Importance of Class K Fire Extinguishers

Restaurant kitchen fires can lead to employee and customer injuries, total destruction of your building, and may place a significant financial burden on your business until operations are restored. From 2007 to 2011, the National Fire Protection Association (NFPA) has reported 32,272 non-residential cooking equipment fires which have resulted in 21 fatalities, 428 injuries and $185 million in property damage.

What is a Class K Fire?

The NFPA describes class K fires as those fires that involve combustible cooking materials such as vegetable oils that are used in cooking operations. These types of fires tend to spread rapidly and can result in injuries and massive building damage.

Kitchen fire risks changed when restaurants adjusted their practices from cooking with lard to vegetable oils, and cooking equipment started to become more efficient. In 1994, Underwriters Laboratories (UL) found that existing dry chemical fire extinguishing agent was failing to cool the vegetable oils below their 685⁰F auto-ignition temperatures. The dry chemical formed a layer of soap on the fire to suppress the fire, however this soap layer broke down rapidly due to the higher temperature of vegetable oil fires and then failed to suppress the fire. Wet chemical fire extinguishing agent was developed to be more effective at cooling the fire below the auto-ignition temperatures. This wet chemical is the extinguishing agent used in Class K portable fire extinguishers and UL 300 Automatic Extinguishing Systems (AES).

Video [1:40]: Using a Class K Fire Extinguisher 

Why Do You Need Both an AES and a Class K Portable Fire Extinguisher?

The AES is the primary fire suppression system for a fire located under its area of coverage. Once a fire has started, the AES would be automatically activated or manually activated from the pull station. When the AES is activated, it will shut off the power/fuel sources to the cooking equipment and dispense the wet chemical agent over the fire. If the fire is located outside of the AES coverage area, then the portable K fire extinguisher would be the only option for additional fire suppression. The NFPA and Society Insurance require that both a UL 300 AES and Class K fire extinguishers are in place and properly maintained to ensure readiness in the event of a fire. The AES and the Class K fire extinguisher are designed to work together to provide fixed and portable fire suppression.

What to Do In the Event of a Kitchen Fire

In the event of a kitchen fire, Society Insurance recommends the immediate evacuation of employees and customers to the nearest gathering point outside of the building. Regardless of the size of the fire, immediately activate any alarm systems to notify the building occupants to evacuate. Immediately call 911 from a safe location to notify the nearest fire department to initiate their response. The safety of employees and guests should always take precedence over fighting a fire. If a portable Class K fire extinguisher is to be used, refer to the Society Insurance blog “How to use a Fire Extinguisher: an Easy 4-Step Process” for the proper steps to use a fire extinguisher.

Installation Requirements of a Class K Fire Extinguisher

Due to the rapid expansion that Class K fires present, it’s required to install portable Class K fire extinguishers no further than 30 feet from all cooking equipment that uses vegetable oils. The extinguisher must be visible with the instruction label also visible while mounted. It is essential to ensure that employees do not hang items on the extinguisher and that they are properly mounted in their designated places.

After being mounted and placed into service, Class K portable fire extinguishers need to be visually inspected monthly to ensure that they are in proper working condition.

This monthly inspection should be performed visually for the following items:

  1. Located in a designated place
  2. Visibility or means of identifying the location
  3. Easy access
  4. Pressure gauge reading in the green range
  5. Good condition of the nozzle and hose
  6. The safety pin should be in place
  7. Verify that annual maintenance has been performed by a qualified professional fire extinguisher service provider and documented with a tag showing the date of the annual maintenance

Learn more about fire safety training and protecting your business with the free resources in this Fire Prevention blog series or download this free whitepaper: “Identify and Eliminate Restaurant Fires.” Please contact your local Society agent to discuss more about fire safety at your business.

Additional Resource:

NFPA 10: 


Greg joined Society Insurance in 2018 as a Risk Control Representative. Prior to that, he served fourteen years in the U.S. Air Force as a Fuels Specialist. His duties included the role of Safety Manager for his unit with oversight of petroleum and logistics operations. Greg earned his A.S. degree in Logistics from Community College of the Air Force and is currently pursuing his bachelor's degree in Safety Management at Indiana State University.

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