This standard specifies the basic type, technical requirements, test methods, inspection rules, marking, packaging and storage of forward multi-wing centrifugal fans. This standard is suitable for conveying air or mixed gases that do not contain corrosive, flammable or explosive components. There should be no sticky or fibrous substances in the medium. The dust content and other solid impurities in the medium should be less than 100g/3, and the medium should contain no viscous or fibrous substances. Ventilators (including bare metal and units) containing solid particles with a diameter of no more than 1