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.
Characteristics of Portable Water Extinguisher
Simple extinguisher where extinguishing medium is water with added salts to reduce freezing point.
Expellent used is carbon dioxide bottle which is used as a cartridge. It can be easily replaced with the spare while recharging. Used bottles can be recharged from shore.
Since discharge contains only fresh water, no cleaning up is required.
Water extinguisher extinguishes fire in two ways. One is by cooling property of the water, by which it takes away the heat. Second is by covering the material on fire with a blanket of steam, formed by evaporation of the water, which helps to cut the oxygen supply for firing (Smothering)
It cannot be used on live electric equipment since water is a good conductor of electricity.
Do not to keep the extinguisher in high temperature areas, since increase in temperature causes pressure of carbon dioxide gas to increase and it may result in accidental release of the gas to the container.