VENCO MFDV Series Fan Type Air Dampers without Motor are used together with the standard axial fans and smoke exhaust fans. The blades are normally in closed position due to weight of the blades. They are opened with the air flow when the fan starts to run. Air dampers must be installed at the outlet of the axial fan. Air damper blades are designed to create minimum pressure drop when it is open and allows minimum air leakage when it is closed. Air damper casing and the blades are galvanized steel.