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    Restaurant Cooking Areas Require Class K Extinguishers Too

    By Mark Conroy


    Years ago, sodium bicarbonate or potassium bicarbonate dry chemical fire extinguishers, with a minimum 40-B rating, were required in restaurant cooking areas. But they were inefficient when severe fire hazards were created by the use of hot-burning vegetable oil and energy-efficient cooking appliances. This made more effective portable extinguishers in commercial kitchens necessary.

    After substantial testing, a wet chemical extinguishing agent was introduced. This spawned wet chemical extinguishers that discharge a fine spray, providing several times the fire extinguishing capability of a 40-B rated sodium bicarbonate or potassium bicarbonate dry chemical extinguisher on a cooking oil fire.

    This prompted the development of a fire test protocol by Underwriters Laboratories (UL) and eventually the creation of a Class K rating and listing of those fire extinguishers. The Class K rating involves special tests on cooking appliances using cooking oil.

    Initially, NFPA updated the extinguisher standard NFPA 10 to allow the UL rated Class K extinguishers for these hazards. Later, they mandated that all 40-B rated sodium bicarbonate or potassium bicarbonate dry chemical extinguishers installed, specifically for the protection of cooking appliances, be removed from service. Today, only wet chemical extinguishers that are listed and labeled for Class K fires are permitted for the protection of commercial cooking operations.

    Restaurant cooking areas always need Class K extinguishers in addition to a wet chemical system. The codes are consistent in this area, as both NFPA 10 and NFPA 96 mandate extinguisher installation. The extinguishers are considered backups to the system. Restaurant owners should instruct employees to comply with the Class K placard, which says to trip the system before attempting to fight the fire with an extinguisher. Tripping the system cuts off the heat source to the appliances and allows them to cool below the re-ignition temperature. Once the system is tripped, extinguishers can be used on appliances and spot fires.

    It is important to remember that the maximum travel distance from any appliance to a Class K extinguisher is not permitted to exceed 30 feet.


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