1. Assume a customer requires a fan to operate at 33,120 CFM at 2.5" SP, at standard air density. Per the specifications, a BC backward inclined fan is required. 2.Based on the above information, from Twin City Fan's Catalog 300, a 490 BC SWSI, CL II fan is selected. This fan will operate at 620 RPM and 20.01 BHP to meet the required ...