Plenum Fan Wheel Type Backward-Curved Drive Type Belt Drive Includes Drive Package Yes Assembly Unassembled Wheel Diameter 22 in Airflow @ 0.250 in SP 4 139 cfm Airflow @ 0.500 in SP 3 742 cfm Airflow @ 0.750 in SP 3 226 cfm Airflow @ 1.000 in SP 2 527 cfm Maximum Inlet Air Temperature 104 Degrees F Shaft Diameter 1 1/8 in Bearing Type Ball Sound Level 8.5 sones @ 0.250 in SP and 5 ft Frame Material Galvanized Wheel Material Aluminum Inlet Diameter 13 1/2 in