Volute Design For Lower Manufacturing Cost and Radial Load Reduction

Abstract

A volute for a pump featuring a volute or casing having a pump inlet for receiving a fluid being pumped, a pump discharge for providing the fluid, and a volute or casing vane forming double volutes therein. The volute has an upper cutwater farthest from the pump discharge defining an upper cutwater throat area and an end of passage for the upper cutwater, and also has a lower cutwater closest to the pump discharge defining a lower cutwater throat and a corresponding end of passage for the lower cutwater. The upper cutwater throat area is dimensioned to be greater than and not equal to the lower cutwater throat area so the upper cutwater throat area and the lower cutwater throat area provide substantially equal flow velocity at both the upper cutwater and the lower cutwater in response to an angular sweep of the fluid being pumped. The end of passage for the upper cutwater is dimensioned with an upper cutwater passage area that is greater than and not equal to a corresponding lower cutwater passage area of the corresponding end of passage for the lower cutwater so that upper and lower cutwater passage areas at the pump discharge are balanced as a function of differing rates of flow of the fluid being pumped therein and so that the fluid being pumped from associated ends of the upper and lower cutwater passage areas meets at the pump discharge with a substantially equal velocity.

What I claim is: 
     
         1 . A volute for a pump comprising:
 a volute wall;   a pump inlet for receiving a fluid being pumped;   a pump discharge for providing the fluid being pumped; and   a casing vane configured on the volute wall forming double volutes in the volute and being configured with an upper cutwater farthest from the pump discharge defining an upper cutwater throat area and an end of passage for the upper cutwater, and also configured with a lower cutwater closest to the pump discharge defining a lower cutwater throat and a corresponding end of passage for the lower cutwater;   the upper cutwater throat area being dimensioned to be greater than and not equal to the lower cutwater throat area so that the upper cutwater throat area and the lower cutwater throat area provide substantially equal flow velocity at both the upper cutwater and the lower cutwater in response to an angular sweep of the fluid being pumped; and   the end of passage for the upper cutwater being dimensioned with an upper cutwater passage area that is greater than and not equal to a corresponding lower cutwater passage area of the corresponding end of passage for the lower cutwater so that upper and lower cutwater passage areas at the pump discharge are balanced as a function of differing rates of flow of the fluid being pumped therein and so that the fluid being pumped from associated ends of the upper and lower cutwater passage areas meets at the pump discharge with a substantially equal velocity.   
     
     
         2 . A volute according to  claim 1 , wherein the upper cutwater and the lower cutwater are radially displaced at an angle α that is substantially less than 180°. 
     
     
         3 . A volute according to  claim 1 , wherein the upper cutwater and the lower cutwater are radially displaced at an angle α that is in a range of between 100° and 120°. 
     
     
         4 . A volute according to  claim 1 , wherein the upper cutwater and the lower cutwater are radially displaced at an angle α that is in a range of between about 108° and about 110°. 
     
     
         5 . A volute according to  claim 1 , wherein the volute forms part of a double volute pump having an impeller with impeller vanes and being arranged in one of the double volutes in the volute or casing.