Vortex pumps

Claim 1

A vortex pump of the type having a casing formed with a generally toroidal peripheral wall and a radial outer wall, an axial inlet for the casing in said radial outer wall, a cylindrical impeller recess formed in the casing opposite said inlet and joining the inner periphery of said volute, an outlet having one wall leading tangentially from said casing and an impeller with peripherally unshrouded vanes projecting axially from a generally radial flange and rotatable in said recess; the improvement wherein the peripheral casing wall is a volute, the entire internal wall of said volute having a smooth arcuate cross sectional shape with corresponding parts of the volute wall having substantially the same shape around the volute, said impeller recess intersecting said volute wall at an obtuse angle substantially around the volute, said intersection lying in a skew plane with the obtuse angle of intersection progressively increasing around the volute from the deepest portion of the volute at the tangential outlet wall to the shallowest, cutwater portion of the volute at the diametrically opposite outlet wall, said radial outer casing wall lying substantially in a plane that is equidistant from the impeller, said impeller having a substantial radial clearance with said recess, the radially inner ends of the impeller vanes being unshrouded to form a recessed eye.