Water fire extinguishers are of the most simplest design. This extinguisher can be used for class A fires (or in other words, fires on solid materials such as wood, plastics, furniture, paper, cloth, etc.). The extinguisher contains fresh water with added salts to reduce freezing point and a CO2 bottle inside. The extinguisher is not pressurized when not in use. It must be stowed and operated in upright position.
For operating the extinguisher, remove the safety pin, un-clip the hose, point the hose towards seat of the fire, and squeeze the handle. While squeezing the CO2 bottle top seal is pierced and releasing CO2which can pressurize the container to expel the water out through the hose with high pressure. This pressurized water comes out through the nozzle and extinguishes fire. For stopping water discharge, handle can be released. Once used, depressurize the container and extinguisher to be recharged.