Brochure
4 x D 2 x D
Valve
Pipe contraction
Pipe expansion
Pipe bend
2 x D 2 x D
100100
Grundfos builds test benches according to in-house standards where
GS241A0540 is the most significant. The test itself is in accordance with the
international standard ISO 9906.
6.2.1 Flow
To measure the flow, Grundfos uses magnetic inductive flowmeters. These
are integrated in the test bench according to the in-house standard. Other
flow measuring techniques based on orifice, vortex meters, and turbine
wheels exist.
6.2.2 Pressure
Grundfos states pump performance in head and not pressure since head is in-
dependent of the pumped fluid, see section 2.4. Head is calculated from total
pressure measured up and down stream of the pump and density of the fluid.
The total pressure is the sum of the static and dynamic pressure. The static
pressure is measured with a pressure transducer, and the dynamic pressure
is calculated from pipe diameters at the pressure outlets and flow. If the
pressure transducers up and down stream of the pump are not located at
the same height above ground, the geodetic pressure enters the expression
for total pressure.
To achieve a good pressure measurement, the velocity profile must be uni-
form and non-rotating. The pump, pipe bends and valves aect the flow
causing a nonuniform and rotating velocity profile in the pipe. The pressure
taps must therefore be placed at a minimum distance to pump, pipe bends
and other components in the pipe system, see figure 6.3.
The pressure taps before the pump must be placed two pipe diameters up-
stream the pump, and at least four pipe diameters downstream pipe bends
and valves, see figure 6.3. The pressure tap after the pump must be placed
two pipe diameters after the pump, and at least two pipe diameters before
any flow disturbances such as bends and valves.
Figure 6.3: Pressure measurement outlet
before and after the pump. Pipe diameter, D,
is the pipe’s internal diameter.
6. Pump tests