An isolation damper capable of forming an airtight or zero-leakage seal. The damper includes an annular frame or frame and a flexible seal member that extends around an inner surface of the frame. The seal member is at least partially embedded or integrated into the frame and includes an exposed surface. The seal member can be a single or multi-component seal member. A rotatable shaft extends across the interior annular aperture of the annular frame, and a blade is coupled to the shaft. The blade that is attached to the shaft is rotatable between closed and open positions. An outer circumferential edge of the blade engages the exposed surface of the seal member when the blade is rotated to a closed position thereby forming an air tight seal.