended Novec 1230 production at the end of 2025. Other makers still sell the molecule; it falls within the scope of the EU universal PFAS restriction proposal.
- Inert gases: GWP 0 and no restriction, at the cost of space and pressure relief.
For a new EU project that wants no regulatory risk, inert gas is the safe default. FK-5-1-12 remains attractive where space is tight.
Who decides
ISO 14520 / EN 15004 and NFPA 2001 cover gas systems; NFPA 75 / 76 cover IT and telecom spaces; EN 54-20 covers aspirating detection; EN 16750 oxygen reduction; NFPA 855 (2026) energy storage. In Germany VdS, and for FM-insured operators FM Global, often decide the system. The standards section lists all eight.
Questions about fire suppression
What is the best fire suppression for a server room?
For a sealable room with live IT, a gas system with aspirating detection. Inert gas if regulatory certainty and GWP matter most; FK-5-1-12 if space is tight.
Are sprinklers allowed in data centers?
Yes. Pre-action sprinklers, which fill with water only after detection, are common as building protection and are often required by insurers.
Is a gas discharge dangerous for people?
At design concentrations below the NOAEL short exposure is accepted, but rooms are evacuated before release. Inert gas at 40 % leaves about 12.5 % oxygen.
What is a room integrity test?
A door fan test that measures leakage and predicts how long the agent stays above the protected height. A 10-minute hold is the common target.
Sources
- ISO 14520, EN 15004, NFPA 2001, NFPA 75 / 76, NFPA 855 (2026), EN 54-20, EN 16750.
- Regulation (EU) 2024/573 on fluorinated gases. Status as of October 2026.
- Room choices are typical practice and a first screening, not a fire engineering decision.