Which statement about Class D extinguishers is true?

Which statement about Class D extinguishers is true?

• A. They are used for ordinary combustibles
• B. They are used for fires involving combustible metals
• C. They are effective on energized electrical equipment
• D. They are never used for metal fires

Answer: (B)

Fires involving combustible metals require a special extinguishing approach. Class D extinguishers are designed with dry powders or other agents that smother the metal surface and absorb heat, forming a protective layer that slows or stops the metal’s intense reaction with oxygen. They’re specifically for metals like magnesium, titanium, aluminum alloys, sodium, and potassium, which behave very differently from ordinary fuels. This is why the statement is the best answer: it correctly identifies the purpose of Class D extinguishers. They aren’t meant for ordinary combustibles (paper, wood, textiles), which require water, foam, or regular dry chemical, and they aren’t used on energized electrical equipment (that situation calls for de-energizing first and using a different class such as C). Also, the idea that they’re never used for metal fires is incorrect—this class exists precisely for those metal fires. The bottom line is that metal fires need a specialized extinguisher media that can safely and effectively handle the metal’s unique properties.

Fires involving combustible metals require a special extinguishing approach. Class D extinguishers are designed with dry powders or other agents that smother the metal surface and absorb heat, forming a protective layer that slows or stops the metal’s intense reaction with oxygen. They’re specifically for metals like magnesium, titanium, aluminum alloys, sodium, and potassium, which behave very differently from ordinary fuels.

This is why the statement is the best answer: it correctly identifies the purpose of Class D extinguishers. They aren’t meant for ordinary combustibles (paper, wood, textiles), which require water, foam, or regular dry chemical, and they aren’t used on energized electrical equipment (that situation calls for de-energizing first and using a different class such as C). Also, the idea that they’re never used for metal fires is incorrect—this class exists precisely for those metal fires. The bottom line is that metal fires need a specialized extinguisher media that can safely and effectively handle the metal’s unique properties.