This Standard applies to: a)Centrifugal Fans.b)Axial and Propeller Fans.c)Power Roof and Wall Ventilators.d)steam and Hot Water Unit Heaters.It is intended that this Standard shall also apply to Central Station Heating, Ventilating and Air Conditioning Units. When a detailed method of publishing sound ratings for these units has been adopted an addendum to this Standard will be issued.