The centrifugal fan is a driven fluid machinery that relies on input mechanical energy to increase the gas pressure and discharge the gas. It can be made into right handed rotation and left handed rotation. Turn the impeller clockwise from the motor side, known as the right handed rotation fan. Rotate counterclockwise, known as the left handed rotation fan. The working principle is basically the same as that of the turbine compressor. Just because the gas flow rate is low, the pressure change is not large, generally do not need to consider the change of gas specific volume, namely the gas can be treated as the incompressible fluid. The newly installed centrifugal fan air volume will be too large. When the fan starts to run after the new installation, or when the use process is too large or too small, one of the following methods can be used to eliminate: Change the speed of the fan to adjust the flow rate. Adjust the flow rate by adjusting the opening and closing degree of the door. Change the resistance coefficient of the pipe network to regulate the flow rate. Change the higher or lower pressure fan to regulate the flow rate.