Composition of a Dry Chemical Extinguisher

Fire extinguishers today have developed into a simple and effective tool to protect home and business. These devices are meant to fight fire in its incipient, or beginning, stage. Fires are classified into one of five specific types: Class A, ordinary combustibles; Class B, liquid fuels, oils, gas and grease; Class C, electrical; Class D, burning metals; and Class K, cooking combustibles, oils, fats and shortening. Having an extinguisher at hand may be invaluable. Incipient fires grow quickly into free burning fires.

History

• An older copper canister fire extinguisher.

  Fire extinguishers have been in existence since the early 1700s when decorative glass containers were used. Some of these were thrown at the fire, breaking the glass and releasing their agent. Others had a small chamber of gun powder and a fuse. Light the fuse, toss the container into the fire and wait. The small explosion would rupture the container and release the agent. It wasn't until the late 1800s that the pressurized canister was developed and used. The basic idea carries on today.

Function

• Dry powder agents stick to everything.

  Dry powder extinguishers are made to be used on A-B-C class fires or B-C class fires. They will also work on a kitchen grease fire. All extinguishers are made to suppress one side of the fire triangle; fuel, heat or oxygen. Dry powder smothers a fire, depriving it from oxygen and stopping the chemical reaction that allows a fire to continue to burn. The biggest drawback to these extinguishers is that they are extremely messy.

Multi-purpose Dry Chemical A-B-C

• Monoammonium phosphate is the chemical of choice for the A-B-C type extinguisher.

  The chemical used in this extinguisher type is monoammonium phosphate, a sticky yellow powder that is non-conductive, biodegradable and corrosive. This chemical is also used in flame retardants and fertilizers. It is non-hazardous yet does cause mild irritation to the skin and lungs with prolonged contact. OSHA lists this chemical as a possible carcinogen to humans. Monoammonium phosphate breaks the fire triangle by depriving the fire of oxygen.

General purpose dry powder B-C

• 88 percent of all kichen fires are related to cooking.

  This extinguisher type uses either sodium or potassium bicarbonate. These agents are non-hazardous, non-conductive and non-corrosive. Unlike the multipurpose dry chemical the general purpose powder is easily cleaned up by vacuuming. Sodium bicarbonate is also the main ingredient in baking soda. This is why some instructors and fire experts advocate pouring this substance over a small kitchen fire if nothing else is available. Bicarbonate type extinguishers break the fire triangle by depriving the fire of oxygen.

Conclusion

• Calling 911 is your best protection during a fire.

  Having the proper fire extinguisher/s in the home is as important as having working smoke detectors. Many insurance companies now give policy discounts for having fire extinguishers in the home. Local fire departments also provide fire extinguisher classes to ensure proper use and handling. Just remember, dry powder extinguishers provide excellent protection but they are not a substitute for the fire department.