Whether the system works depends less on the number of cylinders than on whether the room can hold the agent. If cable penetrations, floor voids and ceiling voids are left open, the agent leaks away quickly and the fire can re-ignite. We confirm volume, temperature range and altitude on site at design stage, and after installation carry out a room integrity (door fan) test to show the concentration will be held long enough.
ATypes and components
FK-5-1-12 (known as Novec 1230)
Stored as a liquid and vaporised at the nozzle, it extinguishes mainly by absorbing heat. It has zero ozone depletion potential and very low global warming potential. Since 3M withdrew from production, the same agent is supplied by other manufacturers.
HFC-227ea (FM-200)
A halocarbon agent stored as a liquefied gas that extinguishes by both physical and chemical action. It has a long track record and wide approvals, but as a fluorinated greenhouse gas it falls under the EU F-gas restrictions, which new projects need to take into account.
IG-541 (52% nitrogen, 40% argon, 8% CO₂)
An inert gas blend that lowers the oxygen level in the room below the point where combustion can continue. The small CO₂ fraction increases breathing rate, helping the body take up oxygen in the reduced-oxygen atmosphere.
IG-55, IG-01 and IG-100
Respectively a 50/50 nitrogen-argon blend, pure argon and pure nitrogen. Being atmospheric gases they have no environmental impact; cylinders are stored at high pressure, typically 200 or 300 bar, with pressure-reducing orifices in the discharge pipework.
Cylinders, valves and manifold
Cylinders are opened by solenoid, pneumatic or manual actuators and connected to the pipework through a common manifold. Halocarbon systems discharge their design quantity within 10 seconds; inert gas systems within 60 to 120 seconds.
Extinguishing control panel
A panel to EN 12094-1 waits for signals from two separate detection zones (coincidence detection), then starts the pre-discharge delay, operates the warning devices and releases the agent. Manual release and hold-off (abort) buttons are wired to it.
Warning devices and pressure relief
Sounders and beacons inside the room and "Gas Discharged" signs above the doors. A pressure relief vent prevents the pressure change during discharge from damaging walls, glazing and suspended ceilings.
BHow it works
- The first detector in alarm puts the panel into a first-stage alarm and operates the warning devices.
- When a detector in the second zone confirms the fire, the discharge delay starts, HVAC is shut down and dampers close.
- Occupants leave during the delay; the abort button can hold the discharge if needed.
- At the end of the delay the cylinders open and the agent discharges through the nozzles to reach extinguishing concentration.
- The "Gas Discharged" sign lights up, and nobody re-enters until the room has been ventilated and checked.
CAdvantages
- No water, powder or foam residue
- Electrically non-conductive, safe on live equipment
- Agents suitable for occupied spaces at design concentration
- Quick return to operation after a discharge
- Full integration with fire alarm and building management
DApplications
- Data centres and server rooms
- Telecom and control rooms
- Archives, museums and libraries
- UPS and battery rooms
- Switchrooms and electrical control rooms
- Medical imaging rooms
EFrequently asked questions
Is a clean agent discharge dangerous for people in the room?
Halocarbon and inert gas agents can be used in occupied spaces when the design concentration stays within the established safety limits for human exposure. Even so, the noise, sudden pressure change, loss of visibility and the toxic products of the fire itself are real hazards. That is why the delay and warnings stay active and the room is evacuated before discharge.
What is a door fan test and why is it needed?
A fan fitted in the doorway pressurises the room, the total leakage area is measured, and from that the retention time of the agent is calculated. The standards generally expect the extinguishing concentration to be held for at least 10 minutes. If the test fails, the leaks are found and sealed; otherwise a system that is correct on paper may not work in practice.
Should we choose FK-5-1-12 or an inert gas?
Halocarbon agents need fewer cylinders, discharge faster and take up less space. Inert gases need more cylinders and a larger pressure relief vent, but carry no regulatory risk on the environmental side and the cylinders can be located some distance from the protected room. We weigh room volume, available space, agent supply and long-term maintenance cost before recommending one.