Centrifugal fan is mainly composed of impeller, casing, wheel hub,shaft, air inlet and air outlet, and bearing pedestal, supporting, and belt pulley (or coupling), and other components. Fan Impeller Rotation Its axis is connected to the motor shaft through the coupling or pulley and belts.When motor drives the impeller to rotate, the air also along with the impeller rotating,under the action of inertial, the air is thrown around, and pooled into the spiral casing. In the process of air flow to the air outlet in casing,the cross section expands, wind speed slows down, most dynamic pressure changes into static pressure, finally, the air is exhausted from air outlet in certain pressure. When the air is expelled by the impeller, there are some certain vacuum in impeller center, under the action of atmospheric pressure, the air outside of air inlet are induced into impeller. The impeller rotates constantly, so the air is induced and exhausted continually. Obviously, the blower fan pass the energy to air by impeller rotation so as to achieve the aim of the air ventilation. all xianrun blower The air intake (air inlet) of centrifugal fan pressure is a negative pressure, and exhaust port (air outlet) pressure is positive pressure. So it can force air to boilers, or kilns, they can also exhaust air from the furnace.