Which type of air filter uses thick foam and honeycomb networks to trap dust particles?

• A. Paper
• B. Oiled Gauze
• C. Oil Foam
• D. Oil Bath

Answer: (C)

Filtration effectiveness comes from how the filter material is structured to create a tough, layered path for the air through it. Thick foam with a honeycomb network provides depth filtration: the dense foam offers a large, interconnected surface that air must pass through, while the honeycomb acts as a rigid skeleton that keeps the foam open and creates consistent air channels. When the foam is saturated with oil, dust particles are more likely to stick to the surface as they pass through, increasing capture and reducing re-entrainment. This combination—oil-impregnated, thick foam with a honeycomb structure—is what defines an oil foam air filter. Other options rely on different materials and structures (paper, oiled gauze, or an oil bath) that don’t combine thick foam, honeycomb support, and oil impregnation in the same way.