Introduction
Fire extinguishers are an important part of workplace fire safety and emergency preparedness. When a small fire starts, the right extinguisher can help bring it under control before it becomes a more serious incident, protecting people, property and business operations. Knowing which extinguisher to use for each fire risk is therefore essential for a safe and effective response.
This guide explains the different types of fire extinguishers, their uses, fire classes, how to choose the right fire extinguisher and basic fire extinguisher safety practices.
What Is a Fire Extinguisher?
A fire extinguisher is a portable firefighting device used to control or extinguish a small fire at an early stage, when it is safe to do so. It contains an extinguishing agent, such as water, foam, dry powder, carbon dioxide (CO₂), or wet chemical, which is released onto or around the fire to control it.
Using the correct fire extinguisher for the type of fire is important. An unsuitable extinguisher may fail to control the fire and, in some situations, can make the fire more dangerous.
How Does a Fire Extinguisher Work?
A fire needs heat, fuel and oxygen to start and continue burning. These three elements are known as the fire triangle. Combustion is also sustained by a chemical chain reaction; together, these four elements form the fire tetrahedron.
A fire extinguisher works by disrupting one or more of these elements. Depending on the extinguishing agent, it may:
- ✓ Remove heat by cooling the burning material.
- ✓ Reduce or separate oxygen from the fuel.
- ✓ Interrupt the chemical chain reaction that keeps combustion going.
Once the conditions needed for combustion are sufficiently disrupted, the fire can be controlled or extinguished.
The exact method depends on the extinguishing agent, which is why it is important to use the correct extinguisher for the specific fire risk.
Fire Classes Explained
Understanding fire classes helps you identify the type of fire and select an appropriate fire extinguisher. The table below provides a practical guide to common fire classes and risks.
| Fire Class / Risk | Type of Fire | Common Examples | Suitable Fire Extinguisher |
|---|---|---|---|
| Class A | Solid combustible materials | Wood, paper, cardboard, cloth and some plastics | Water, Foam, Water Mist or suitable ABC Dry Powder |
| Class B | Flammable liquids or liquefiable solids | Petrol, diesel, paint, solvents and similar materials | Foam, Dry Powder or CO₂, depending on the fire rating |
| Class C | Flammable gases under pressure | LPG and other flammable gases | Dry Powder, where appropriately rated |
| Class D | Combustible metals | Magnesium, aluminium, sodium and other reactive metals | Specialist Class D Dry Powder |
| Electrical Fire Risk | Fire involving energised electrical equipment | Electrical panels, wiring, computers and machinery | CO₂ or another appropriately approved non-conductive extinguishing agent |
| Class F / K | Cooking oils and fats | Deep-fat fryers and cooking oil or fat in kitchens | Wet Chemical |
Types of Fire Extinguishers and Their Uses
Different fire extinguishers contain different extinguishing agents, and each agent controls fire in a different way. For example, water mainly cools burning materials, while dry chemicals interrupt the chemical reaction of a flame.
However, choosing an extinguisher is not simply about its name or colour. Always check the fire class, extinguisher rating and instructions printed on the unit. Use a fire extinguisher only when the fire is small enough to tackle safely, and you have a clear escape route.
Water Fire Extinguisher
What is inside?
The main extinguishing substance is water (H₂O). Some water-based extinguishers may contain additives, depending on the product.
How Does a Water Fire Extinguisher Control Fire?
Water mainly controls fire through cooling. It absorbs heat from the burning material, which lowers its temperature. When enough heat is removed, the material may no longer be hot enough to continue burning.
Water extinguishers are generally used for suitable Class A fires, such as wood, paper, cardboard and cloth, subject to the extinguisher's rating.
Do: Use on Class A solid combustibles like wood, paper, cloth, and cardboard, as the high-pressure water cools the fuel below its ignition temperature to completely put out the fire.
Don't: Do not use live electrical equipment due to severe electrocution risk, and never use water on flammable liquids or grease fires because the water will violently spread the burning fuel.
Foam Fire Extinguisher
What is inside?
Foam extinguishers contain a water-based solution with foam-forming chemicals. The exact chemical formulation can vary between manufacturers and products.
How Does a Foam Fire Extinguisher Control Fire?
Foam controls a suitable fire by forming a layer over the fuel surface, separating the fuel from the air and helping to reduce the release of flammable vapours. The water contained in the foam also cools the burning material, helping to bring the fire under control.
