The flex absorber should be fastened to the end closest to the vibration source.

• A. False
• B. True
• C. Not specified
• D. Only to the source

Answer: (A)

Damping vibration in ductwork works best when the absorber sits between the vibrating portion and the rest of the system, acting as a buffer as the energy moves away from the source. If the flex absorber is attached right at the vibration source, the initial high-amplitude motion hits the absorber mounting directly and much of the energy can still propagate into the downstream duct and supports. By fastening the absorber at the end farthest from the vibration source, the absorber intercepts and dissipates more of the vibration before it travels further, reducing transmission to the rest of the system and to the building structure. So, this placement is not correct—it's best to install the absorber at the far end, away from the vibration source.