Axial Downblast Roof Exhaust Fans Assembly Unassembled Mounting Location Roof Blade Diameter 20 in Base Diameter Not Applicable Base Length 30 in Base Shape Square Base Width 30 in Maximum Airflow 3 957 cfm Minimum Airflow 960 cfm Maximum Motor Horsepower 3/4 hp Minimum Motor Horsepower 1/4 hp Minimum Motor Speed 795 RPM Maximum Motor Speed 1 147 RPM Maximum Static Pressure 3/4 in wc Drive Type Not Applicable For High-Static Pressure Applications No For Air Type Clean Air