Technical Data; Operating Conditions - Grundfos NBS Serie Notice D'installation Et De Fonctionnement

11. Technical data

11.1 Operating conditions

11.1.1 Ambient temperature and altitude
The ambient temperature and the installation altitude are important
factors for the motor.
All motors are able to operate without power derating for
temperatures up to +104 °F (+40 °C) or below altitude of 3280.8 ft
(1000 m) above sea level. Above these two limits, it may be
necessary to use a motor with a higher output, or de-rated. Contact
the motor manufacturer if the motor is to be operated above these
limits.Consult the motor manufacturer before operating the motor
above these limits.
11.1.2 Liquid temperature
Liquid temperature: -10 to 284 °F (-25 to +140 °C).
The maximum liquid temperature is stated on the pump nameplate,
and depends on the shaft seal chosen.
11.1.3 Maximum operating pressure
Do not exceed the maximum operating pressure stated on
the pump nameplate.
1
2
3
Pressures in the pump
Pos. Description
Maximum operating pressure, that is pressure above
1
atmospheric pressure
2 Pump pressure
3 Inlet pressure
The total value of the inlet pressure and the pump pressure must be
lower than the maximum operating pressure stated on the pump
nameplate. Operation against a closed valve gives the highest
operating pressure.
11.1.4 Minimum inlet pressure
Monitor the minimum inlet pressure to avoid cavitation. The risk of
cavitation is higher in the following situations:
• The liquid temperature is high.
• The flow rate is considerably higher than the rated flow rate of
the pump.
• The pump is operating in an open system with suction lift.
11.1.5 Maximum inlet pressure
The total value of the inlet pressure and the pump pressure must be
lower than the maximum operating pressure stated on the pump
nameplate. Operation against a closed valve yields the highest
operating pressure.
11.1.6 Minimum flow rate
The pump must not run against a closed valve as it causes an
increase in temperature and a formation of steam in the pump. That
may result in shaft damage, impeller erosion, short life of bearings
and damage to the stuffing boxes or mechanical shaft seals due to
stress or vibration. The continuous stable flow rate must be at least
10 % of the rated flow rate. The rated flow rate is stated on the
pump nameplate.
11.1.7 Maximum flow rate
Do not exceed the maximum flow rate, otherwise there is a risk of
cavitation or overload, for instance.
The minimum and maximum flow rates are indicated either on the
performance curve pages in the relevant data booklets, or on a
curve for a specific pump when selecting it in the Grundfos Product
Center. See www.grundfos.com.
H
(m)
38
32
A
28
24
20
16
12
8
4
0
0 5 10 15
Example from Grundfos Product Center in www.grundfos.com
showing minimum and maximum flow rate
Pos. Description
A Minimum flow rate
B Maximum flow rate
NBG 50-32-160/163, 50Hz
Pumped liquid = Water
o
Liquid temperarure = 20 C
Density = 1000 kg/m 3
B
20 15 30 Q(m /h) 3
21