Vertical cantilever pump

Claim 1

A vertical cantilever pump adapted for use in pumping liquids of a corrosive and/or abrasive nature, said pump comprising a vertically downwardly extending cylindrical support pedestal having a pump casing adjacent its lower end for positioning same within a bath of liquid confined by a tank, said pump casing having an opening in an upper wall thereof and a liquid inlet and a pumped liquid outlet, and a pump drive shaft freely extending downwardly through said pedestal and said pump casing opening for supporting an impeller within said pump casing, said pedestal being arranged in flow communication with said pump casing through said pump casing opening and said pedestal being of a substantially closed construction whereby pumped liquid escaping from said pump casing through said pump casing opening upwardly along said pump shaft and into said pedestal forms a tubular column of liquid tending to reach a normal height proportional to normal pumped liquid discharge pressure, said pedestal and said impeller and said casing being formed of a fiber glass synthetic resin thermoset composite resistant to said liquid, said pump shaft being formed with a lengthwise extending metal core element fixed to said impeller and a covering sleeve bonded to said core element for shielding same from contact with said liquid and cooperating therewith to define an extremely rigid pump shaft, said covering sleeve being formed of a wound fiber glass synthetic resin thermoset composit resistant to said liquid, said covering sleeve having its surface shaped to define a pump device cooperating with a relatively closely positioned bounding surface of said pedestal for creating a downwardly directed force acting on said pumped liquid escaping from said pump casing for maintaining said column at a height below an abnormal height permitting escape of liquid from said tank upon occurrence of a back pressure in excess of said normal pumped liquid discharge pressure, and said covering sleeve surface being tapered relative to said bounding surface of said pedestal in a direction downwardly towards said impeller and defining a spiralwise extending pumping groove.