Brochure

Possible cause What to examine How to find the error
The catalogue curve does not
reflect the 0-series testen.
Compare 0-series test with
catalog curve
If the catalogue curve and
0-series test do not correspond,
it can not be expected that the
pump performs according to
the catalogue curve.
The impeller diameter or outlet
width is bigger than on the
0-series
Make a scaling of the test where
the impeller diameter D2 is
reduced until the power matches
most of the curve. If the head
also matches the curve, then the
diameter on the produced pump
is probably too big. Repeat the
same procedure with the impeller
outlet width b2. Scaling of D2
and b2 is discussed in chapter 4.5
Make sure that the right impeller
is tested.
Measure the impeller’s outlet on
the 0-series pump.
Adjust impeller diameter and
outlet width in the production
Mechanical drag is found
Remove the mechanical drag
The motor efficiency is lower
than specified.
Separate motor and pump. Test
them separately. The pump can
be in a test bench with torque
meter or with a calibrated motor.
If the pump’s power consumption
is ok, the motor is the problem.
Find cause for motor error.
Listen to the pump. If it is noisy,
turn off the pump and rotate by
hand to identify any friction.
Look at the difference of the
two power curves. Is it constant,
there is probably drag.
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Table 1: The test shows that the power consumption for a produced pump lies
above the catalogue value but the head is the same as the catalogue curve.
B. Check of test results