Water is one of the most efficient fire extinguisher types. They should only be used on Class A fires including Paper, wood, fabrics, furniture, etc.
A water fire extinguisher is solid red in colour with a hose and nozzle attached, so you can direct a stream of water at the bottom of the fire. As water conducts electricity, water fire extinguishers shouldn't be used near exposed to live electricity cables. Water extinguishers are best kept alongside a CO2 extinguisher so the risk of electrical fires is covered in your building. Water extinguishers work by extinguishing the flames and soaking (cooling) the materials in the fire.
As with water, AFFF foam works on Class A fires but can also extinguish class B / flammable liquid fires. When sprayed onto a fire, AFFF foam extinguishes and smothers the flames, then seals in any dangerous vapours under the surface of foam. Foam also penetrates porous materials and cools the fire as the water in the foam evaporates. As the foam extinguisher is non-conductive and tested to the BS EN3 35,000V dielectric test, they may be used near but not on live electrical equipment. Foam fire extinguishers can be distinguished by their cream colour coded panel.
Carbon dioxide or Co2 fire extinguishers are safe to use on electrical fires. The Co2 gas is non-conductive and does not leave a residue behind that will effect the future performance of electrical equipment unlike foam or powder extinguishers. These fire extinguisher types are also effective on Class B fires (flammable liquids). Carbon dioxide fire extinguishers are distinguished by a black panel on the extinguisher body and by their horn which is to be pointed at the fire but not held in case of a freeze burn. Some newer co2 fire extinguisher types have frost free horns as an added safety feature. The most frequent extinguisher mix for efficient fire fighting is a water or foam alongside a CO2 extinguisher.
Dry powder fire extinguishers are the most flexible fire extinguisher types and are able to extinguish Flammable solids, liquids, gasses and electrical fires. These are often recommended for use on vehicles and in the home, but although they are multi purpose, powder fire extinguishers are not recommended for use in enclosed spaces, or on sensitive electrical equipment if other more suitable types of extinguisher are available. Powder fire extinguishers can be distinguished by their blue panel, and work by smothering the fire and preventing re-ignition
Wet chemical fire extinguishers have been designed specifically for extinguishing deep fat cooking fires. (Class F fires). Before the creation of wet chemical extinguishers, most industrial kitchens had foam or powder extinguishers, however normal fire extinguisher types such as these can aggravate a cooking fat fire as they cannot lower the temperature of oil risking re-ignition, and can make hot oil splash up on contact with the extinguishing agent.
When operated, a wet chemical extinguisher cools the flames and fat, and smothers the hot fat to prevent re-ignition. A wet chemical fire extinguisher has a yellow panel on its body and a long lance used to safely distribute the extinguishing agent at a distance. This specialist fire extinguisher is not intended for use on electrical equipment, but has passed the BSi 35kv conductivity test in case inadvertently used