A Practical Approach to Centrifugal Pump Design

This paper outlines a unique approach to the design of a common centrifugal pump. It is based on establishing a three-point performance curve-namely, the shutoff head (zero capacity), the design point, and the maximum capacity that represents the desired performance-and then designing the pump to meet these conditions. In order to eliminate the need of various coefficients, Stepanoff's (2)* dimensionless chart is used to select and establish a head-capacity value at the best efficiency point. Modified vector diagrams together with a sample problem showing the necessary equations, charts, and calculations illustrate the simplicity of design. The problem is based on a radial design impeller at 245 gpm at 75 ft of head and 3450 rpm. Other pump capacities may be similarly designed by varying the design parameters.