Ordinary men might think that fires are all the same. However, the truth is, they are categorized into different classes, and different types of extinguisher (e.g. Water-based fire extinguisher, dry and wet chemical fire extinguisher) are used to put them out.

In this article, we’re particularly discussing Class K fires and how to extinguish them safely.

What are Class K Fires

Ordinary combustibles like paper and wood belong to Class A Fires, while flammable liquids belong to Class B. Class C refers to fires that involve electrical equipment. Class D, on the other hand, are fires in combustible metals.

Technically, Class K fires — those that involve cooking oils and greases — are a subcategory of Class B fires because they involve flammable liquids. But as they feature some characteristics different from other flammable liquids, they’ve been considered as a separate fire class.

In 2017, statistics have shown that around 7,000 people get injured in kitchen fires every year. These fires are most often caused by the following highly flammable substances:

Vegetable oil

Olive oil



Bacon grease


How to Extinguish Class K Fires

As stated above, different fire extinguishers (e.g. Water-based fire extinguisher, dry and wet chemical fire extinguisher) are used to combat different fire classes. Nonetheless, one type of extinguisher can be used to smother more than one class of fire.

Class K Fires at Commercial Kitchens. Class K fire extinguishers are hailed as the best ones to suppress commercial kitchen fires. They act as reliable auxiliary gears for automated kitchen-specific fire protection systems.

But how do they work? This type of extinguisher uses the principle of saponification where alkaline mixtures are poured out to get involved with the burning cooking oil or grease. The reaction upon the mingling of the said substances create a soapy foam layer. This particular layer will then hold the vapor, cooling down and eventually suppressing the fire.

Before dry chemical K-class extinguishers are used to smother commercial kitchen fires. But with culinary innovations, the capacity of these extinguishers has decreased throughout the years. Now, they only create weak foam layers that fail to let kitchen fires die down.

As a solution, manufacturers have built a wet chemical fire extinguisher that can specifically put out kitchen fires. This extinguisher contains wet chemical agents that are alkaline in nature. Stronger than their dry chemical counterpart, these agents create a more resilient foamy layer that can allow the complete cooling down of the fire.

In addition, wet chemical fire extinguishers also result in reduced damage to the kitchen appliances involved.

Class K Fires at Residential Spaces. Class K fires don’t only take place at a commercial establishment, they can also occur at homes.

While restaurant kitchen fires use wet chemical K-class fire extinguisher, most homeowners rely on water mist fire extinguishers protect their properties from Class K fires.

This type of extinguisher uses water droplets as the fire-suppressing agent. It is also safe to use against Class A, B, and C fires, and fires that involve electrical equipment not more than 1,000 volts.

It is important to have the right fire extinguisher for the kind of fire you have to put out. If you need a wet chemical fire extinguisher, contact Westminster Fire Extinguisher Service today.