Fire extinguisher is a fire safety requirement

Class K Fire Extinguishers: What's Inside and When to Use Them

Having a Class K fire extinguisher in any commercial building with a kitchen or cafeteria is not just a good idea but a legal obligation. These products are specifically designed to contain kitchen fires and snuff them out fast.

But with so many types of fires and different extinguishers for each one, how do you know when a Class K is the right option for you?

Here we’ll discuss the importance of a Class K fire extinguisher, who should have one, and how they work.

What Is a Class K Fire Extinguisher?

Red Class K fire extinguisher on kitchen counter beside stovetop

Understanding the classes of fire extinguishers can get confusing since they go from A, B, C, and D, then skip right to K.

Although it might seem like someone dropped the ball here, we have the explanation to help clear some things up.

There are five classes of fires:

  • Class A Fires: Ordinary solids (wood, clothes, paper, and some plastic)
  • Class B Fires: Flammable liquids and gas (oil, grease, ether, gasoline, and alcohol)
  • Class C Fires: Electrical (wiring, cooking appliances, etc.)
  • Class D Fires: Flammable metals (potassium, sodium, etc.)
  • Class K Fires: Cooking fires (fats and oils)

There are four types of extinguishers:

  • Type A: Pressurized water
  • Type ABC: Dry chemicals
  • Type BC: Carbon dioxide
  • Type K: For kitchen grease fires

The type of extinguisher is labelled to represent the fires they are equipped to put out.

Class K fire extinguishers are unique compared to the rest because they are designed to put out fires related to cooking and only cooking.

What Is Inside a Class K Fire Extinguisher?

Class K fire extinguishers are full of a wet alkaline mixture. The combination is typically some form of potassium acetate, potassium citrate, and potassium carbonate.

The active agent in Class K fire extinguishers creates a blanket of foam through saponification to keep the flames contained, stopping the opportunity for the fire to reignite by suffocating it.

Saponification is the term used to describe the reaction between the alkaline mix and fatty acids, creating a thick, soapy foam to absorb the heat elements.

The water content assists in lowering the temperatures of the flammable ingredients, keeping them below the ignition point.

The materials found inside other fire extinguishers are not equipped to handle Class K grease fires that originate from kitchen items. This is why these fires have an extinguisher explicitly designed for them.

Using Other Classes of Fire Extinguishers to Extinguish Class K Fires

You can use a Class K fire extinguisher on other types of fires. For example, a Class K fire spreads throughout the kitchen, igniting materials on the Class A list.

However, you should never try to use another type of fire extinguisher to put out Class K fires. These options will not work to fight fat and cooking oil, and some could make things even worse.

When Should You Use Class K Fire Extinguishers?

News coverage of large kitchen fire on stovetop

Class K fire extinguishers are mandatory for commercial properties. Employers are required to provide Class K fire extinguishers to any building where a Class K fire has the potential for breaking out.

Occupational Safety and Health Administration (OSHA) set and enforced these rules as part of public and workplace safety guidelines to ensure every work environment has the proper equipment in dangerous situations.

Where Class K Fire Extinguishers Are Kept

The primary locations for finding a Class K fire extinguisher are kitchens, cafeterias, and dining halls. Currently, there are no specific requirements regarding the distance between each extinguisher, like for other types.

However, each Class K extinguisher must be easy to locate and access immediately.

Some ideal locations for Class K fire extinguishers include:

  • On cabinets or shelves located near the cooking space
  • On the wall, hanging from an attachment
  • On a hanger close to the fire source
  • On top of the refrigerator if it is in easy reach

Places to never put a Class K fire extinguisher:

  • Inside a cabinet with closed doors
  • Closed in any space requiring a key to open
  • Directly near cooking appliances or areas with open flames
  • Far away from the point of anticipated ignition

Class K fire extinguishers should always be set up in culinary schools, school cafeterias, hospital cafeterias, or other commercial buildings that have kitchens and are at risk for oil and fat-fueled fires.

Height Requirements for Class K Fire Extinguishers

The height level you must place a Class K fire extinguisher depends on the product's weight.

If the extinguisher weighs less than forty pounds, it shouldn’t sit any higher than five feet off the ground.

If the extinguisher weighs more than forty pounds, it shouldn’t sit more than 3.5 feet off the ground.

Using a Class K Fire Extinguisher (PASS)

You would use a Class K fire extinguisher the same way you would use any other type. The most common operation requires users to follow the PASS technique.

  • P- Pull the pin. Break the tamper-proof seal by pulling out the pin of the extinguisher.
  • A- Aim the extinguisher low, pointing the nozzle to the base of the fire.
  • S- Squeeze the handle. Apply firm pressure to release the mist that puts out kitchen fires.
  • S- Sweep the nozzle, moving in a side-to-side motion to cover as much area as possible.

Inspections and Maintenance for Class K Fire Extinguishers

You must keep your fire extinguishers in working condition, having maintenance and inspections done by professionals at least once a year, more if circumstances permit.

Employees must keep good records of maintenance and inspections, including the dates, jobs completed, etc.

Adding a Fire Suppression System

Fire suppression systems are more than just fire alarm systems. These systems are highly sensitive, detecting smoke and heat as soon as it starts. Once detected, an alarm will go off, and the appropriate extinguishing agent is automatically released.

Final Thoughts

A Class K fire extinguisher is crucial for public safety in commercial buildings. These fire extinguishers are the best option for fighting kitchen fires, starting from high heat levels in oils and other ingredients.

Knowing how to use these fire extinguishers and when to use them can keep you and everyone else in the building safe if a kitchen fire erupts.

Back to blog