Elmo Rietschle direct drive, air-cooled, oil-free, vertical flow rotary lobe vacuum booster flanged to a 3 HP, 575 volt, 60 Hz, 3-phase TEFC motor. Standard features include 3" hose barb connections, an integral bypass valve, inlet mesh filter screen, labyrinth seals, and a base frame with rubber isolation feet. Booster blowers are used in combination with backing pumps to significantly increase vacuum performance efficiently and cost effectively.