Fans shall be single width, single inlet or double width, double inlet type with non-overloading fan impellers as specified in the Equipment Schedule. Type of fan blade also shall be forward curve or back ward inclined air foil. Fan blades using for kitchen hood shall be back ward inclined as specified in the Equipment Schedule.
The fan casings shall be of a true volute form and shall have inlet cores aerodynamically shaped to give an even distribution of air over the full width of the impeller.