Why would a class icon on a fire extinguisher display a slash through it?

• A. Using on that class would be ineffective.
• B. Using on that class would create additional risks.
• C. The use of that type has not been tested.
• D. It is illegal to use that type on that class.

Answer: (B)

A slash through a class icon on a fire extinguisher is a safety cue that this extinguisher isn’t suitable for that class of fire. It exists to prevent using the extinguisher in a way that could be dangerous or make the fire worse. Using an extinguisher on a fire it isn’t designed for can create additional risks, such as spreading flammable liquids or causing electrical shock on energized equipment, not just reduce effectiveness. That’s why the best answer is that using it on that class would create extra risks. It isn’t about testing or legality—the mark is about safe, appropriate use for the given fire type.