Goulds Pumps 3640 - IOM - Manual (Page 30)

Installation
Check Explanation/comment Checked
Use cushioning devices. This protects the pump from surges and water hammer
if quick-closing valves are installed in the system.
Alignment criteria for pump flanges
Type Criteria
Axial The flange gasket thickness is ±0.03 in. (0.8 mm).
Parallel Align the flange to be within 0.001 in./in. to 0.03 in./
in. maximum (0.025 mm/mm to 0.8 mm/mm) of the
flange diameter.
Concentric You can easily install the flange bolts by hand.
Suction-piping checklist
Performance curve reference
CAUTION:
Vary the capacity with the regulating valve in the discharge line. Never throttle the flow from the suction
side. This action can result in decreased performance, unexpected heat generation, and equipment
damage.
Net positive suction head available (NPSH
A
) must always exceed NPSH required (NPSH
R
) as
shown on the published performance curve of the pump.
Suction-piping checks
Check Explanation/comment Checked
Check that the distance between This minimizes the risk of cavita-
the inlet flange of the pump and tion in the suction inlet of the
the closest elbow is at least five pump due to turbulence.
pipe diameters.
Check that elbows in general do
—
not have sharp bends.
Check that the suction piping is
The suction piping must never
one or two sizes larger than the have a smaller diameter than the
suction inlet of the pump. suction inlet of the pump.
Install an eccentric reducer be-
tween 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
When suction strainers or suction Suction strainers help to prevent
bells are used, check that they are clogging.
at least three times the area of the Mesh holes with a minimum diam-
suction piping. eter of 1/16 in. (1.6 mm) are
recommended.
If more than one pump operates This recommendation helps you to
from the same liquid source, achieve a higher pump perfor-
check that separate suction-piping mance.
lines are used for each pump.
If necessary, make sure that the
—
suction piping includes a drain
valve and that it is correctly in-
stalled.
Liquid source below the pump
Check Explanation/comment Checked
Make sure that the suction piping This helps to prevent the occur-
is free from air pockets. rence of air and cavitation in the
pump inlet.
28 Model 3640 Installation, Operation, and Maintenance Manual