Submersible pump

Claim 1

IN A MULTI-STAGE, CENTRIFUGAL SUBMERSIBLE PUMP, A PUMP BODY COMPRISING A PLURALITY OF DIFFUSER UNITS, EACH DIFFUSER UNIT COMPRISING A BACK PLATE HAVING UPPER AND LOWER CENTRAL PLANAR PORTIONS, A DIFFUSER HAVING UPPER AND LOWER PLANAR SURFACE PORTIONS, AND AN IMPELLER DISPOSED BETWEEN SAID DIFFUSER AND BACK PLATE, LIQUID GUIDE VANES BEING PROVIDED ON THE UNDER SURFACE OF SAID BACK PLATES, MEANS FOR EFFECTING ROTATION OF SAID IMPELLER, EACH IMPELLER BEING OF THE ENCLOSED TYPE HAVING AN UPPER AND LOWER SHROUD, THE SAID UPPER SHROUD OF SAID IMPELLER BEING IN SPACEDLY PARALLEL, UNDERLYING RELATIONSHIP WITH RESPECT TO THE LOWER PLANAR PORTION OF THE RELATED DIFFUSER, THE LOWER SHROUD OF SAID IMPELLER BEING IN SPACEDLY PARALLEL, OVERLYING RELATIONSHIP WITH RESPECT TO THE UPPER CENTRAL PLANAR PORTION OF THE ASSOCIATED BACK PLATE, THE LIQUID GUIDE VANES UPON THE SAID BACK PLATE COOPERATING WITH THE UPPER PLANAR CENTRAL PORTION OF THE DIFFUSER OF THE ADJACENT DIFFUSER UNIT COOPERATING TO DEFINE LIQUID PASSAGEWAYS SAID LOWER SHROUD HAVING A CENTRALLY PROVIDED EYE, A PERIPHERAL SKIRT DEPENDING FROM THE EDGE OF SAID EYE, EACH BACK PLATE HAVING AN ENLARGED CENTRAL APERTURE, THE SKIRT OF THE RELATED IMPELLER EXTENDING DOWNWARDLY INTO THE APERTURE OF THE RELATED BACK PLATE, AND MEANS FOR EFFECTING STABLE INTERRELATIONSHIP BETWEEN SAID BACK PLATE AND SAID DIFFUSER.