Anti-backdraft shutter assembly for an axial flow fan

摘要

An anti-draft shutter assembly for an axial flow fan fitted to a duct. The assembly consists of at least one counterbalanced flap 25 supported downstream of airflow from the fan when in operation, and at least one of the flaps beign pivotally supported outside the perimeter of the duct. The flap is biased by a counterbalance weight toward a duct closing position to close the duct when the fan is not operating. In the preferred embodiment, at least one flap is held in the closed position by a magnetic catch on the flap.