it seems that you can refer to JB/T 8691-2114 Noise Limits of Ventilators. But this seems a little incomplete. Usually refers to industrial use, and basically do not take any measures. Most of the fans used for catering are equipped with static speakers, which is relatively better. However, after the actual installation, the situation should meet the "GB12348-2118 Environmental Noise Emission Standard at the Boundary of Industrial Enterprises".