Charge of an extinguisher
Charge of an extinguisher is the mass or volume of the extinguishing medium contained in the extinguisher. The quantity of the charge of water or foam extinguishers is normally expressed in volume (litres) and that of other types of extinguishers in mass (kilograms).
Source: IMO Resolution A.951(23), Improved Guidelines for Marine Portable Fire Extinguishers, 25 February 2004, International Maritime Organization. Regulatory Guidance