: Centrifugal fan is to rely on the input mechanical energy, gas pressure side by side to send the gas machinery, it is a follower of Fluid Mechanics. Centrifugal fans are widely used in factories, mines, tunnels, cooling towers, vehicles, ships and buildings, ventilation, dust and cooling; boilers and industrial furnaces, ventilation and induced draft fan; cooling and air-conditioning equipment and household appliances ventilation; grain drying and should select; inflatable wind tunnel wind source and the hovercraft and propulsion. 
 : Centrifugal fans can be made of two types of D-and L from the motor side of the face, the impeller rotates clockwise called right rotary fan, the impeller counterclockwise rotation, called the left-rotating fan. 
 : Centrifugal fan according to the kinetic energy is converted to potential energy principle, the use of high-speed rotation of the impeller to accelerate the gas, and then slow down, change the flow of kinetic energy converted into potential energy (pressure). Single-stage centrifugal blower, gas from the axial into the impeller, change into a radial gas flows through the impeller, and then enter the diffuser. In the diffuser, the gas changes the flow direction resulting in deceleration, this deceleration of the kinetic energy into pressure energy. The pressure increase occurred mainly in the impeller, the second occurred in the diffuser. Reflux allows airflow into the next multi-stage centrifugal blower impeller, resulting in higher pressure.