The common medium pressure fan is centrifugal fan, the impeller is covered with a mechanical shell, and the center of the impeller is the air inlet. When the medium pressure fan is working, the power equipment runs to drive the impeller to rotate and suck air from the air inlet. In the process of centrifugal fan blade rotation, the dynamic action is applied to the gas to improve the pressure and speed of gas, and the gas is discharged from the exhaust port along the blade channel under the action of centrifugal force.
In the working process of the medium pressure fan, although the rotation of the impeller improves the pressure and speed of the gas, the various changes of the gas are small. Therefore, in the design and use of the centrifugal fan, the gas is usually treated as an incompressible fluid. The gas treatment process of medium pressure fan is completed in the same radial plane, so the medium pressure fan is also called runoff centrifugal fan.