What classes of fire cannot be extinguished using a foam type fire extinguisher?

• A. Class A and D fires
• B. Class B and C fires
• C. Class A and B fires
• D. Class C and D fires

Answer: (B)

The question pertains to the effectiveness of foam type fire extinguishers on different classes of fire. Foam fire extinguishers are primarily designed for Class A (ordinary combustibles like wood or paper) and Class B (flammable liquids like gasoline or oil) fires.

Class C fires involve energized electrical equipment, and using a foam extinguisher could be dangerous because foam conducts electricity. Therefore, it is not suitable for use on Class C fires. Class D fires involve combustible metals such as magnesium or sodium, and again, foam is not effective for extinguishing these fires, as it can react with these metals and even exacerbate the fire.

The correct answer indicates that foam extinguishers cannot effectively extinguish Class B and Class C fires. While foam is used for Class B, it is incorrect to use it for Class C due to the risks involved. Understanding the classification helps ensure appropriate measures are taken to mitigate fire hazards safely and effectively.