Foam extinguishers can be suitable for certain Class A and Class B fires, depending on their tested rating.
Do: Use on Class A solid combustibles like wood and paper, and Class B flammable liquids like petrol, oils and paints, as the foam creates a blanket that smothers the flames and cools the fuel.
Don't: Do not use live electrical equipment unless the extinguisher is specifically rated and tested for such use, and never use on commercial kitchen deep-fat fryers.
ABC Dry Chemical Fire Extinguisher
What is inside?
ABC dry chemical extinguishers commonly contain monoammonium phosphate (MAP) as the active extinguishing chemical. The exact formulation varies by product.
How Does Monoammonium Phosphate Control Fire?
The fine powder enters the flame zone and helps interrupt the chemical chain reaction that keeps combustion going.
On suitable Class A materials, the powder can also form a coating over the burning surface. This helps reduce continued contact between the fuel and the fire.
ABC extinguishers can be rated for suitable Class A, B and C fires, depending on the specific extinguisher.
Important: ABC, BC and Class D powders are not interchangeable. Always check the extinguisher label and rating.
Do: Use on wood, paper, cloth, flammable liquids like gasoline, and live electrical equipment, as the multi-purpose powder smothers the flames across all three classes of fire.
Don't: Avoid using it in small or poorly ventilated indoor spaces, as the powder cloud can reduce visibility and affect breathing. Also avoid using it on commercial deep-fat fryers, where the force of discharge may spread or splash burning oil.
BC Dry Chemical Fire Extinguisher
What is inside?
BC dry chemical extinguishers usually contain sodium bicarbonate (NaHCO₃) or potassium bicarbonate (KHCO₃). However, the type of dry chemical used can vary depending on the extinguisher.
How Does BC Dry Chemical Control Fire?
The fine dry chemical is discharged into the flame and mainly works by interrupting the chemical chain reaction that sustains flaming combustion.
BC extinguishers are generally intended for suitable Class B and Class C fire risks, depending on their rating.
Do: Use on flammable liquids like gasoline, oil and paint, as well as live electrical equipment, where the extinguisher is appropriately rated. The dry chemical quickly interrupts the flame and helps prevent continued combustion.
Don't: Do not use on Class A solid combustibles such as wood, paper or cloth, as the powder lacks the cooling effect needed to stop these materials from deep-seated glowing and re-igniting.
CO₂ Fire Extinguisher
What is inside?
A CO₂ extinguisher contains carbon dioxide (CO₂) stored under pressure.
How Does a CO₂ Fire Extinguisher Control Fire?
When discharged, carbon dioxide expands rapidly around the flame. It reduces the oxygen concentration around the fire, making it harder for combustion to continue. The discharge also cools the fire.
CO₂ extinguishers are commonly used for suitable Class B fires and certain electrical fire risks, subject to the extinguisher's rating.
Do: Use on Class B flammable liquids and live electrical equipment such as computers, servers and fuse boxes because the gas leaves no messy residue and does not conduct electricity.
Don't: Do not use on Class A solid combustibles like wood or paper because the high-pressure gas can scatter burning embers and may fail to cool deep-seated fire.
Wet Chemical Fire Extinguisher
What is inside?
Wet chemical extinguishers commonly use potassium-acetate-based formulations, although the exact formulation varies by product.
How Does a Wet Chemical Fire Extinguisher Control Fire?
Wet chemical extinguishers are designed for fires involving cooking oils and fats.
The agent cools the hot cooking medium and reacts at the surface to form a protective layer. This helps separate the fuel from air and reduce the risk of re-ignition.
Do: Use on Class K/F fires involving cooking oils, fats and deep-fat fryers. Class K and Class F refer to the same general category of cooking-oil and fat fires, but the classification differs by fire-safety standard.
Important: Class K is used in the United States and Mexico, while Class F is used in Europe, the UK, India and other ISO-standard regions. The agent creates a cooling, soap-like layer that helps cut off oxygen and prevent re-ignition.
Don't: Do not use live electrical equipment unless specifically rated for it, and never use on Class D burning metals, as it can cause a dangerous reaction.
Clean Agent Fire Extinguisher
What is inside?
There is no single chemical called a “clean agent.” These extinguishers contain different gaseous or vaporising agents, depending on the product.
How Does a Clean Agent Fire Extinguisher Control Fire?
