Inlet Pipe With A Horizontal Elbow In The Feed Line; Installations With Vertical Inlet Pipe In Confined Space - Grundfos LSV Montage- Und Betriebsanleitung

3.5.5 Inlet pipe with a horizontal elbow in the feed line

Make sure that the liquid flow is evenly distributed to both sides of the double-suction impeller.
There is always an uneven, turbulent flow through an elbow. See below. If you install an elbow in the inlet pipe
near the pump in a position other than vertical, more liquid will enter one side of the impeller than the other. This
will result in heavy, unbalanced thrust loads overheating the bearings, causing rapid wear and reducing the
hydraulic performance.
Correct
Recommended inlet pipe installation with a length of
straight pipe between horizontal elbow and pump
3.5.6 Installations with vertical inlet pipe in
confined space
Inlet diffuser (1) in the inlet pipe
16
3-5 x DN
1
Wrong
2
1
Pos. Description
1 Uneven flow
Water pressure increases here causing a
2 greater flow to one side of the impeller
than to the other
Unbalanced loading of a double-suction impeller due
to uneven flow through a horizontal elbow close to
the pump