The Packaged Backward Inclined (PBI) fan’s wheel uses flat backward inclined steel blades designed for long life in hostile environments, such as fumes, dirty air and light granular materials. Coupled with the streamlined inlet, the fan is said to dramatically reduce vibration and noise levels. Fully run tested, the energy efficient PBI is backed by a three-year warranty. The fan, designated Design 64, is designed to increase the stable operating range by more than 20%, thereby cuttting down on the number of necessary fan sizes. It is available in 12 sizes , varying widths, and three motor rpm.