Under the design conditions, the fan whose wind pressure is 15kPa~ 0.2mpa or compression ratio E =1.15~3 is called a blower. It can be divided into axial flow fan, centrifugal fan and rotary fan according to the working principle. Fans are widely used in tunnels, underground garages, senior civil buildings, metallurgy, factories and mines and other places for ventilation and high-temperature fire smoke exhaust. It is mainly composed of impeller, casing, inlet collector, guide vane, motor and other components. Roughly the commonly used have the following types: (1) centrifugal compressor power plant general centrifugal fan fan (3) (4) [2] [5] general axial flow ventilator roots blower fan once [6] sewage treatment of high temperature air fan being fans' levies ⑽ mine fire fan fan fan fan fan [14] [13] Marine ⑿ food ⑾ dust exhausting fan ⒂ roof fan has displayed the boiler drum induced draft fan