In fire extinguishers with explosive cartridge the extinguishing gas is held under pressure by a thin breakable seal. Upon activation the explosive cartridge ejects a projectile which breaks the seal thus releasing the gas for fire fighting.

For sea transport fire extinguishers fitted with explosive cartridges are assigned with UN number UN 1044 Class 2.2 (FIRE EXTINGUISHERS with compressed or liquefied gas).

Special provisions states “Fire extinguishers under this entry may include installed actuating cartridges (cartridges, power device of Division 1.4C or 1.4S) without changing the classification of class 2.2 provided the total quantity of deflagrating (propellant) explosives does not exceed 3.2 g per extinguishing unit”