Goulds Pumps 3700 Installation, Operation And Maintenance Manual page 35

Check
If more than one pump operates from
the same liquid source, check that
separate suction-piping lines are used
for each pump.
If necessary, make sure that the suc-
tion piping includes a drain valve and
that it is correctly installed.
Assure adequate insulation is applied
for liquids with specific gravity less than
0.60.
Liquid source below the pump
Check
Make sure that the suction piping is
free from air pockets.
Check that the suction piping slopes
upwards 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.
Liquid source above the pump
Check
Check that an isolation valve is in-
stalled in the suction piping at a dis-
tance of at least two times the pipe
diameter from the suction inlet.
Make sure that the suction piping is
free from air pockets.
Check that the piping is level or slopes
downward from the liquid source.
Make sure that no part of the suction
piping extends below the suction flange
of the pump.
Make sure that the suction piping is
adequately submerged below the sur-
face of the liquid source.
Example: Elbow close to the pump suction inlet
Correct
The correct distance between the inlet flange of the
pump and the closest elbow must be at least five
pipe diameters.
Model 3700, API Type OH2 / ISO 13709 1st and 2nd Ed. / API 610 8/9/10/11th Ed. Installation, Operation, and Maintenance
Manual
Explanation/comment
This recommendation helps you to achieve a
higher pump performance and prevent vapor
locking especially with specific gravity of liquid
less than 0.60.
—
To assure sufficient NPSHa.
Explanation/comment
This helps to prevent the occurrence of air and
cavitation in the pump inlet.
—
Use a foot valve with a diameter that is at least
equivalent to the diameter of the suction piping.
Explanation/comment
This permits you to close the line during pump
inspection 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
This helps to prevent the occurrence of air and
cavitation in the pump inlet.
—
—
This prevents air from entering the pump through
a suction vortex.
Incorrect
Installation
Checked
Checked
Checked
33