A fire may look similar from a distance, but not every fire should be extinguished in the same way. The material that is burning determines the class of fire, and choosing the wrong extinguishing agent can make the situation more dangerous.
Understanding Class A, B, C, D, and K fires helps building occupants, facility managers, and safety teams select the right fire extinguisher and respond appropriately during the early stages of a fire.
In India, IS 2190:2024 defines Class A, B, C and D fires and identifies cooking-oil and fat fires as Class F. Internationally, particularly under NFPA terminology, cooking-oil and fat fires are referred to as Class K. (Bureau of Indian Standards)
Important: A portable fire extinguisher is intended for fires of limited size. If a fire is growing rapidly, producing heavy smoke, or cannot be safely approached, evacuate immediately and call the fire service rather than attempting to fight it yourself. (Bureau of Indian Standards)
What Are the Different Classes of Fire?
| Fire Class | What Is Burning? | Common Examples | Typical Extinguishing Approach |
| Class A | Ordinary solid combustibles | Wood, paper, cloth, rubber, some plastics | Water, foam, ABC dry chemical |
| Class B | Flammable liquids | Petrol, diesel, paints, solvents, oils | Foam, dry chemical, suitable clean agents |
| Class C | Flammable gases under pressure in India / energized electrical equipment under NFPA | LPG, CNG / electrical panels and equipment | Suitable dry chemical or other approved agent |
| Class D | Combustible metals | Magnesium, sodium, potassium, aluminium | Special Class D extinguishing media |
| Class K | Cooking oils and fats | Deep-fat fryers, commercial cooking equipment | Wet chemical / approved kitchen-fire extinguisher |
Note: Fire classifications differ between standards and regions. For example, IS 2190:2024 uses Class C for flammable gases under pressure and Class F for cooking media, while NFPA uses Class C for energized electrical equipment and Class K for cooking oils and fats. Always follow the classification and extinguisher markings applicable to your location and equipment.
Class A Fire: Ordinary Combustible Materials
What is a Class A fire?
Class A fires involve ordinary combustible solid materials. Common examples include:
- Wood
- Paper
- Cardboard
- Cloth
- Rubber
- Some plastics
- Furniture
These materials generally leave glowing embers or ash after burning.
According to IS 2190:2024, the cooling effect of water is essential for extinguishing Class A fires.
How do you fight a Class A fire?
For a suitable, limited Class A fire, commonly approved options include:
- Water extinguishers
- Foam extinguishers
- ABC dry chemical extinguishers
The objective is primarily to cool the burning material and stop re-ignition.
Everyday example
A waste-paper bin catches fire because of an ignition source. If the fire is still small and there is a suitable extinguisher nearby, a correctly rated extinguisher may be used.
Class B Fire: Flammable Liquid Fires
What is a Class B fire?
Class B fires involve flammable liquids or liquefiable solids. Examples can include:
- Petrol
- Diesel
- Solvents
- Paints
- Certain oils
- Flammable chemicals
IS 2190:2024 states that a blanketing effect is important for extinguishing Class B fires.
How do you fight a Class B fire?
Depending on the specific fuel and extinguisher approval, suitable agents may include:
- Foam
- Dry chemical powder
- Certain clean agents
The extinguisher should be specifically rated for Class B fires.
What should you avoid?
Do not automatically use water on a flammable-liquid fire. A water stream can spread some burning liquids and make the fire worse.
Everyday example
A small spill of flammable liquid catches fire in a workshop. The correct response requires an extinguisher approved for that particular hazard—not simply whichever extinguisher happens to be closest.
Class C Fire: Know Which Classification Your Standard Uses
Class C is particularly important because the meaning of Class C differs between fire-safety standards.
Under IS 2190:2024
Class C refers to fires involving flammable gases under pressure, including liquefied gases. Examples may include gases such as LPG and similar fuel gases.
For these fires, the burning gas must be controlled using an appropriate extinguishing medium and, where possible, the fuel supply should be safely isolated.
Under NFPA terminology
NFPA classifies energized electrical equipment fires as Class C. Examples include:
- Electrical panels
- Motors
- Switchgear
- Computers
- Electrical appliances
The important point is that the electrical hazard remains energized until power is disconnected.
NFPA also notes that a Class C rating is applied to extinguishers that already have an appropriate Class A or B rating and have been tested for electrical conductivity.
How should electrical fires be handled?
Where energized electrical equipment is involved, use an extinguisher specifically approved for electrical hazards under the applicable standard.
Common extinguisher types may include:
- CO₂ extinguishers
- Suitable dry chemical extinguishers
- Certain clean-agent extinguishers
Never use water on energized electrical equipment.
Once electrical power has been safely isolated, the remaining burning material may fall under another fire class.
Class D Fire: Combustible Metal Fires
What is a Class D fire?
Class D fires involve combustible metals.
Examples include:
- Magnesium
- Sodium
- Potassium
- Zinc
- Certain aluminium applications
These fires are generally found in specialized industrial environments such as metal processing and manufacturing facilities.
IS 2190:2024 specifically notes that Class D fires require special media and techniques because certain burning metals can react with commonly used extinguishing agents. How do you fight a Class D fire?
Use a specialized Class D fire extinguisher or extinguishing medium selected for the specific metal involved.
There is no single universal agent that should automatically be used for every combustible-metal fire.
What should you avoid?
