• Restaurants: Servicing Class K Extinguishers

    Class K fire extinguishers are the preferred type of extinguisher for restaurant cooking areas. The wet chemical extinguishing agent is discharged as a fine mist spray, which does not splash the oil and spread the fire. When the agent is applied to a cooking oil fire, there is rapid fire extinguishment and a thick foam blanket is created, which prevents re-ignition. There is good visibility during fire fighting, and cleanup is minimal after extinguishment. For these reasons, extinguishers with a Class K rating are required to be installed in cafeteria and restaurant cooking areas where cooking oil is used. Here is what you need to know to keep these extinguishers safe and operational.

    Placement of Extinguishers and Placards

    Class K fires are fires in cooking appliances that involve cooking oils [10, 5.2.5]. When you service these extinguishers, you need to make sure there are a sufficient number of extinguishers to protect the hazards. That means a Class K extinguisher needs to be no further than 30 ft from any cooking operations [10, 6.6.2]. For large commercial kitchens, several Class K extinguishers may be needed to comply with this requirement. Also solid fuel cooking (5 ft or less) is required to have either a 2-A water extinguisher or a Class K extinguisher within 20 ft of the appliance [10, 6.6.3 and 96, 14.7.8]. Where a hood system is installed, a placard needs to be in place that says the kitchen system needs to be operated first [10. and 96, 10.2.2].

    Monthly Inspections and Annual External Maintenance

    Class K extinguishers are required to be inspected on a monthly basis [10,]. Class K extinguishers also require an annual external visual examination [10,]. These extinguishers do not require an annual internal examination [10,]. Any deficiencies found during the external examination require immediate corrective action [10, 7.3.5]. A service tag is required after completion of the work [10,].

    Periodic Hydrostatic Testing and Internal Examination

    Class K extinguishers are required to be hydrostatically tested every 5 years [10, 8.3.1]. Prior to the test, an internal examination is required [10,]. The wet chemical extinguishing agent is not permitted to be reused [10,], so the existing agent is discarded and new agent is required to be installed after the test [10,]. Extinguisher manufacturers use different Class K extinguishing agent formulations, so the agent cannot be substituted [10,]. Only the agent specified on the extinguisher nameplate is permitted to be used for recharging [10,]. Another important safety provision is that only the type of expellant gas specified on the nameplate is permitted to be used [10,].


    A label is required to be installed on extinguishers that pass the hydrostatic test [10,]. Although Class K extinguishers are not required to have a service collar installed during initial field charging [10,], a collar is required after internal examination and hydrostatic testing [10,].

    Class K extinguishers are critically important to ensure safety for commercial cooking operations. Performing servicing, according to code, will help keep these extinguishers operational and your customer code compliant.

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    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.