A centrifugal pump curve comprises a grid depicting head and flow rate and a series of lines that illustrate pump performance characteristics. Figure 1. is a typical pump curve, and each set of lines will be reviewed individually.
Many factors affect performance of a centrifugal pump and must be considered during pump selection. This chapter describes conditions that affect the centrifugal pump and is followed by details that will assist in eliminating negative conditions that cause pump failure.
The function of the centrifugal pump casing is to:
- Direct fluid into the eye of the impeller through the suction inlet.
- Minimize fluid recirculation from impeller discharge to impeller suction.
- Capture fluid discharge from the impeller in the case volute to most efficiently utilize work performed by the impeller and direct fluid away from the impeller. (See Picture 1. and 2.)
Centrifugal pumps are often referred to as kinetic energy machines. Rotation of the impeller causes fluid within the impeller to rotate at a high velocity, imparting kinetic energy to the fluid.