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Learning to identify and use fire extinguishers

How does someone know what to choose, when purchasing a fire extinguisher? The first step, is to look at the label on a fire extinguisher to determine its class.

The National Fire Protection Association (NFPA) has created three classes of fires – A, B and C. The letters are shown on the label of the fire extinguisher, to indicate that it’s been tested and found to be effective on those classes of fire.

Class A are fires that involve common combustibles, such as wood, paper, cloth, rubber, trash and plastics. Class B fires are those that involve solvents, oil, gasoline, paints, lacquers and other oil-based products. Class C fires are ones that involve energized electrical equipment.

The next step is to look at ratings. The numbers 1-10 before the letter A, represents the rating for that letter capability, with the higher the number, the larger A-class fire the unit can handle.

The numbers 10, 20, 40, 60, 80 before the letter B, represents the rating for the B capability; again, the higher the number the larger B class fires the unit can handle. The letter C does not get a rating, as the letter only signifies that the unit is electrically non-conductive.

There are five different types of fire extinguishers:

• Water – Absorbs the heat and cools the burning material.

• Dry Chemical – Smothers the fuel (preventing vapors from igniting) and interrupts the chemical chain reaction.

• CO2 – Removes the oxygen from the fire.

• Halotron – Interrupts the chemical chain reaction.

• Wet Chemical – Smothers and seals the fuel (preventing vapors from igniting), and removes the heat by cooling.

Rechargeable fire extinguishers, according to NFPA standards, must be recharged every 10 years. A rechargeable fire extinguisher has a metal head and a gauge that reads Charge/ Recharge.

Check a fire extinguisher’s gauge monthly, to verify the unit is still charged. If the extinguisher’s gauge needle is in the recharge area, have the unit recharged immediately.

For more information about that specific fire extinguisher, refer to a user’s manual.

According to NFPA standards, disposable fire extinguishers must be replaced every 12 years. A disposable fire extinguisher has a plastic head and a gauge that reads Full/Empty.

When putting out a fire, stand six to eight feet away from the fire, and follow the four-step PASS procedure, recommended by the NFPA: P – Pull the pin and hold the extinguisher with the nozzle pointing away. A – Aim low at the base of the fire. S – Squeeze the lever slowly and evenly to discharge the extinguishing agent. When the agent first hits, the fire may briefly flare up, which is to be expected. S – Sweep the nozzle from side to side, moving carefully toward the fire and keep the extinguisher aimed at the fire.

Fire extinguishers should be stored in temperatures ranging from -40°F to 120°F, to prevent the extinguisher from being damaged. Fire extinguishers stored below -40°F, may result in the extinguisher’s valve or hose cracking.