Classes of Fire

Depending on the country you are in, there are slightly different categorizations of fire, .e.g. its slightly different for USA from UK & Europe. Here will examine the USA's OSHA classifications.

In OSHA, fires can be divided into five classes:

• Class A: These are fires involving flammable solids, e.g. wood, cloth, rubber, paper, and some types of plastics. An example of this type of fire would be a campsite fire.
• Class B: These are fires involving flammable liquids or liquefiable solids, e.g. petrol, oil, paint and also some waxes & plastics, but not cooking fats or oils.

• Class C: Class C fire involves energized electrical equipment. Such as motors, transformers and appliances. Remove the power and the class C fire becomes one of the other classes of fire. 

• Class D: These are fires involving combustible metals, e.g. sodium, magnesium, and potassium.
• 
  
• Class K: These are fires involving cooking fats and oils such as animals fats and vegetable fats. The high temperature of these types of fats and oil when on fire far exceeds that of other flammable liquids which means that normal fire extinguishers should not be used.

Note:

The only difference in U.K (HSE) classification of fire is that "Class C" is meant for Flammable Gases only and Fires of Electrical origin are mentioned under separate "Class E" which in case of USA (OSHA) is "Class C" (as seen above).