Suction-Piping Checklist - Goulds Pumps 3700 Installation, Operation And Maintenance Manual

Installation
Example: Installation for expansion
Correct
This illustration shows a correct installation for
expansion:
1. Expansion loop/joint

Suction-piping checklist

Performance curve reference
Net positive suction head available (NPSH
shown on the published performance curve of the pump.
Suction-piping checks
Check
Check that the distance between the
inlet flange of the pump and the closest
elbow is at least five pipe diameters.
Check that elbows in general do not
have sharp bends.
Check that the suction piping is one or
two sizes larger than the suction inlet of
the pump.
Install an eccentric reducer between
the pump inlet and the suction piping.
Check that the eccentric reducer at the
suction flange of the pump has the
following properties:
• Sloping side down
• Horizontal side at the top
Suggested suction strainers are used.
Check that they are at least three times
the area of the suction piping.
Monitor the pressure drop across the
suction strainer.
An increased pressure drop across the
strainer of 5 psi (34.5 kPa) indicates
that the strainer should be removed
and cleaned.
After a period of time (24 hours mini-
mum) system flushing should be com-
plete and the suction strainer can be
removed.
32 Model 3700, API Type OH2 / ISO 13709 1st and 2nd Ed. / API 610 8/9/10/11th Ed. Installation, Operation, and Maintenance
Incorrect
This illustration shows an incorrect installation for
expansion:
) must always exceed NPSH required (NPSH
A
Explanation/comment
This minimizes the risk of cavitation in the
suction inlet of the pump due to turbulence.
See the Example sections for illustrations.
See the Example sections for illustrations.
—
The suction piping must never have a smaller
diameter than the suction inlet of the pump.
See the Example sections for illustrations.
See the example illustrations.
Suction strainers help to prevent debris from
entering the pump.
Mesh holes with a minimum diameter of 1/16 in.
(1.6 mm) are recommended.
Liquids with specific gravity less than 0.60 a
pressure drop across the suction strainer may be
due to ice buildup. Ice buildup can cause turbu-
lence, low pressure areas and pumpage vapor-
ization.
) as
R
Checked
Manual