Patent ID: 7896617

Claim:
A centrifugal pump impeller system for pumping fluid, including molten metal, comprising: an impeller adapted for rotating about an axis in a certain pumping direction of rotation, comprising: a circular and generally flat base; and a plurality of vanes mounted to the base, the vanes extending radially from a radially inward portion of the base to an outer-most edge of the base, each vane having a concave leading wall and a convex trailing wall, the trailing wall of each vane cooperating with the leading wall of an adjacent vane to define a curved passage, wherein the trailing wall of each vane is complementary in shape to the adjacent leading wall, such that the passage has a gradually increasing cross-sectional area from a radially inward inlet to a radially outward outlet; wherein said impeller is rotatable about a central axis such that fluid flowing through each passage follows the curved leading wall into the same general direction as the pumping direction of rotation.