Do not experiment with water or a standard ABC extinguisher unless the equipment is specifically approved for the particular metal hazard.
Class D fires should generally be handled by trained personnel with appropriate equipment and procedures.
Class K Fire: Cooking Oil and Fat Fires
What is a Class K fire?
Class K fires involve cooking oils and animal or vegetable fats, particularly in commercial kitchens.
Typical locations include:
- Restaurants
- Hotels
- Canteens
- Food-processing facilities
- Commercial kitchens
NFPA identifies these as Class K fires.
In India, IS 2190:2024 uses the designation Class F for fires involving cooking media such as vegetable or animal oils and fats.
How do you fight a cooking-oil fire?
Use a suitable wet-chemical or other approved kitchen-fire extinguishing system/extinguisher designed for cooking-oil hazards.
These systems are designed to suppress the fire and help prevent re-ignition.
What should you never do?
Never throw water onto a burning pan of cooking oil.
Water can rapidly turn into steam and violently disperse burning oil, causing the fire to spread.
If safe to do so, switch off the heat source and use the appropriate kitchen-fire protection equipment. Do not move a burning pan or attempt to carry it outside.
Why Choosing the Right Fire Extinguisher Matters
A fire extinguisher is not a universal solution for every type of fire.
For example:
- Water can be effective for many Class A fires but can be dangerous on energized electrical equipment or certain flammable-liquid fires.
- Foam can be suitable for certain Class A and Class B hazards but is not automatically appropriate for every fire.
- ABC dry chemical powder can cover multiple fire hazards, but it is not a substitute for specialized Class D or kitchen-fire protection.
- CO₂ can be useful for certain electrical and flammable-liquid hazards, but it does not provide the same cooling effect as water on ordinary combustibles.
- Wet chemical systems/extinguishers are designed specifically for cooking-oil and fat hazards.
NFPA emphasizes that a portable extinguisher must match the fire it is intended to fight.
How to Choose the Right Fire Extinguisher
Before selecting a fire extinguisher, consider:
1. Identify the fuel
Ask: What can burn in this area?
Is it paper and wood, flammable liquid, gas, electrical equipment, combustible metal, or cooking oil?
2. Check the extinguisher rating
Do not select an extinguisher based only on its size or appearance.
Check the fire-class markings and ratings on the extinguisher.
3. Consider the environment
An office, kitchen, electrical room, workshop, chemical storage area, and manufacturing plant may require very different fire-protection arrangements.
4. Follow applicable standards
Fire extinguisher selection, installation, inspection, maintenance, and testing should follow the applicable standards and the requirements of the local authority having jurisdiction.
In India, IS 2190:2024 provides requirements for the selection, installation, maintenance, and testing of portable and mobile fire extinguishers.
Can One Fire Extinguisher Handle Multiple Fire Classes?
Yes, some extinguishers are designed and tested for multiple fire classes.
For example, ABC dry chemical extinguishers can be suitable for Class A, B, and electrical hazards where they carry the appropriate ratings.
However, multi-purpose does not mean universal.
A standard ABC extinguisher should not simply be assumed to be suitable for:
- Combustible metal fires
- Commercial cooking-oil fires
- Every chemical fire
- Every specialized industrial hazard
The extinguisher must carry the appropriate certification and rating for the hazard.
Fire Class vs. Fire Extinguisher: A Quick Guide
| Fire Type | Typical Fuel | Common Protection Approach |
| Class A | Wood, paper, cloth, rubber, plastics | Water / Foam / ABC |
| Class B | Petrol, solvents, paints, flammable liquids | Foam / Dry Chemical / suitable clean agent |
| Class C – IS 2190 | Flammable gases under pressure | Suitable dry chemical or approved agent; isolate fuel when safely possible |
| Class C – NFPA | Energized electrical equipment | CO₂ / Dry Chemical / suitable clean agent |
| Class D | Combustible metals | Specialized Class D media |
| Class K – NFPA / F – IS 2190 | Cooking oils and fats | Wet chemical / approved kitchen-fire protection |
The exact extinguisher type and rating should always be selected according to the hazard, applicable standard, manufacturer certification, and site requirements.
What to Do Before Using a Fire Extinguisher
Only attempt to extinguish a small, developing fire if:
- You have been trained or are confident using the extinguisher.
- The correct extinguisher is available.
- The fire is still limited in size.
- You have a clear escape route behind you.
- Smoke and heat conditions allow you to approach safely.
- Emergency assistance has been called where required.
If any of these conditions are not met, evacuate instead of fighting the fire.
Final Takeaway
Knowing the difference between Class A, B, C, D, and K fires can help prevent a dangerous mistake during an emergency.
The most important rule is simple:
Identify what is burning → choose the correctly rated extinguisher → use it only when the fire is small and safe to approach.
Remember that fire classifications vary by standard. In India, IS 2190:2024 uses Class F for cooking-media fires and Class C for flammable gases, while NFPA uses Class K for cooking-media fires and Class C for energized electrical equipment. Always check the applicable standard and extinguisher label rather than relying on the letter alone. For offices, factories, warehouses, commercial kitchens, residential buildings, and other facilities, proper fire extinguisher selection, placement, inspection, maintenance, and training are essential parts of an effective fire-safety program.
Need help selecting the right fire extinguishers for your facility? A professional fire-safety assessment can identify the fire hazards present and help determine the appropriate fire protection equipment and systems.