Fire Extinguishers are typically used as a preliminary measure to eliminate fire that has aroused. Small fires are classified according to the nature of the burning material. Class A fires involve wood, paper, and the like; Class B fires involve flammable liquids, such as cooking fats and paint thinners; Class C fires are those in electrical equipment; Class D fires involve highly reactive metals, such as sodium and magnesium. Water is suitable for putting out fires of only one of these classes (A), though these are the most common. Fires of classes A, B, and C can be controlled by carbon dioxide, halogenated hydrocarbons such as halons, or dry chemicals such as sodium bicarbonate or ammonium hydrogen phosphate. Class D fires ordinarily are combated with dry chemicals.