The exact extinguishing mechanism depends on the agent. Clean agents mainly absorb heat, while others interfere with the conditions required for combustion to continue.
They can be useful where powder or liquid residue could damage sensitive equipment, as long as the extinguisher is rated for the fire risk and application.
Do: Use on expensive electronics, server rooms and live electrical equipment where the product is specifically rated for the application, because clean agents leave little or no residue.
Don't: Do not use on deep-fat fryer grease fires or Class D burning metals, as the agent may not provide the cooling or specialist extinguishing action required.
Water Mist Fire Extinguisher
What is inside?
The main extinguishing substance is water (H₂O), discharged as extremely fine droplets.
How Does a Water Mist Fire Extinguisher Control Fire?
The very small water droplets provide a large surface area that absorbs heat efficiently. This produces a strong cooling effect that helps reduce the temperature of the burning material.
However, not all water mist extinguishers have the same fire ratings, so approved uses vary by product. Always check the extinguisher label and fire rating before use.
Do: Use on suitable Class A fires and, where specifically approved and rated, certain live electrical equipment. The fine water mist can provide effective cooling with reduced water discharge compared with a conventional water jet.
Don't: Do not use on Class B flammable liquids or Class K commercial cooking-oil fires unless the extinguisher is specifically designed and rated for those hazards. Incorrect use can spread the burning material.
Specialist Class D Fire Extinguishers
What is inside?
Class D extinguishers contain specialist dry powders selected for particular combustible-metal fire risks.
The exact powder depends on the metal involved. No single Class D agent suits every combustible metal.
How Does a Specialist Class D Powder Control Fire?
The specialist agent is selected to suit the particular burning metal. It helps control and isolate the burning material, reducing the conditions that allow combustion to continue.
Because different metals can react differently during a fire, selecting the correct powder is essential.
Do: Use on suitable combustible metals such as magnesium, titanium, sodium and potassium only where the extinguisher is specifically rated for the metal involved. Apply the powder correctly to smother the fire and prevent further access to oxygen.
Don't: Do not use water, foam, CO₂ or ABC dry chemical extinguishers on combustible-metal fires unless the equipment is specifically approved for that hazard. An unsuitable agent can cause a dangerous reaction.
Fire Extinguisher Types and Which Fire Extinguisher Should You Use?
The chart below gives you a quick guide to different fire extinguisher types and the fires they suit. Before using any extinguisher, always check its label, fire rating and manufacturer's instructions to make sure it is suitable for the fire.
Fire Extinguisher Types and Uses Chart
The table below shows the common fire risks each extinguisher is designed to tackle.
Always check the extinguisher's approved fire rating, label and manufacturer's instructions before use.
| Fire Extinguisher Type & Main Agent | How It Controls Fire | Suitable For | Fire Risks | Comments | |||||
|---|---|---|---|---|---|---|---|---|---|
| Class A Solids | Class B Liquids | Class C Gases | Class D Metals | Electrical Energised | Class K/F Cooking Oils/Fats | ||||
|
Water
Water
|
Cools the burning material and reduces its temperature. | Class A fires — wood, paper, cardboard, cloth and similar solids. | ✓ | × | × | × | × | × | Not suitable for flammable liquids, energised electrical equipment, combustible metals or cooking oils/fats. |
|
Foam
Foam-forming agent
|
Cools the fire and forms a blanket over suitable burning liquids to reduce vapour release. | Class A and certain Class B fires, depending on rating. | ✓ | ✓* | × | × | − | × | Do not use on cooking oil/fat or energised electrical fires unless specifically approved. |
|
Dry Powder
ABC
|
Interrupts the combustion process and suppresses the flame. | Class A, B and C fires; ABC powder. | ✓* | ✓* | ✓* | × | ✓* | × | May leave residue. Not suitable for cooking oil/fat or specialist metal fires unless designed for them. |
|
CO₂
Carbon dioxide
|
Reduces oxygen around the flame and provides a cooling effect. Leaves no residue. | Class B fires and electrical equipment where rated. | × | ✓* | × | × | ✓* | × | Not suitable for cooking oil/fat fires, combustible metals or other fires outside its rating. |
|
Wet Chemical
Wet chemical agent
|
Cools the hot cooking medium and forms a layer to prevent re-ignition. | Class K/F fires — cooking oils and fats. | ✓* | − | × | × | × | ✓* | Not for electrical fires or other fire types outside its rating. |
|
Clean Agent
Gaseous/vaporising agent
|
Suppresses combustion with minimal residue, protecting sensitive equipment. | Selected Class A/B and electrical risks, depending on agent and rating. | ✓* | ✓* | − | × | ✓* | − | Check the agent, application and fire rating before use. |
|
Water Mist
Fine water droplets
|
Fine droplets absorb heat and cool the fire efficiently. | Selected fire risks based on certification and rating. | − | − | − | − | − | − | Do not assume it is suitable for every fire class. |
|
Specialist Powder
e.g. Class D
|
Uses a specific formulation designed for particular fire risks such as combustible metals. | Class D fires — specific metals such as magnesium, aluminium, sodium and potassium. | × | × | × | ✓ | × | × | Not for general use. Select based on the metal and site hazard. |
* Suitability depends on the specific extinguisher's tested fire rating, certification, application and manufacturer's instructions.
