Technical data

SUCTION PIPING
L
NPSHA must always exceed NPSUR as shown
on Goulds performance cunres received with
order. (Reference Hydraulic Institute for NPSH
and pipe friction values needed to evaluate
suction piping.
Properly installed suction piping is a necessity for
trouble-free pump operation. Suction piping should be
flushed BEFORE connection to the pump.
1.
2.
3.
4.
5.
#PC”;
6.
Use of elbows close to the pump suction flange
should be avoided. There should be a minimum
of 2 pipe diameters of straight pipe between the
elbow and suction inlet. Where used, elbows
should be long radius.
Use suction pipe one or two sizes larger than the
pump suction, with a reducer at the suction
flange. Suction piping should never be of smaller
diameter than the pump suction.
Reducers, if used, should be eccentric, at the pump
suction flange, with sloping side down.
Pump must never be throttled on suction side.
Suction strainers, when used, must have a net “free
area” of at least three times the suction pipe area.
Separate suction lines are recommended when
more than one pump is operating from the same
source of supply.
Suction lift conditions
1. Suction pipe must be free from air pockets.
2. Suction piping must slope upwards to pump.
3. All joints must be air tight.
4. A means of priming the pump must be provided,
such as a foot valve.
Suction head/Flooded suction conditions
1. An isolation valve should be installed in the suction
line at least two pipe diameters from the suction
to permit closing of the line for pump inspection
and maintenance.
2. Keep suction pipe free from air pockets.
3. Piping should be level or slope gradually downward
from the source of supply.
4. No portion of the piping should extend below pump
suction flange.
5. ihe size of entrance from supply should be one or
two sizes larger than the suction pipe.
6. The suction pipe must be adequately submerged
below the liquid surface to prevent votices and air
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entrainment at the supply.
DISCHARGE PIPING
1. Isolation and check valves should be installed in
discharge line. Locate the check valve between
isolation valve and pump, this will pennit
inspection of the check valve. The isolation valve
is required for priming, regulation of flow, and for
inspection and maintenance of pump. ‘The check
valve prevents pump or seal damage due to
reverse flow through the pump when the driver is
turned off.
2. Increasers, if used, should be placed between pump
and check valves.
3. Cushioning devices should be used to protect the
pump from surges and water hammer if
quick-closing valves are installed in system.
FINAL PIPING CHECK
After connecting the piping to pump:
1. Rotate shaft several times by hand to lbe sure that
there is no binding and all parts are free.
2. Check alignment, per the alignment procedure
outlined previously to determine absence of pipe
strain. If pipe strain exists, correct piping.