Minnesota Protective Agent Practice Test

How do you put out a Class B fire?

1. Water

2. Dry chemical and halon extinguishing agents

3. Foam

4. B and C

The correct answer is: B and C

Class B fires are those that involve flammable liquids, such as gasoline, oil, or grease. They can't be extinguished with water because water can cause the fire to spread; it tends to float these types of substances, spreading them over a larger area. Instead, extinguishing methods for Class B fires include dry chemical and halon extinguishing agents, as well as foam. Dry chemical extinguishers can interrupt the chemical reaction of a fire to suppress it, while halon extinguishing agents work by displacing the oxygen the fire needs to burn. Foam extinguishers, on the other hand, work by cooling the fire and coating the fuel, preventing its contact with oxygen. Therefore, both options B and C — dry chemical and halon extinguishing agents and foam — are suitable for putting out a Class B fire.