Tennessee Wastewater Operator Practice Exam

What type of fire extinguisher is appropriate for combustible metal fires, such as those involving magnesium and titanium?

1. Class K

2. Class C

3. Class D

4. Class B

The correct answer is: Class D

The correct choice for extinguishing combustible metal fires, particularly those involving metals like magnesium and titanium, is the Class D fire extinguisher. Class D extinguishers are specifically designed to combat fires fueled by combustible metals. These types of fires burn at extremely high temperatures and can react violently with water and other common extinguishing agents. Class D extinguishers use dry powder agents that smother the fire and absorb heat, effectively controlling fires that involve metal elements without the risk of chemical reactions that water or foam might provoke. Understanding why the other options are less suitable provides more context. Class K extinguishers are aimed at kitchen fires involving cooking oils and fats, while Class C extinguishers are designed for electrical fires. Class B extinguishers are for flammable liquids, such as gasoline or oil. None of these agents are appropriate for extinguishing metal fires, which is why Class D is the only effective option in this scenario.