What Are the 5 Different Classes of Fires?

Posted by Adam Joones on December 9th, 2023

While fire can seem like one big threatening force, it’s important to know that there are actually several classes of fires. Fires are classified into different categories based on the materials they involve and knowing these classes is crucial for choosing the right extinguishing method and equipment. 

“Nearly 60% of businesses never recover after a fire. Make sure yours isn’t one of them”. London Fire Brigade

Class A Fire: Combustibles

Class A fires involve combustible materials such as wood, paper, cloth, and plastics. To extinguish these fires effectively:

• Use water or foam-based extinguishers. Water cools the fire while foam suffocates it by creating a barrier between the fuel and oxygen.

• Smother the flames with a fire blanket for smaller incidents involving cloth or paper.

Class B Fire: Flammable Liquids/Gases

Class B fires involve flammable liquids like gasoline, oil, grease, or gases like propane. To extinguish these fires effectively:

• Use dry chemical or carbon dioxide (CO2) extinguishers. Dry chemical agents smother the fire, while CO2 removes oxygen and cools the fire.

• Never use water on a Class B fire, as it can spread the flames.

Class C Fire: Electrical Equipment

Class C fires involve electrical equipment, wiring, or outlets. For these fires:

• Use CO2 or dry powder extinguishers. CO2 displaces oxygen, and dry powder works to smother the fire.

• Always de-energize the electrical source before attempting to extinguish the fire to prevent electrocution.

Class D Fire: Combustible Metals

Class D fires involve combustible metals like magnesium, titanium, or potassium. Tackling such fires requires specialised extinguishing agents:

• Use dry powder agents specifically designed for metal fires.

• These fires are rare but extremely dangerous. Evacuate the area and call emergency services immediately.

Class K Fire: Cooking Oils/Fats

Class K fires involve cooking oils and fats commonly found in kitchens: To extinguish these fires effectively:

• Use wet chemical extinguishers designed for Class K fires. These agents cool the fire and create a barrier on the surface of the oil, preventing reignition.

• Never use water, as it can cause the oil to splatter and spread the fire.

In conclusion, understanding the different classes of fires and the appropriate extinguishing methods is crucial for fire safety. Being equipped with the right knowledge and tools can prevent minor incidents from escalating into major disasters.

Remember, safety is paramount. Always prioritise personal safety and evacuate if a fire becomes uncontrollable. 

Find out more about the types of fire extinguishers and when to use them, or carry out a  fire risk assessment  for your business.