The 8800 STAR plenum fans are available in arrangements 3H and 3F. Wheel sizes range from 15" - 60" and are constructed of aluminum or steel (steel only on 60") with the single thickness airfoil blades. Features Airfoil Wheels Shock-free flow at the leading edge of the blades, plus streamlined flow over the blade surfaces, increases wheel efficiency and quietness. Steel Wheels Wheels have die-formed hollow airfoil blades continuously welded to back plate and rim to provide a rigid assembly for Class I and II applications. Aluminum Tabbed Wheels Tabbed wheels have die formed aluminum airfoil (hollow on 8800 Series) blades tabbed to backplate and rim for Class I applications. Tabbing eliminates welding distortion improving wheel balance and vibration free operation. Shafts Shafts are fabricated from medium carbon steel, (larger fans utilize forged shafts) and all are carefully turned, ground and polished to size. All shafts are correctly designed to give safe deflection and operate well below the first critical speeds. Options/Accessories Extended Lube Fittings Shaft Extensions Inlet Screens Unit Protective Enclosure Inlet Vane Controls Motor & V-Belt Drives Vertical Shaft Mounting Special Bearings Special Nameplates Narrow % Width Wheels Drive Guards Unitary Bases Special Coatings Split Pillow Block Bearing