Application of Vertical Pumps to Water Works Installations

Abstract

suction pumping units predominate in water works installations, vertical pumps have a good many advantages. Their application should be more general in the water works field. This paper deals principally with vertical-shaft, single-stage, end suction, motor-driven, volute pumps, as compared with horizontal double-suction pumps. Other types of vertical pumps are applicable under certain conditions. In low-head, high-capacity, wet-pit installations, for instance, propeller pumps, either axial or mixed flow, may be used. Deep well turbine pumps, designed and developed primarily for use in wells of restricted diameter, have sometimes been used for pumping stations, particularly in wet-pit installations where the discharge head is high. As these pumps have been developed for a special purpose, however, it seems logical that volute centrifugal pumps, of unrestricted diameter, would be preferable. The availability of well type pumps as an item of established production has apparently been an important consideration in their use at pumping stations. Saving in space and low elevation of the pump with respect to the motor have sometimes been attained by the use of double-suction pumps with the shaf placed vertically. Here again the availability of he double-suction designs h s been an important factor. In a double-suction pump, the suction portion of the casing is intricate and the path of the water is tortuous as it approa hes the impeller. In an end suction pu p with an overhung impeller, the discharge volute portion of the casing is about the same as for the double-suction pump, but the entrance to the impeller is much simpler and is direct. Not only are the intricacies of the suction portion of the casting eliminated, but the water entering is not obstructed by the shaft.