For fires involving combustible metals, which extinguisher type is specified?

• A. Water
• B. Class D extinguishers
• C. Class A extinguishers
• D. Class K extinguishers

Answer: (B)

Fires involving combustible metals require an extinguishing method that cools and isolates the metal without reacting with it. Water is unsafe because many reactive metals (like magnesium or sodium) react vigorously with water, releasing heat and hydrogen gas that can cause explosions or spread the fire. The best choice is an extinguisher designed for metal fires, which uses a dry powder that blankets the molten metal, absorbs heat, and forms a crust that separates the metal from oxygen and fuel, helping to smother the flame and prevent reignition.

The other options don’t fit because water-fire interactions can be dangerous with metals, extinguishers for ordinary combustibles aren’t engineered for metal chemistry, and those intended for cooking oils are for fats and oils, not metal fires.