Eng
lish (US)
24
10.1.3 Maximum flow rate
See pump performance curve in Grundfos Product Center. For all
refrigerants, please observe the increased values for NPSH at
flow rates higher than the rated flow rate.
10.1.4 Minimum flow rate
The minimum flow rate is 10 % of the nominal flow rate of the
pump.
10.1.5 Minimum differential pressure
Generally, the minimum differential pressure is to be 10 psi below
the setpoint differential pressure. The absolute minimum
differential pressure is 20 % of the closed-valve pressure at 60
hz.
10.1.6 Ambient temperature and altitude
If the ambient temperature exceeds the maximum temperature
limits of the pump or the pump is installed at an altitude
exceeding the altitude values in the chart below, the motor must
not be fully loaded due to the risk of overheating.
Overheating may result from excessive ambient temperatures or
the low density and consequently low cooling effect of the air at
high altitudes. In such cases, it may be necessary to use a motor
with a higher rated output ((P
2
).
Fig. 17
Relationship between motor output (P
2
) and ambient
temperature/altitude
Example:
From fig.
it appears that P2 must be reduced to 88 % when a
pump with a NEMA premium-efficiency motor is installed 15,584
feet above sea level.
In cases where both the maximum temperature and the maximum
altitude are exceeded, the derating factors must be multiplied.
Example: 0.89 x 0.89 = 0.79.
TM
06 84
71 021
7
P2
[%]
100
90
80
70
60
50
60
80
100
120
140
160
180
T[°F]
3280
7382 11483 15584
ft
Summary of Contents for CRN-H MAGdrive
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