A portable fire extinguisher by definition is an item of equipment for the purpose of extinguishing a fire. The reality is however that a portable fire extinguisher is effective only for the type and size of a fire that it is rated for.
Portable fire extinguishers are generally provided as "first attack" units in fire fighting and should be used only in early stages of fire before the fire grows to a stage that is beyond the capacity of the extinguisher. There are broadly six types of fire extinguisher;
Most portable fire extinguisher selection charts will also show the Vaporising Liquid1. type fire extinguisher (red with a yellow band). For the sake of completeness, we list this fire extinguisher, however for practical terms the Vaporising Liquid Extinguisher is no longer available for commercial or retail purchase in Australia. There are some circumstances such as aviation or marine where the use of these extinguishers may be permitted however these applications are limited.
The selection of an extinguisher must be made with the class of fire in mind.
The first record of a fire extinguisher was patent lodged in 1723 by English scientist Ambrose Godfrey. In the following 300 years there have been literally hundreds of iterations and variations on the basic design for a fire extinguisher.
If you distil all of the variations down you will find five components common to almost every type of extinguisher manufactured throughout history;
- a storage vessel
- an extinguishing agent
- a propellant (or expellant)
- a valve
- and a directional nozzle
Modern fire extinguishers continue to retain these common components, however improvements in technology have resulted in improvements to the performance (capacity and rating) of an extinguisher.