The working principle of a centrifugal fan is basically the same as that of a turbo compressor . Both are due to the low gas flow rate and little pressure change. Generally, there is no need to consider the change of gas specific volume, that is, the gas is treated as an incompressible fluid. Boilers and industrial furnaces ventilation and the air; an air conditioning equipment and household appliances provided apparatus in the cooling and ventilation; grain drying and sending the like. Centrifugal fans can be made into two types, right-handed and left-handed. Viewed from the side of the motor: the impeller rotates clockwise, which is called a right rotating fan; the impeller rotates counterclockwise, which is called a left rotating fan.