Brochure

9898

6. Pump tests

This chapter describes the types of tests Grundfos continuosly performs on

pumps and their hydraulic components. The tests are made on prototypes in

development projects and for maintenance and ﬁnal inspection of produced

pumps.

6.1 Test types

For characterisation of a pump or one of its hydraulic parts, ﬂow, head, pow-

er consumption, NPSH and force impact are measured. When testing a com-

plete pump, i.e. motor and hydraulic parts together, the motor characteristic

must be available to be able to compute the performance of the hydraulic

part of the pump. For comparison of tests, it is important that the tests are

done identically. Even small dierences in mounting of the pump in the test

bench can result in signiﬁcant dierences in the measured values and there

is a risk of drawing wrong conclusions from the test comparison.

Flow, head, power consumption, NPSH and forces are all integral perform-

ance parameters. For validation of computer models and failure ﬁnding,

detailed ﬂow ﬁeld measurements are needed. Here the velocities and pres-

sures are measured in a number of discrete points inside the pump using

e.g. LDA (Laser Doppler Anemometry) and PIV (Particle Image Velocimetry)

for velocity, see ﬁgure 6.1 and for pressure, pitot tubes and pressures trans-

ducers that can measure fast ﬂuctuations.

The following describes how to measure the integral performance param-

eters, i.e. ﬂow, head, power consumption, NSPH and forces. For characteri-

sation of motors see the Motor compendium (Motor Engineering, R&T). For

ﬂow ﬁeld measurements consult the specialist literature, e.g. (Albrecht,

2002).

Figure 6.1: Velocity ﬁeld in impeller measured

with PIV.