Regenerative turbine pump having low horsepower requirements under variable flow continuous operation

A regenerative turbine pump apparatus which comprises:

• a housing having an inlet and an outlet;
• a generally circular impeller having a circumference and having a geometric axis, said impeller being mounted for rotation within said housing about said geometric axis, said impeller having first and second generally circular, generally planar faces, at least said first generally circular face having a first plurality of vanes extending from said circumference generally toward said geometric axis, each of said vanes having generally planar mutually parallel side walls disposed in oblique relationship to a tangent to said impeller proximate to the intersection of said vane and said circumference, adjacent vanes about said circumference in said first plurality of vanes each being separated by a slot extending from said circumference and extending to a substantially rectilinear line, said slots being machined into said impeller by a process which includes sequentially advancing a milling cutter, rotating on an axis which at all times is in a first plane parallel to said first face, to cut one side of a slot in said impeller and then withdrawing said milling cutter, indexing said impeller by rotating said impeller on the axis thereof and again advancing said milling cutter, rotating on an axis which at all times is in said first plane parallel to said first face, to cut another side of a slot in said impeller and then withdrawing said milling cutter.