Remember This chart is a quick reference guide. Always check the extinguisher label, fire rating and manufacturer's instructions before use.
The right extinguisher depends on the type of fire, the extinguisher's approved rating and the specific situation.
How to Use a Fire Extinguisher – PASS Method
The PASS method is commonly used to remember the basic operating sequence for many portable fire extinguishers.
Video Link:
Watch the PASS Method VideoP – Pull
Pull the safety pin or release the safety mechanism. This allows you to operate the extinguisher.
A – Aim
Aim the nozzle or hose at the base of the fire, where the burning material is located. Keep a safe distance from the fire.
S – Squeeze
Squeeze the handle slowly and firmly to release the extinguishing agent.
S – Sweep
Move the nozzle from side to side across the base of the fire until the fire is under control or the extinguisher is empty.
Remember: Only use a fire extinguisher on a small fire when it is safe to do so. Always keep a clear escape route behind you, and never put yourself at risk.
Fire Extinguisher Inspection and Maintenance
Fire extinguishers must remain accessible, serviceable and ready for use.
Regular inspection and maintenance should consider:
Whether the extinguisher is in its designated location
Whether access to the extinguisher is clear
Visible damage or corrosion
The condition of the safety pin and operating mechanism
Pressure indication where applicable, ensuring the gauge is within the recommended operating range. Learn how to check a fire extinguisher pressure gauge .
Signs that the extinguisher has been discharged or tampered with
Whether servicing is due
Damaged, discharged or improperly maintained extinguishers should not be relied upon during an emergency.
For workplaces, inspection and maintenance should follow applicable requirements, manufacturer instructions and relevant Indian fire-safety standards.
Fire Extinguisher Safety Tips
Follow these basic fire extinguisher safety practices:
Select extinguishers to suit the fire risks in your workplace.
Keep them visible and within easy reach.
Make sure nothing blocks access to firefighting equipment.
Make sure employees know where the extinguishers are located.
Inspect and maintain extinguishers regularly.
Provide suitable fire extinguisher training for relevant employees.
Check the extinguisher label before using it.
Maintain a clear escape route when tackling a small fire.
Never take unnecessary risks to protect property.
Evacuate immediately if the fire becomes unsafe to control.
Safety first: Only attempt to use a fire extinguisher when it is safe to do so and you have a clear escape route.
Fire Extinguisher Training
Understanding fire extinguisher types and uses is an important part of workplace fire safety. Employees should know the common fire risks in their work environment, where extinguishers are located, which extinguishers are provided and when it is safer to evacuate rather than attempt to fight a fire.
Green World Group provides fire extinguisher training to help employees understand fire risks, fire extinguisher selection, basic operating procedures and emergency response. Training should complement, rather than replace, appropriate fire-risk assessment, emergency procedures and properly maintained firefighting equipment.
Whether you want to improve your own fire safety knowledge or make your workplace safer through corporate fire safety training , fire safety audits or consultancy services , Green World Group can be your trusted safety partner in building a safer and better-prepared workplace.
Fire Safety Audit
To know how our consultant perform Fire Safety Audit:
View the Fire Safety Audit Guide →Important Fire Safety Note
This article provides general fire safety awareness and guidance. The selection, installation, inspection and maintenance of fire extinguishers should always follow applicable Indian Standards, manufacturer guidance, workplace fire risk assessments and local fire safety requirements.
