All fires are the result of three things - heat, oxygen, and a fuel source. Take away one of these and the fire stops. However, how you do this depends on the kind of fuel source which is feeding the fire. This is why there are different fire extinguishers for different situations.
Fires are grouped into 5 different classes, these are:
- Class A - combustible materials: these involve materials like wood, paper, and fabric
- Class B - flammable liquids: these include petrol, oils or paints
- Class C - flammable gases: like butane or methane
- Class D - combustible metals: such as magnesium or aluminium
- Class F - cooking oils: fires that involve cooking oils like deep-fat fryers
- Electrical fires: there is no Class E. These fires ignite from an electrical source but once the electrical item is taken away from the situation, the fire changes class
Which fire extinguisher you use will depend on the class of fire; they are colour coded to help you pick the right one in an emergency.
Wet Chemical Extinguisher
Wet Chemical Extinguishers are coloured yellow and are the only extinguishers that should be used for Class F fires.
It is worth noting that these extinguishers can be used in Class A fires but other extinguishers are more effective and this one may not put the fire out as quickly.
Water extinguishers are a solid red colour. They should be used on Class A fires.
These extinguishers should never be used on electrical fires or cooking oil fires.
Foam Spray Extinguisher
Foam Spray Extinguishers (also known as AFFF extinguishers) are cream coloured. They should be used on Class A or Class B fires.
These extinguishers should never be used on Class F fires.
Carbon Dioxide Extinguisher
These extinguishers are coloured black. They are used to treat Class B or Electrical Fires.
Due to the large pressure of this extinguisher, they should not be used on Class F fires as they can move the oil around and spread the fire.
Dry Powder Extinguisher
These extinguishers are coloured blue. They should be used on Class A, B and C fires. They can sometimes be used on Electrical Fires and Class D if they are made of a specific powder. Always read the label for more information.
Although not an actual “fire extinguisher”, fire blankets can be used to extinguish fires. They can be used on Class B or F fires.
The blanket works by cutting out the oxygen which fuels fire, so they need to form a complete seal over the top of the fire.