“One pump size and one characteristic curve only” … is this statement correct?

Abstract

Characteristic curves of centrifugal pumps are used to illustrate operating behaviour and are used as the basis for assessing hydraulic capability. To determine the head, measurement procedures are laid down in international codes such as ISO 3555. These codes also describe the set-up of measuring instruments so that characteristic curves are comparable. But what happens if pumps must be measured in a plant where setting up the measuring conditions according to ISO codes is impossible? How will the characteristic curves be influenced by measuring planes and measuring points which deviate from regulations? As a search in the available literature revealed no useful information on this theme, the only way to answer these questions was to investigate the influence of the arrangement of the measuring planes and measuring points on the characteristic curves, especially head and efficiency.