Liquid source above the pump
Check
Explanation/comment
Checked
Check that an isolation valve is installed in
the suction piping at a distance of at least
two times the pipe diameter from the suc-
tion inlet.
This permits you to close the line during pump inspec-
tion and maintenance.
Do not use the isolation valve to throttle the pump.
Throttling can cause these problems:
•
Loss of priming
•
Excessive temperatures
•
Damage to the pump
•
Voiding the warranty
Make sure that the suction piping is free
from air pockets.
This helps to prevent the occurrence of air and cavita-
tion in the pump inlet.
Check that the piping is level or slopes
downward from the liquid source.
—
Make sure that no part of the suction pip-
ing extends below the suction flange of the
pump.
—
Make sure that the suction piping is ade-
quately submerged below the surface of
the liquid source.
This prevents air from entering the pump through a
suction vortex.
Example: Elbow (or other flow disruption) close to the pump suction inlet
Correct
Incorrect
The correct distance between the inlet flange of the
pump and the closest flow disruption (elbow, valve,
strainer, or expansion joint) must be a least five pipe di-
ameters.
1
2
D
NOTICE:
This illustration shows a correctly
installed elbow.
NOTICE:
This illustration shows an incor-
rectly installed elbow.
4.7 Piping checklists
42
XHD Installation, Operation, and Maintenance Manual
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