Grundfos LS Series - Inlet Pipe Guidelines; Common Guidelines; Flooded Systems; Suction Lift Systems

English (GB)
11
3.5 Inlet pipe guidelines
3.5.1 Common guidelines
Avoid air pockets or turbulence in the inlet pipe
Never use reducers in a horizontal inlet pipe as shown in fig. 10. Instead, use an eccentric reducer as
illustrated in fig. 9.
3.5.2 Flooded systems
Closed systems and open systems where the liquid level is above the pump inlet.
3.5.3 Suction lift systems
Closed systems and open systems where the liquid level is below the pump inlet.
Install the inlet pipe sloping upwards towards the inlet port. Any high point in the pipe will be filled with air and
thus prevent proper operation of the pump. When reducing the pipe to the inlet port diameter, use an eccentric
reducer with the eccentric side down to avoid air pockets.
Correct Wrong
TM04 0093 4907 TM04 0092 4907
Fig. 9 Correctly mounted reducer Fig. 10 Reducers resulting in air pockets and
turbulence
Eccentric reducer
Turbulent flow
Air pocket
Concentric reducer
Correct
TM04 0148 4907
Fig. 11 Correctly mounted inlet pipe
Eccentric reducer
Pipe sloping down
towards pump
Correct Wrong
TM04 0098 4907 TM04 0097 4907
Fig. 12 Correctly mounted inlet pipe Fig. 13 Inlet pipe resulting in air pockets
Eccentric reducer
Pipe sloping
up towards
pump
Eccentric reducer
Air pocket
Pipe sloping
down towards
pump