The fan closing device is also called the discharge device. Usually, the structure of the fan closing device is composed of rotor impeller with several blades, shell, seals, reducer, motor and so on.

When the upper bin material falls by its own weight to fill the gap between the blades, with the rotation of the blades in the lower discharge, therefore, the fan can be quantitative and continuous discharge.

Fan used in pneumatic system, the output of a pressure output system or negative pressure output system, shut the fan can be homogeneous, continuously to the transporting pipe feeding, to ensure that the pneumatic output tube of gas and solid is stable, so that the normal work of the pneumatic conveying, at the same time, and will close the fan on, and the lower air pressure and gas lock effect. Therefore, shut - off fan is an important component in pneumatic conveying system.

The closed fan can be used in the material collection system as an unloader for the bin. The fan is currently the top discharging device in China, commonly used in the dust removal system as one of the important equipment in the dust removal system, it is especially suitable for dust, small particle materials, by environmental protection, gold, chemical, food, cement, road construction, drying equipment and other industrial engineering projects.