Page 15 - Centrifugal Pumps 2E

1

Introduction

System Analysis for Pump Selection

Before a pump can be selected or a prototype designed, the application
must be clearly defined. Whether a simple recirculation line or a complex
pipeline is needed, the common requirement of all applications is to
move liquid from one point to another. As pump requirements must
match system characteristics, analysis of the overall system is necessary
to establish pump conditions. This is the responsibility of the user and
includes review of system configuration, changes in elevation, pressure
supply to the pump, and pressure required at the terminal. Relevant in-
formation from this analysis is passed on to the pump manufacturer in the
form of a pump data sheet and specification. From the information given,
the following will ultimately determine pump selection.

• Capacity range of liquid to be moved
• Differential head required
• NPSHA
• Shape of head capacity curve
• Pump speed
• Liquid characteristics
• Construction

Differential Head Required

The head to be generated by the pump is determined from the system
head curve. This is a graphical plot of the total static head and friction

3