Design 7991 Radial Blade Industrial, SISW The 7991 Design is an industrial radial bladed fan wheel in a square fan housing. Common ApplicationsIndustrial supply and exhaust Size12-1/4" to 29-5/8" Wheel Diameter, SISWPerformance300 ACFM to 10,500 ACFM to 12" WG SPDocumentation Series 7900 Industrial Centrifugal FansDesign 7991 • LS WheelDocumentation | View