Classification of Fire Extinguishers

There are four general classifications of fires and extinguishing agents:

• Class A

  Class A fires are those that involve ordinary combustible materials such as wood, paper, cloth, rubber and plastics.

  Fire Extinguishers that contain large emounts of water are the most effective means of extinguishing a Class A fire.

• Class B

  Class B fires are those that occur in the vapor-air mixture over the surface of flammable liquids such as gasoline, oil, grease, paints and thinners.

  Fire Extinguishers that limit the amount of oxygen in the air or inhibit the combustion of the ifre are the most effective measure against Class B fires.

  Water must never be used on a Class B fire.

• Class C

  Class C fires are those that occur in or near energized electrical equipment.

  A non-conducting extinguishing agents must be used on a Class C fire.

  Water must never be used on Class C fires.

• Class D

  Class D fires are those that involve combustible metals such as magnesium, titanium, zirconium and sodium.

  Only a Class D powdered extinguishing agent should be used on a Class D fire.

  Water must never be used on class D fires.