Fire safety is one of the most important aspects of any building or workplace. However, not all fires are the same — and the measures to extinguish them differ accordingly. Understanding the different classes of fire and knowing which extinguisher to use in each situation can prevent property damage, save lives, and ensure compliance with fire safety regulations.
In this guide, we’ll explain the classifications of fire, highlight common causes, and discuss the appropriate extinguishers for each type.
Understanding Fire Classes
Fires are classified based on the type of fuel involved. Each class requires a specific type of extinguishing agent to safely control or put out the fire. In India, fire classes follow IS 15683 standards, similar to international guidelines, ensuring consistency across buildings and workplaces.
Here are the main fire classes:
1. Class A – Fires Involving Ordinary Combustibles
Class A fires involve ordinary solid materials that burn easily, such as paper, wood, cloth, plastics, and rubber. These fires are the most common in homes, offices, schools, and warehouses.
Extinguishers to Use: Water extinguishers, foam fire extinguishers, or dry chemical powder (DCP) extinguishers work best on Class A fires. Water cools the fire and reduces its heat, while foam and DCP smother the flames and prevent re-ignition.
Important Tip: Never use CO₂ extinguishers on Class A fires as they may not cool the burning material effectively.
2. Class B – Fires Involving Flammable Liquids
Class B fires occur when flammable liquids like petrol, diesel, oils, paints, or solvents catch fire. These fires are extremely dangerous because liquids can spread quickly, increasing the fire hazard.
Extinguishers to Use: Foam fire extinguishers, dry chemical powder extinguishers, and CO₂ extinguishers are suitable for Class B fires. Foam forms a barrier over the liquid, preventing oxygen from feeding the fire. DCP interrupts the chemical reaction, and CO₂ suffocates the flames without leaving residue.
Important Tip: Never use water-based extinguishers on flammable liquids, as water can spread the fire and worsen the situation.
3. Class C – Fires Involving Gases
Class C fires are caused by combustible gases such as LPG, propane, methane, or natural gas. These fires are particularly hazardous in industrial setups, kitchens, and laboratories. Gas fires can cause explosions if handled incorrectly.
Extinguishers to Use: Dry chemical powder extinguishers are the most effective for Class C fires. They interrupt the chemical reaction of the fire, stopping flames quickly. CO₂ extinguishers may also be used in certain controlled environments.
Important Tip: Do not attempt to extinguish a gas leak fire without shutting off the gas supply if it’s safe to do so. Always maintain a safe distance.
4. Class D – Fires Involving Combustible Metals
Class D fires occur when metals such as magnesium, sodium, potassium, titanium, or aluminium catch fire. These fires are more common in industries, laboratories, and workshops that handle metal powders or shavings.
Extinguishers to Use: Class D fires require specialized dry powder fire extinguishers designed for metal fires. These extinguishers smother the fire without reacting violently with the burning metal.
Important Tip: Never use water or standard extinguishers on metal fires, as these can cause explosions or spread molten metal.
5. Class K (or F) – Fires Involving Cooking Oils and Fats
Class K fires (also called Class F in some standards) are kitchen fires caused by cooking oils or fats. They are common in restaurants, hotels, and commercial kitchens. These fires burn at extremely high temperatures and can re-ignite if cooled improperly.
Extinguishers to Use: Wet chemical extinguishers are specifically designed for Class K fires. The chemical agent reacts with hot oils to form a thick soapy layer, a process called saponification, which cools the fire and prevents re-ignition.
Important Tip: Do not use water or CO₂ extinguishers on cooking oil fires, as they can cause splattering and spread the fire.
How to Choose the Right Fire Extinguisher
Choosing the correct extinguisher depends on the fire class, location, and environment. Some tips for selecting the right fire extinguisher include:
- Conduct a risk assessment to determine potential fire hazards in your property.
- Install multi-purpose dry chemical extinguishers in areas with multiple fire risks.
- Ensure extinguishers are IS ISO certified and comply with local fire safety regulations.
- Place extinguishers in accessible locations, clearly marked and easy to reach during emergencies.
For example, offices and homes generally need water or foam extinguishers for Class A fires, while industrial spaces may require DCP extinguishers for Class B and C fires. Kitchens need wet chemical extinguishers for oil fires.
Fire Extinguisher Maintenance and Safety Tips
Even the right extinguisher is useless if it’s not properly maintained. Regular inspections and servicing ensure that your extinguishers work when needed most. Key maintenance tips include:
- Check the pressure gauge and make sure it is within the safe range.
- Inspect for signs of corrosion, leakage, or damage.
- Ensure labels and instructions are legible.
- Refill extinguishers after every use, even if only partially discharged.
- Conduct annual inspections and servicing with certified fire safety professionals.
Conclusion
Understanding the different classes of fire and knowing which extinguisher to use is essential for building safety. From Class A fires involving paper and wood to Class K kitchen fires, each type of fire requires a specific extinguishing agent. Using the right extinguisher reduces the risk of injury, prevents property damage, and ensures compliance with safety regulations.
Investing in high-quality, certified extinguishers and maintaining them regularly is just as important as knowing how to use them. If you’re unsure about your building’s fire safety needs, consult a professional fire safety company like Naman Fire Engineers, offering installation, fire extinguisher refilling, and maintenance of all types of fire extinguishers across India.
By understanding fire classes and extinguisher types, you’re taking a critical step toward effective fire safety and preparedness.
