When it comes to fire safety, not all classes of fires are the same. Different materials burn in different ways, which means the way you put out a fire depends on what’s actually burning. Using the wrong type of extinguisher or suppression system can make things worse—spreading flames, causing dangerous reactions, or even making the fire harder to control. That’s why fire protection professionals classify fires into different types, each requiring specific methods to detect, contain, and extinguish.
Whether you manage a commercial building, industrial facility, restaurant, or residential property, understanding these fire classifications can help you choose the right fire protection systems. In this guide, we’ll break down the five classes of fires—Class A, B, C, D, and K—along with the best fire detection and alarm, suppression, and extinguishing solutions for each. Knowing how to respond to different types of fires can make all the difference in protecting lives, property, and business operations.
Five Classes of Fires: What You Need to Know
Class A Fires – Common Combustibles Materials
Class A fires involve solid materials such as wood, paper, fabric, rubber, and some plastics. These fires are the most common of the classes of fires and typically occur in homes, offices, schools, and warehouses.
Detection & Alarm Systems:
- Smoke detectors (ionization or photoelectric) are the best choice, as they quickly detect smoldering or flaming fires involving solid combustibles.
- Heat detectors can also be used in dusty environments where smoke detectors may cause false alarms.
Fire Sprinklers & Suppression:
- Water-based fire sprinklers are the most effective and widely used solution for Class A fires, as water cools and suppresses the flames.
- Foam suppression systems may also be used in some settings where additional smothering is needed.
Fire Extinguishers:
- Class A extinguishers use water, foam, or dry chemical agents to smother the flames and cool down the material.
- Multipurpose ABC fire extinguishers are a convenient solution for areas where multiple fire risks are present.
Class B Fires – Flammable Liquids and Gasses
Class B fires involve flammable liquids or gases such as gasoline, alcohol, propane, butane, grease, oil-based paints, and solvents. These fires are commonly found in garages, laboratories, fuel stations, kitchens, and industrial facilities.
Common hazards include improperly stored cleaning chemicals in maintenance rooms, flammable liquids in laundry facilities, propane leaks from gas-powered equipment, and fuel spills in parking garages. When exposed to heat or sparks, these materials can ignite quickly, creating a dangerous situation. For a deeper dive into Class B fire risks and prevention strategies in residential facilities, check out our dedicated blog Preventing Class B Fires in Residential Facilities.
Detection & Alarm Systems:
- Flame detectors are highly effective at detecting fires fueled by flammable liquids or gases.
- Gas leak detection systems can help identify leaks early, preventing fires from starting in the first place.
Fire Suppression & Sprinklers:
- Foam suppression systems smother the flames and prevent vapors from reigniting.
- Dry chemical suppression systems (such as sodium bicarbonate or monoammonium phosphate) are also effective in confined areas.
Fire Extinguishers:
- Class B fire extinguishers use foam, dry chemical, or CO₂ to cut off oxygen and stop combustion.
- Carbon dioxide (CO₂) extinguishers are preferred in areas with sensitive equipment, as they leave no residue.
- Water should never be used on Class B fires, as it can cause the flammable liquid to spread.
Class C Fires – Electrical Fires
Class C fires involve electrical failures from appliances, wiring, circuit breakers, outlets, and electronic equipment. This class of fires are common in offices, server rooms, data centers, and industrial buildings.
Detection & Alarm Systems:
- Smoke detectors (ionization or photoelectric) work well in offices and residential spaces.
- Heat and flame detectors may be used in areas where smoke detection could cause false alarms.
Fire Suppression & Sprinklers:
- Clean agent suppression systems are ideal for protecting electronics, as they suppress fires without damaging equipment.
- CO₂ fire suppression systems can also be used in enclosed spaces where electrical fires are a concern.
Fire Extinguishers:
- Class C fire extinguishers use dry chemical or CO₂ to smother flames without conducting electricity.
- ABC fire extinguishers are commonly used for general-purpose electrical fire protection.
- Water should never be used on Class C fires, as it can cause electrocution or further electrical failures.
Class D Fires – Combustible Metals
Class D fires involve flammable metals such as magnesium, titanium, lithium, sodium, zirconium, and potassium. These fires are rare but extremely dangerous, often occurring in laboratories, metal processing plants, and manufacturing facilities.
Detection & Alarm Systems:
- Flame detectors are the most effective for spotting high-temperature fires in industrial environments.
Fire Extinguishers:
- Class D fire extinguishers use specialized dry powder agents, such as graphite, sodium chloride, or copper, to smother metal fires.
- These extinguishers must be applied carefully, as improper use can spread burning metal particles.
- Water, foam, CO₂, and standard dry chemical agents are ineffective against Class D fires.
Class K Fires – Kitchen Grease Fires
Class K fires involve cooking oils and fats, commonly found in commercial kitchens, restaurants, and cafeterias. These fires burn hotter and are harder to extinguish than standard grease fires.
In hospitals, nursing homes, schools, and other facilities, commercial kitchens operate with high heat, open flames, and grease buildup, creating a serious fire risk. A kitchen fire suppression system is essential to quickly extinguish grease fires, protect staff and occupants, and keep operations running smoothly. These systems are specially designed to handle the unique hazards of busy commercial kitchens, where traditional fire extinguishers or sprinklers may not be effective.
For more on this class of fire and how commercial kitchen fire suppression systems work, check out our blog post Introduction to Commercial Kitchen Fire Suppression Systems.
Detection & Alarm Systems:
- Flame and heat detectors are recommended for kitchen environments.
- Cooking equipment fire suppression systems automatically detect and suppress fires at the source.
Fire Suppression & Sprinklers:
- Wet chemical fire suppression systems (such as Ansul R-102 or Kidde systems) are designed specifically for commercial kitchens.
- These systems release a chemical agent that reacts with hot grease, cooling and forming a soapy layer that prevents re-ignition.
Fire Extinguishers:
- Class K fire extinguishers use wet chemical agents (such as potassium acetate) to neutralize burning oils and fats.
- ABC or CO₂ extinguishers should NOT be used, as they are ineffective against high-temperature cooking oil fires.
- Water should never be used on Class K fires, as it can cause the burning grease to splash and spread.
Be Prepared With the Right Fire Protection For Different Types of Fires
Each of the different classes of fire presents unique challenges, and having the correct fire detection, suppression, and extinguishing solutions is crucial for keeping people and property safe.
At International Fire Protection (IFP), we provide expert fire system design, installation, and maintenance to ensure your facility is protected against all different types of fires. Whether you need a water sprinkler system, a clean agent suppression system, or specialized fire extinguishers, our team can help you find the best solution for your needs.
Don’t wait until an emergency happens—be proactive and prepared! Contact IFP today to discuss fire protection solutions for your facility.
