Abstract: A centrifugal pump for accommodating entrained gas and vapor at low absolute suction pressures includes an impeller with a central inlet chamber. The impeller has a peripheral wall which is concentric with the impeller's axis; and, at least one passage extends outwardly from an inlet port in the peripheral wall to an exit port radially spaced from the chamber. Preferably, the pump includes a stationary inlet port device located within the central inlet chamber for separating the spinning impeller from incoming fluid.

Abstract: Method and apparatus for separating volatile contaminants from a liquid to be continuously distilled. A continuous still comprises evaporator (1) having a heating coil (2), and condensor coil (6), and distillate collector (5). An entrainment device (11) removes distillate (13) from collector (5) via line (10) and reduces pressure in evaporator (1). Feed liquid (21) containing volatile contaminants is charged batchwise to a pre-chamber (20) at sub-atmospheric pressure which is then sealed (valve 22) from feed supply (21). Volatile contaminants are extracted from the charge in prechamber (20) via line (26) and entrainment device (32). Pre-chamber (20) is subsequently placed in communication (via valve 25) with evaporator (1) whereby to equilibrate pressure between evaporator (1) and pre-chamber (20).