How Fires Start

Fire is a chemical reaction involving rapid oxidation or burning of a fuel. A chain reaction can occur when the three elements of fire are present in proper conditions and proportions. Fire needs these three elements to occur:

FUEL - Fuel can be any combustible material - solid, liquid or gas. Most solids and liquids become a vapor or gas before they will burn.

OXYGEN - Fire only needs an atmosphere with at least 16 percent oxygen; the air we breathe is about 21 percent oxygen.

HEAT - Heat is the energy necessary to increase the temperature of the fuel to a point where enough vapors are given off for ignition to occur.

Without any one of these factors the fire cannot occur or will be extinguished if it was already burning.

Types of Fires and How to Extinguish Them

Class A Fires

• Ordinary combustible such as wood, paper, cloth, rubber, and some plastics
• Extinguish using pressurized water, foam, or multi-purpose (ABC-rated) dry chemical extinguishers.

Class B Fires

• Flammable liquids such as gasoline, kerosene, paint, paint thinners and propane.
• Extinguish using foam, carbon dioxide, ordinary (BC-rated dry chemical, multi-purpose dry chemical and halon extinguishers).

Class C Fires

• Electrical equipment such as appliances, switches, panel boxes, and power tools
• Extinguish using carbon dioxide, ordinary (BC-rated) dry chemical, multipurpose dry chemical, and halon fire extinguishers. Do not use water.

Class D

• Combustible metals such as magnesium, titanium, potassium, and sodium
• Extinguish using dry powder extinguishing agents specially designated for the material involved.