Alberta Boilers Safety Association (ABSA) Practice Test

Which material is classified as a Class D fire?

1. Cloth and paper

2. Lubricating oil

3. Electrical wire

4. Magnesium

The correct answer is: Magnesium

Class D fires involve combustible metals that require specific types of extinguishing agents for effective suppression. Typical materials classified under Class D include magnesium, aluminum, and sodium. These metals ignite at high temperatures and may burn rapidly, causing severe hazards. Water or standard fire extinguishers are ineffective against Class D fires, as they can react violently with water, exacerbating the fire. In contrast, the other materials listed fall under different fire classifications. For instance, cloth and paper are categorized under Class A fires, which involve ordinary combustibles. Lubricating oil is classified as Class B, representing flammable liquids, while electrical wire pertains to Class C fires, which involve energized electrical equipment. Thus, magnesium is the only material in this question that fits the criteria for a Class D fire, highlighting its distinct handling and extinguishing requirements.