There are six classes of fire that fire extinguishers have been designed to fight, by using the descriptions below you will be able to determine which type of fire extinguisher you will need for your situation.
Class A Fires = Wood, Paper and Plastics
Class B Fires = Flammable Liquids (Petrol, Diesel, Oil etc)
Class C Fires = Flammable Gasses
Class D Fires = Combustable Metals (Magnesium Fires etc)
Class E Fires = Electrical Fires
Class F Fires = Fires involving Cooking Oils and Fats