Operating Conditions
Ambient Temperature and Altitude
The ambient temperature and the installation altitude are important factors for the motor life as they affect the life of the bearings and the insulation system.
If the ambient temperature exceeds the recommended maximum ambient temperature or the installation altitude exceeds the recommended maximum altitude above sea level, see fig. 6, the motor must not be fully loaded due to the low density and consequently low cooling effect of the air. In such cases, it may be necessary to use a motor with a higher output.
Liquid Temperature
-40 - +140 °C.
The maximum liquid temperature is stated on the pump nameplate. It depends on the shaft seal chosen.
For EN-GJL-250 cast-iron pump housings, local regulations may not allow liquid temperatures above +120 °C.
Maximum Operating 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.
Minimum Inlet Pressure
Pay attention to the minimum inlet pressure to avoid cavitation. The risk of cavitation is higher in the following situations:
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The liquid temperature is high.
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The flow rate is considerably higher than the pump's rated flow rate.
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The pump is operating in an open system with suction lift.
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The liquid is sucked through long pipes.
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The inlet conditions are poor.
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The operating pressure is low.
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.
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.
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.
Shaft Seals
The operating range of the seals is described for two main applications: Pumping of water or pumping of coolants.
Seals with a temperature range of 0 °C and up are mainly used for pumping water, while seals for temperatures below 0 °C are mainly intended for coolants.
We do not recommend that you operate the pump at maximum temperature and maximum pressure at the same time as the seal life will be reduced and periodic noise will occur.