Which extinguisher displaces oxygen to extinguish fires?

• A. Wet chemical extinguisher
• B. Clean agent extinguisher
• C. Class D extinguisher
• D. Class K extinguisher

Answer: (B)

The idea being tested is how some extinguishing agents work by reducing the oxygen available to the flame in a space. Clean agent extinguishers are designed for rapid release in enclosed areas, where the agent spreads quickly and interferes with the flame while absorbing heat. This combination helps suppress the fire and can effectively reduce the oxygen concentration around the flame, leading to quicker extinction without leaving a messy residue. This makes them a good fit for spaces with occupants or sensitive equipment.

Wet chemical extinguishers protect by saponifying fats and cooling, not by cutting off oxygen. Class D extinguishers are for metal fires and use dry powder to separate fuel from oxygen and heat. Class K extinguishers are for cooking oils and also rely on chemical reactions at the fuel surface, not oxygen displacement.