Objectives: At the end of this lesson you shall be able to
• To Determine the correct type of fire extinguisher to be used based on the class of fire

To determine the correct type of fire extinguisher based on the class of fire, you need to understand the classification system for fires and match it with the appropriate extinguishing agent.

Here’s an explanation of different types of fire extinguishers:

1. The best extinguishing agents for Class A fires (Involve ordinary combustible materials such as wood, paper, cloth, rubber, and some plastics) are water-based extinguishers, typically labeled as Class A extinguishers. They work by cooling the fuel below its ignition temperature and soaking the material to prevent re-ignition.

Water Extinguishers are effective against Class A fires, which involve ordinary combustible materials like wood, paper, cloth, and plastics. They work by cooling the fuel below its ignition temperature and soaking the material to prevent re-ignition. Water extinguishers are typically identified by a label with a letter “A” on it.

There are two methods of operation. (1) Gas cartridge type (2) Stored pressure type.  With both method of operation the discharge can be intruptted as required, conserving the contents and preventing unnecessary damage.

2. The most effective extinguishing agents for Class B fires ( Involve flammable liquids or gases such as gasoline, oil, grease, solvents, and paints) are foam, carbon dioxide (CO2), or dry chemical extinguishers. These agents work by smothering the fire and cutting off the oxygen supply, or by interrupting the chemical reaction of the fire.

Foam Extinguishers Foam extinguishers are suitable for Class A and Class B fires, which involve flammable liquids or gases. Foam forms a barrier over the fuel, preventing the release of flammable vapors and extinguishing the fire. These extinguishers are labeled with letters “A” and “B.” Foam extinguishers may be of stored pressure or gas cartridge types. Always check the operating instructions on the extinguisher before use.

3. Water-based extinguishers should not be used on Class C fires ( Involve energized electrical equipment such as appliances, wiring, circuit breakers, and outlets) because water conducts electricity and can cause electric shock or spread the fire. Instead, non-conductive agents such as carbon dioxide (CO2) or dry chemical extinguishers should be used. These agents extinguish the fire by smothering it without conducting electricity.

Carbon Dioxide (CO2) Extinguishers extinguishers are effective against Class B and Class C fires, which involve flammable liquids/gases and energized electrical equipment, respectively. CO2 works by displacing oxygen and smothering the fire. It’s non-conductive, making it safe for use on electrical fires. CO2 extinguishers are marked with letters “B” and “C.”

4. For Class D Fires ( Involve combustible metals such as magnesium, titanium, potassium, and sodium), specialized extinguishing agents, such as dry powder extinguishers specifically designed for metal fires, should be used. Water, foam, and other standard extinguishing agents can react violently with some metal fires, making them worse.

Dry Chemical Extinguishers are versatile and can be used on Class A, Class B, and Class C fires. They work by interrupting the chemical reaction of the fire and smothering it. Different types of dry chemical extinguishers are available, such as ABC extinguishers, which contain monoammonium phosphate, suitable for multiple fire classes.

5. For Class K Fires ( involve cooking oils, fats, and greases, typically found in commercial kitchens) Wet chemical extinguishers are specifically designed and work by cooling the oil and creating a barrier between the fuel and the oxygen to prevent re-ignition.

Wet Chemical Extinguishers are designed specifically for Class K fires, which involve cooking oils, fats, and greases. They work by cooling the oil and creating a barrier between the fuel and the oxygen to prevent re-ignition. These extinguishers are labeled with the letter “K” and are commonly found in commercial kitchens.

6. Class D Extinguishers: Class D extinguishers are designed for fires involving combustible metals like magnesium, titanium, potassium, and sodium. These extinguishers contain specialized dry powder agents specifically formulated for metal fires. They are labeled with the letter “D” and are typically found in industrial settings where metalworking processes occur.

When selecting a fire extinguisher, ensure it is appropriate for the specific class of fire you may encounter. Extinguishers are usually labeled with symbols and letters indicating the classes of fires they are suitable for. Regular inspection, maintenance, and training on the proper use of fire extinguishers are essential for effective fire safety.