Fire extinguishers play a very important role in combating fires, but selecting the right class is most important for safety and effectiveness. This article provides you an overview of the five main types of fire extinguishers, their applications, and how to choose the right one based on the class of fire.
Fire Classes Explained
Fires are classified based on the type of fuel burned. To know these classes are very important to selecting the right class of fire extinguisher:
- Class A: Combustible solids like paper, wood, and textiles.
- Class B: Flammable liquids such as petrol, diesel, and oil.
- Class C: Flammable gases like propane and methane.
- Class D: Combustible metals, including magnesium and aluminum.
- Electrical Fires: Fires involving electrical equipment.
- Class F: Fires caused by fats and cooking oils.
1. Water Extinguishers (Red Label)
- Best For: Class A fires (paper, wood, textiles).
- Mechanism: Sprays water to cool and extinguish flames.
- Pros: Affordable, eco-friendly, and easy to maintain.
- Limitations: Unsafe for Class B, Class C, electrical fires, or cooking oils.
- Common Uses: Offices, schools, and residential areas.
The water fire extinguisher is the best for Class A fires because it puts out the flames by spraying water under high pressure. Water fire extinguishers are also safe to use around food, children, and vulnerable adults because they do not contain any dangerous chemicals.
Electronic fires, cooking fires, fires using flammable liquids, and fires caused by flammable gasses should not be put out with water fire extinguishers.
2. Foam Extinguishers (Cream Label)
- Best For: Class A and Class B fires (solids and flammable liquids).
- Mechanism: Forms a foam layer to smother flames.
- Pros: Can be used on some electrical fires if discharged from a safe distance.
- Limitations: Leaves residue and is unsuitable for Class F fires.
- Common Uses: Warehouses, retail spaces, and workshops.
Foam fire extinguishers are used on burning fluids like gasoline, paint, or turpentine because the foam suppresses the fire in solids and liquids (Class A and B), but not in burning fats or cooking oils (Class F). Certain electrical fires can also be put out with a foam extinguisher if they have been tested and released from a distance of one meter. They are more costly than water extinguishers, and they leave a residue that requires to be cleaned up.
3. Dry Powder Extinguishers (Blue Label)
- Best For: Class A, B, and C fires; specialist powders for Class D (metals).
- Mechanism: Smothers the fire with a crust of powder.
- Pros: Versatile and effective on a range of fires.
- Limitations: Hazardous if inhaled, has no cooling effect, and can cause cleanup challenges.
- Common Uses: Industrial sites, vehicles, and construction areas.
Powder fire extinguishers are used to put out Class A, B, and C fires, which are fires that are burning solids, liquids, or gasses. Specialized powder extinguishers are produced to extinguish type D fires that contain flammable metals like aluminum, magnesium, or lithium.
They work by making a crust out of the powder that smothers the fire and stops it from spreading. The powder’s difficulty in sufficiently cooling the fire and its failure to sink into materials are drawbacks that might allow the fire to restart.
They should be utilized in well-ventilated places and are not suitable for use in offices or homes because the powder is harmful if inhaled. The powder requires a lot of cleanup after use and ruins delicate items like machinery and furniture. They are useless on chip pan fires (Class F).
They are available in 1, 2, 4, 6, and 9 kg and are typically powerful and affordable.
4. Carbon Dioxide (CO2) Extinguishers (Black Label)
- Best For: Electrical fires and Class B fires.
- Mechanism: Displaces oxygen to suffocate flames.
- Pros: No residue and safe for electrical equipment.
- Limitations: Risk of re-ignition; not suitable for confined spaces.
- Common Uses: Offices, server rooms, and factories.
5. Wet Chemical Extinguishers (Yellow Label)
- Best For: Class F fires (cooking oils and fats).
- Mechanism: Cools flames and forms a barrier to prevent re-ignition.
- Pros: Effective for kitchen fires and also usable on Class A fires.
- Limitations: Limited use beyond Class F fires.
- Common Uses: Commercial kitchens and catering establishments.
Special Considerations
- Water Mist Extinguishers: These innovative devices work on most fire classes (A, B, C, and F) and are suitable for electrical fires up to 1,000 volts.
- Lithium-Ion Battery Fires: Require specialized extinguishers with Aqueous Vermiculite Dispersion (AVD) for effective suppression and cooling.
Conclusion
Selecting the right fire extinguisher is crucial for effective fire management. Always assess the materials and risks in your environment before choosing a fire extinguisher. Ensure your extinguisher is regularly maintained and complies with safety standards to be prepared when it matters most.