Patent ID: 8425205

Claim:
A centrifugal pump comprising: a pump unit comprising: a volute which comprises an inlet, an outlet and a chamber in communication with the inlet and outlet; and an impeller disposed in the chamber of the volute; and a drive unit comprising a stator and a rotor including a shaft, the shaft of the drive unit extending into the chamber of the volute, the impeller being attached to and driven by the shaft; wherein the inlet is coaxial with the chamber; and a baffle disposed in the inlet, the baffle comprising a guide plate angled to the axis of the inlet, the guide plate comprising a contact edge contacting an inner surface of the inlet and a free edge spaced from the inner surface of the inlet, a passage through the inlet being formed between the free edge and the inner surface of the inlet; wherein an air passage is formed in the inlet for allowing air in the chamber to bleed out during operation of the pump, the air passage being formed between an outer surface of the baffle and an inner surface of the inlet and being in continuous communication with the chamber.