Class of Fire
Class A: Solid combustibles such as wood, paper, fabric, plastic, etc. Cooling (i.e., removing the temperature component) is required to put it out. Water is the ideal extinguishing agent. A, ABC or AB extinguishers are used for this fire class.
Class B: Combustible liquids (paint, grease, solvent, gasoline, etc.). These fires are put out by removing oxygen or inhibiting the chain reaction that occurs during combustion. BC, ABC and AFFF (foam) fire extinguishers are used.
Class C: Energized electrical equipment. The extinguishing agent should not be an electric conductor. Water-base solutions (water or foam-based extinguishers) are therefore not suited for this fire class. BC or ABC fire extinguishers are used. Once power supply has been interrupted, A or chemical foam (AFFF) fire extinguishers may be used.
Class D:Class D fires consist of combustible metals such as magnesium, potassium, titanium, sodium, zirconium, etc.). Special chemical powder extinguishers are used, since metals may generate oxygen during combustion. No other extinguishing agent is suitable for this fire class.
Class K: Vegetable cooking oils or animal fats. They require the use of special fire extinguishers containing a water-base potassium acetate solution which, when coming in contact with the fire, creates a soapy foam that holds the oxygen and extinguishes the fire.