Fixed CO2 fire-extinguishing system

SOLAS Chapter II-2 requires a fixed gaseous fire-extinguishing system for enclosed machinery spaces + cargo spaces + emergency generator room. The most common gas is CO2; alternatives include high-pressure water mist + inert gas (nitrogen / IG-541). Activation is a two-step deliberate release (release-cabinet key + pin) with automatic evacuation alarm + interlocks that shut engine-room ventilation before discharge. Fatal-to-humans in the flooded space; SMS and drills must exclude release with personnel inside.