Functions
MAGNA3
4
24
Flow estimation accuracy
The internal sensor estimates the difference in
pressure between the inlet and outlet port of the pump.
The measurement is not a direct differential-pressure
measurement, but by knowing the hydraulic design of
the pump, you can estimate the differential pressure
across the pump. The speed and power are also used
to give a direct estimation of the current duty point of
the pump.
The calculated flow rate has an accuracy specified as
± xx % of Q
max
. The less flow through the pump, the
less accurate the reading will be. The typical accuracy
of the flow reading is ± 5 % of the specific pump’s
maximum flow. In extreme cases, such as closed valve
operation, the accuracy can be up to ± 10 % of the
maximum flow.
See also Heat energy monitor, page 26.
Example:
Fig. 31 Q
max
1. MAGNA3 65-60 has a Q
max
of 40 m
3
/h. A typical 5
% accuracy means 2 m
3
/h inaccuracy of Q
max
. ± 2
m
3
/h.
2. This accuracy is valid for the entire QH area. If the
pump indicates 10 m
3
/h, the measurement is 10 ± 2
m
3
/h.
3. The flow rate can be 8-12 m
3
/h.
4. Note: Use of a water/ethylene glycol mixture will
decrease the accuracy.
TM05 2448 5111
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