Which component most effectively reduces vibration transmission from a fan to connected ductwork?

• A. Duct collar
• B. Rubber seal
• C. Flex connector
• D. Screwed joints

Answer: (C)

Vibration transmission from a fan to connected ductwork is best reduced when there is a compliant, energy-dissipating path between the two. A flexible connector is designed to bend and absorb movement, converting some of the fan’s vibrational energy into flexing of the connector material, which dampens and isolates the vibration before it reaches the ductwork. Rigid connections like a duct collar or screwed joints create a stiff path that readily transmits vibration, so they don’t reduce the vibration as effectively. A rubber seal mainly blocks air leaks and isn’t intended to damp vibration significantly. Therefore, the flexible connector provides the greatest vibration isolation.