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6.2 Measuring pump performance
Pump performance is usually described by curves of measured head and
power consumption versus measured flow, see figure 6.2. From these meas-
ured curves, an eciency curve can be calculated. The measured pump per-
formance is used in development projects for verification of computer mod-
els and to show that the pump meets the specification.
During production, the performance curves are measured to be sure they
correspond to the catalogue curves within standard tolerances.
Flow, head and power consumption are measured during operation in a test
bench that can imitate the system characteristics the pump can be exposed
to. By varying the flow resistance in the test bench, a number of correspond-
ing values of flow, dierential pressure, power consumption and rotational
speed can be measured to create the performance curves. Power consump-
tion can be measured indirectly if a motor characteristic that contains cor-
responding values for rotational speed, electrical power, and shaft power is
available. Pump performance depends on rotational speed and therefore it
must be measured.
During development, the test is done in a number of operating points from
shut-o, i.e. no flow to maximum flow and in reversal from maximum flow
to shut-o. To resolve the performance curves adequately, 10 - 15 operating
points are usually enough.
Maintenance tests and final inspection tests are made as in house inspec-
tion tests or as certificate tests to provide the customer with documentation
of the pump performance. Here 2 - 5 predefined operating points are usally
sucient. The flow is set and the corresponding head, electrical power con-
sumption and possibly rotational speed are measured. The electrical power
consumption is measured because the complete product performance is
wanted.
Figure 6.2: Measured head and power curve
as function of the flow.