For what type of metals is a Class D fire extinguisher used?

A Class D fire extinguisher is specifically designed for use on fires involving combustible metals. These metals include magnesium, titanium, potassium, sodium, and others that can react violently with water and produce flammable hydrogen gas. Therefore, the correct answer highlights the importance of using the appropriate extinguisher to handle fires caused by these types of materials safely.

Combustible metals are unique because they require special firefighting agents that can effectively smother the fire without causing a hazardous reaction, which is why a Class D extinguisher often contains dry powder agents that are safe for such situations. Understanding the specific application of a Class D extinguisher is crucial for anyone working in environments where such metals are present.