In the UK the different types of fire classes are classified using the European Standard Classification of Fires, which is recognised across the EU.
There are six different types of fire classes which are based on the energy source that has caused them.
Classifying a fire according to its energy source also makes it easier to choose the most appropriate method of fighting the fire. For example, some types of fire extinguishers are better suited for use on certain types of fires than others. Using the wrong type of fire extinguisher on certain fires could cause more harm than good, and create an even bigger catastrophe, so it is important to understand the energy source before selecting the equipment required to extinguish a fire.
The following are the classifications used in the UK:
Class A – Ordinary combustible fires
Materials involved in these types of fires include paper, wood, textiles, rubber, some plastics and other organic carbon-based compounds.
Class A fires can be extinguished using appliances and fire extinguishers that spray water. The water cools the fire, removing the heat supply which is essential for the fire to burn.
Class B – Flammable liquids
Examples of liquids that are flammable include petrol, kerosene, alcohol, solvents and paints. Fires involving these volatile chemicals burn at a very high temperature, give of lots of heat and often spread quickly. These fires also produce toxic smoke and fumes, which can make situations involving these types of risks very difficult to control.
Class C – Flammable gases
Commercial premises used to store flammable gases such as butane, propane and petroleum gases can be very dangerous. Even a single spark has the potential to create an explosion consequently there are many laws to ensure flammable gases are stored securely in sealed containers and many insurers insist on having additional gas detection systems installed to provide an early signs of gas leakage.
Fires involving flammable gases are one of the hardest fires to put out as it can be hard to isolate the source of leakage and stop the release of gas or flammable liquid.
Class D – Metal fires
It requires a lot of heat to ignite most metals, but metals are good conductors and transfer heat away quickly to their surroundings so can be the cause of a fire. Powdered metals and metal shavings are easier to ignite than solid lumps of metal and therefore a much higher fire risk.
Standard fire extinguishers will not put out a class D fire and, if used on this type of risk, will almost certainly make the situation worse.
Class E – Electrical fires
Electrical fires can be caused by faulty equipment, damaged wiring, short circuits, and overloaded switchboards and sockets. Although electrical fires are not strictly a fire class of their own, electricity is classed as a source of ignition and has its own special fire safety requirements.
You should never try to extinguish a fire caused by electricity using water or foam as this acts as a conduit and could electrocute the person holding the appliance.
Class F – Cooking oil fires
Class F fires involve cooking oil and fats. These ignite at very high temperatures making them difficult to extinguish.
Standard fire extinguishers will not put out a class F fire and, if used on this type of risk, will almost certainly make the situation worse.