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Section E - Piping
Piping should be arranged to allow pump flush-
ing prior to removal of the unit on services han-
dling corrosive liquids.
When PTFE or similar lined pipe is used, flange
alignment should be carefully checked. Spacer
ring gaskets are recommended to assure paral-
lel alignment of pipe and pump flanges. The fol-
lowing flange bolt torque values should be used:
1” (6-8 ft-lbs), 1-1/2” (9-12 ft-lbs), 2” (18-24
ft-lbs), 2 1/2” (20-27 ft-lbs), 3” (23-30 ft-lbs).
Piping should be supported independently from
the pump and line up naturally to the pump
flanges.
Properly sized pressure gauges should be in-
stalled in both the suction and discharge piping.
The gauges will enable the operator to easily
observe the operation of the pump, and deter-
mine if the pump is operating in conformance
with the performance curve. If cavitation or
other unstable operation should occur, widely
fluctuating discharge pressure will be noted.
GENERAL GUIDELINES
SUCTION PIPING
Reducers, if used, should be eccentric and in-
stalled at the pump suction flange with eccentric
side on the bottom.
The length of the suction pipe should be kept to
a minimum.
Suction piping should be installed with a gradual
rise to the pump to eliminate any air pockets.
Elbows or fittings should be avoided at the suc-
tion flange. Allow at least 10 pipe diameters in
length for straight run into the pump.
If a valve is used in the suction, use only full flow
valves. These valves should be for shut-off only
when the pump is not running, not for throt-
tling or controlling flow. A valve designed for
flow control should be installed in the discharge.
This valve line can be used for throttling.
Suction strainers, when used, must have a net
free area of at least three times the suction pipe
area. Inspect suction strainers regularly and
clean/replace as needed.
The diameter of the suction pipe should always
be as large or larger then the pump suction.
An isolation valve should be installed in the suc-
tion line at least two pipe diameters from the
suction to permit closing of the line for pump
inspection and maintenance.
DISCHARGE PIPING
Isolation and check valves should be installed in
the discharge line. Isolation valve allows regu-
lation of flow and for inspection of the pump.
A check valve prevents pump damage due to
water hammer.
It is good practice to install a throttling type shut
off valve in the discharge piping. Throttling the
discharge during initial start-up is recommend-
ed to protect against “water hammer,” which is
most likely when using long pipe runs at high
flow velocity.
CAUTION
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