NTRODUCTION
Fire is the third leading cause of accidental deaths in the United States, yet most people ignore it. More than 150 workplace fires occur every day.

HOW FIRES START
Fire is a chemical reaction involving rapid oxidation or burning of a fuel. It needs 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 - The air we breathe is about 21 percent oxygen. Fire only needs an atmosphere with at least 16 percent oxygen.

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

CHEMICAL REACTION - A chain reaction can occur when the three elements of fire are present in the proper conditions and proportions. Fire occurs when this rapid oxidation, or burning takes place.

Take any one of these factors away, and the fire cannot occur or will be extinguished if it was already burning.


HOW FIRES ARE CLASSIFIED

CLASS A - Ordinary combustibles or fibrous material, such as wood, paper, cloth, rubber and some plastics.
CLASS B - Flammable or combustible liquids such as gasoline, kerosene, paint, paint thinners and propane.
CLASS C - Energized electrical equipment, such as appliances, switches, panel boxes and power tools.
CLASS D - Certain combustible metals, such as magnesium, titanium, potassium and sodium. These metals burn at high temperatures and give off sufficient oxygen to support combustion. They may react violently with water or other chemicals, and must be handled with care.