• Enough oxygen to sustain combustion,
• Enough heat to raise the material to its ignition temperature,
• Some sort of fuel or combustible material, and
• The chemical, exothermic reaction that is fire.

The important thing to remember is: take any of these four things away, and you will not have a fire or the fire will be extinguished.

All extinguishers are labeled to tell you what class or classes of fire they are able to fight. The recommended marking system to indicate the extinguisher suitability according to class of fire is a pictorial concept that combines the uses and non-uses of extinguishers on a single label. Letter-shaped symbol markings are also used to indicate extinguisher suitability according to class of fire.

Class A - Combustibles

Ordinary combustibles such as wood, paper, cloth, cardboard, styrofoam, trash, plastics, etc.

Flammable liquids and greases such as gasoline, oils, greases, paints, kerosene, solvents, rubber cement, etc.

Energized electrical equipment such as a computer, fuse box, circuit breakers, wiring, machinery, appliances, etc.

The best way to put this kind of fire out is to remove the source of electricity.

Flammable metals (such as magnesium, aluminum, sodium, titanium) that require special extinguishing materials found in class D extinguishers. Check the extinguisher faceplate for the unit's effectiveness on specific metals.

K - Kitchen Fires

Class K - Kitchen Fires

Cooking oils (vegetable or animal oils or fats) used in well insulated cooking appliances located in commercial kitchens.

A red slash through any fire classification symbol tells you that it will not extinguish that type of fire, and if used can be potentially dangerous. For instance, a Class A fire extinguisher using water would have red slashes through the B and C rating symbols. If you were to spray water on a grease fire, the water would cause the grease to splatter causing the fire to spread and injure the user. Similarly if you use a water extinguisher on an energized electrical appliance you are putting yourself in danger of serious shock because water is an excellent conductor of electricity.

Remember, before you use a fire extinguisher, always pull the fire alarm and call 911.

Should you fight the fire? ONLY FIGHT A FIRE IF...

• you are authorized and trained to do so.
• everyone has left or is leaving the building, and that the fire department has been called.
• the fire is contained to a small area and that it is not spreading.
• you have an unobstructed escape route if things go badly.
• the extinguisher is the right type for the fire.
• you know how to operate the extinguisher.

NEVER FIGHT A FIRE IF...

• you don't know what is burning therefore, you might not know what type of extinguisher to use.
• you don't have the right type or large enough fire extinguisher.
• the fire is producing large amounts of smoke. Burning of synthetic materials such as the nylon in carpeting or foam padding in furniture can produce highly toxic gases such as hydrogen cyanide, acrolein, and ammonia in addition to carbon monoxide. These gases can be fatal in very small amounts.
• your instincts tell you not to or you are uncomfortable with the situation for any reason.
• you don't have an exit or means of escape at your back. In case the extinguisher malfunctions, or something unexpected happens, you need to be able to get out quickly, and you don't want to become trapped. Always keep an exit at your back.
  

Click here to go to the OSHA eTools for more helpful information on whether you should "Fight or Flee". NOTE: This will open in a new page. When you are finished reviewing the information, just close that window, and continue on with this training.

If you do fight the fire . . . Remember: the PASSword. Keep your back to an exit and stand six to ten feet away from the fire. Follow the four-step PASS procedure. If the fire does not begin to go out immediately, leave the area at once.