A smoke exhaust fan is a mechanical device that quickly exhausts odors, high temperatures, and cooking fumes generated during food processing in the kitchen. The main control parameters for selecting smoke exhaust fans are operating temperature, air volume, total pressure, efficiency, noise, motor power, speed, and shaft power. The smoke exhaust fan should be able to operate normally for a long time under the condition that the medium temperature is not higher than 85 ℃. The smoke exhaust fan should ensure that it can work continuously for 30 minutes when the temperature of the conveying medium is at 280 ℃, and can continue to operate normally when the medium temperature cools down to ambient temperature.