A pump of the centrifugal type that combines in a single hydraulic stage and with a single hydraulic impeller and casing the dual ability to pump, under vacuum, either liquids or gases. These pumps are advantageously used for sump, bilge, mine water gathering, tankcar unloading, vacuum evaporator applications, chemical processing, and other uses where the liquid is below the pump centerline, or under high vacuum. The suction lift is usually guaranteed at 20 ft (6.1 m) for cold water at sea level.