Goulds Pumps 3420 - IOM - Manual (Page 26)

s
! WARNING
Never draw piping into place by forcing at the flanged
connections of the pump. This may impose dangerous
strains on the unit and cause misalignment between
pump and driver. Pipe strain will adversely effect the
operation of the pump resulting in physical injury and
damage to the equipment.
1. All piping must be supported independently of, and
line up naturally with, the pump flanges.
2. Piping runs should be as short as possible to minimize
friction losses.
3. DO NOT connect piping to pump until grout has
hardened and pump and driver hold-down bolts have
been tightened.
4. It is suggested that expansion loops or joints be
properly installed in suction and/or discharge lines
when handling liquids at elevated temperatures, so
linear expansion of piping will not draw pump out of
alignment.
s
! WARNING
All expansion joints should be properly supported,
anchored, and restrained. Failure to do so may result
in serious physical injury if the expansion joint fails.
5. The piping should be arranged to allow pump flushing
prior to removal of the unit on services handling
corrosive liquids.
6. Carefully clean all pipe parts, valves and fittings, and
pump branches prior to assembly.
SUCTION PIPING
s
! WARNING
NPSH
A
must always exceed NPSH
R
as shown on Goulds
performance curves 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. Use of elbows close to the pump suction flange should
be avoided. There should be a minimum of two pipe
diameters of straight pipe between the elbow and
suction inlet. Where used, elbows should be long
radius.
2. If an elbow must be used at the suction flange, it must
be in the vertical position only. If an elbow must be
used in other than a vertical position, it is permissable
only by providing a minimum of two diameters of
straight pipe between the elbow and the pump suction
flange.
3. 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.
4. Reducers, if used, should be eccentric, at the pump
suction flange, with sloping side down.
5. Pump must never be throttled on suction side.
6. Suction strainers, when used, must have a net “free
area” of at least three times the suction pipe area.
7. 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. The 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 vortices and air
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 permit 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.
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3420 IOM 08/09
A