Minimum Inlet Pressure; Maximum Inlet Pressure; Minimum Flow Rate; Maximum Flow Rate - Grundfos NB Serie Instrucciones De Instalación Y Funcionamiento

6.4 Minimum inlet pressure

Pay attention to 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
pump's rated flow rate.
• The pump is operating in an open system with
suction lift.
• The liquid is sucked through long pipes.
• The inlet conditions are poor.
• The operating pressure is low.

6.5 Maximum inlet pressure

The inlet pressure + 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.

6.6 Minimum flow rate

The pump must not run against a closed valve as
this will cause an increase in temperature/formation
of steam in the pump. This may cause shaft damage,
impeller erosion, short life of bearings and damage
to stuffing boxes or mechanical shaft seals due to
stress or vibration. The continuous flow rate must be
at least 10 % of the rated flow rate. The rated flow
rate is stated on the pump nameplate.
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6.7 Maximum flow rate

Do not exceed the maximum flow rate as otherwise
there is a risk of for instance cavitation and overload.
The minimum and maximum flow rates can be read
either from the performance curve pages in the
relevant data booklets or from a curve for a specific
pump when selecting it in Grundfos Product Center.
See www.grundfos.com.
Minimum flow rate
Maximum flow rate
Fig. 8 Example from Grundfos Product Center
in www.grundfos.com showing minimum
and maximum flow rate