UNUSED Spencer Multistage Blower. Rated 1633 CFM, Diff. Pressure Oz: 134, Inlet pressure PSIA: 11.89, 100 deg F. Four-Bearing Outboard (4BOB) blower is a multistage centrifugal unit which handles air and other gases, working either as blower or exhauster. With 100 HP, 230/460V3500 RPM, TEFC Motor. Model 85100-HMOD, S/N: 279907.