Check
Explanation/comment
Checked
Assure adequate insulation is applied for
liquids with specific gravity less than 0.60.
To assure sufficient NPSHa.
Liquid source below the pump
Check
Explanation/comment
Checked
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 suction piping slopes up-
wards from the liquid source to the pump
inlet.
—
If the pump is not self-priming, check that a
device for priming the pump is installed.
Use a foot valve with a diameter that is at least equiva-
lent to the diameter of the suction piping.
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 close to the pump suction inlet
Correct
Incorrect
The correct distance between the inlet flange of the
pump and the closest elbow must be at least five pipe di-
ameters.
4.6 Piping checklists
38
Model 3700i API610 / Type OH2 Installation, Operation, and Maintenance Manual
