High pressure centrifugal fan is according to the kinetic energy into potential energy principle，using the high-speed rotation of the impeller gasacceleration，deceleration, and change the flow, the kinetic energy into pressure.

In a single-stage centrifugal fan, gas from the axial direction into the impeller, air flows through the impeller is changed into radial, then enters the diffuser.

In the diffuser, the flow direction of gas changes caused by deceleration，the speed converting kinetic energy into pressure energy.

Increased pressure occurred mainly in the impeller, followed in the diffusion process.

In the multi-stage centrifugal fan, with the return air into the next impeller, higher pressure.