Answered
What is in a fire extinguisher?
That depends entirely on what type of extinguisher it is. Air pressurized water extinguishers contain compressed air and water, the former forcing out the latter up through …an uptake tube and out the hose. For use at low temperatures, an antifreeze might be added to the water Foam extinguishers are similar to air pressurized water extinguishers, but the water is mixed with foaming agents and small holes are added near the top of the uptake tube to aerate the extinguishing agent. Dry chemical extinguishers contain a powdered agent (bicarbonate of soda, ammonium phosphate, potassium bicarbonate, potassium chloride, &c.) and a compressed gas, usually nitrogen. The latter propels the former out the nozzle or hose. Carbon dioxide extinguishers contain liquefied carbon dioxide under high pressure. Halon and other clean agent extinguishers contain a variety of chemicals of varying risk to the ozone layer. Dry powder extinguishers are typically buckets containing the extinguishing agent (sodium chloride mixed with thermoplastic, powdered copper, graphite, sodium carbonate, &c.) which are shoveled onto the burning metal. Sometimes these agents are placed in containers more typical of what we think of as a fire extinguisher. Kitchen or type-K extinguishers are similar to foam extinguishers, but contain a soap-like emulsifier that brings the burning lipids into solution with the water. Dry chemical and dry powder extinguishers are also available in cartridge-operated forms where a large amount of powder is contained in the main body of the extinguisher, and gas cartridges are attached to pressurize the unit. This allows the unit to be recharged more quickly an on site, not requiring special equipment. In this case, the pressurized gas is typically carbon dioxide, and is stored in a separate container, punctured at the start of use. (MORE)
