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    Extinguishers: Facts About Fire Extinguishers

    By Mark Conroy

    Fire extinguishers are to be used immediately when a fire is discovered. They are most effective early, when the fire is small, with little heat. Safety in the area is maintained, because the fire does not spread, and the generation of toxic products is stopped. Extinguishers are placed and mounted for quick response to a fire. Mounting locations are selected for easy accessibility and quick removal. Technicians determine the type and size to match potential fires. Extinguishing agent selection is also a prime factor. Here are the common types to help your customers understand their importance.

    Dry Chemical Extinguishers leave a residue, which must be cleaned up after any discharge.

    • Multipurpose Dry Chemical Extinguishers are installed throughout buildings for Class A common combustibles. Travel distance from any point to an extinguisher is 75 ft.
    • Ordinary Dry Chemical Extinguishers are installed for potential flammable liquid fires. Travel distance from a hazard is 30 ft with smaller extinguishers and 50 ft for larger extinguishers.
    • Purple K Dry Chemical (PKP) Extinguishers contain the most effective agent for flammable liquid fires (quick knockdown and control), so less extinguishing agent is needed to extinguish a fire.
    • High-Flow Dry Chemical Extinguishers have a higher flow rate and discharge the agent quicker. They are installed for flammable liquids in motion and where obstacles are in the way.

    Foam Extinguishers are effective on flammable liquid fires in dip and quench tanks, fuel storage with dikes, or fuel spills. Foam blankets the entire surface and excludes air.

    A Pressurized Water Extinguisher contains 2 ½ gallons of tap water, under pressure, for use on common combustible fires. The water soaks and cools the burning materials, which prevents rekindling.

    Loaded Stream Extinguishers are water extinguishers with an anti-freeze additive. The additive is called a “loaded stream charge”, so they are often called loaded stream extinguishers.

    Water Mist Extinguishers contain de-ionized water, which does not conduct electricity. They have a special nozzle to deliver the water as a fine mist spray. They are effective on common combustibles.

    Clean Agent Extinguishers use Halon 1211 or a halocarbon. Halon 1211 depletes the earth’s ozone layer, so these extinguishers are only for critial applications. Halon 1211 and Halotron® I leave no residue and are used on electronic equipment.

    Carbon Dioxide Extinguishers are rated for flammable liquid fires but are also effective on common combustibles. When discharged, the liquid carbon dioxide flashes to a gas, so they have a short range.

    Class K Extinguishers contain wet chemical. They are installed in commercial kitchens for appliance fires involving cooking oil. A placard is installed to warn that the extinguishing system is to be discharged first.

    Dry Powder Extinguishers have a Class D rating, so they are intended for combustible metal fires only. They are installed in metal fabrications shops for fires involving metal filings, chips, and shavings.

    These are brief descriptions and not comprehensive. They are handy reminders of common fire extinguishers installed for safety and property protection.

    It is good to remind your customers that extinguishers are essential and are independent of a building’s automatic fire sprinkler system or other fixed protection. When a fire breaks out, grabbing the nearest extinguisher, and using it, will result in safety of personnel and continuation of business operations, with little interruption.

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    Mark Conroy is an engineer in our Boston, MA office.   © 2019 Brooks Equipment

    Disclaimer: The opinions expressed in the above Tech Series article are the author’s only and provide limited information. Although the information is believed to be reliable, Brooks Equipment Company, LLC expressly disclaims any warranty with respect to the information and any liability for errors or omissions. The user of this article or the product(s) is responsible for verifying the information’s accuracy from all available sources, including the product manufacturer. The authority having jurisdiction should be contacted for code interpretations.