What is it? What is it used for?
The intended use of fire extinguishers is in most cases to extinguish small fires in emergency situations. In the case the fire is getting out of control and grows bigger to use a fire extinguisher is no longer efficient nor is it safe, in such occurrences the professional interference of the fire department is a must.
The devise itself consists of a pressurized cylindrical body, containing some type of a fire extinguishing agent, which is discharged through a nozzle. It is usually hand held, although there are also wheeled fire extinguishers. Hand held fire extinguishers range between 0,5 and 14 kilograms, whereas cart mounted fire extinguishers are usually over 23 kilograms.
Fire extinguishers are generally divided into two general categories: cartridge-operated and stored pressure.
Cartridge-operated fire extinguishers contain expellant gas, which is contained in a chamber, separated from where the agent is stored. This separate cartage is then punctured prior to the discharged of the extinguishing agent.
In stored Pressure fire extinguishers unlike the cartridge- operated fire extinguishers the expellant is stored in the same pressurized chamber as the fire agent. The propellants differ in accordance to the type of fire agent used I the particular fire extinguisher. Nitrogen is the most commonly used propellant in dry chemical powder extinguishers; air is used in the cases of water and foam fire extinguishers.
Most common are powder stored pressure fire extinguishers. One reason is because their extinguishing capabilities cover a bigger range of different fire types.