installation &
operating instructions
Design Envelope 4312 and 4392 vertical in-line
twin pumping unit with ivs drive
5
• Do not rigidly connect the pump to a permanent base
(See fig. 1.7 on page 6) Note: if the pump must be
connected to a permanent base, the pump must be iso-
lated from the piping by flexible connectors and the base
isolated from the building structure on an inertia base.
• Do not install the unit with the shaft horizontal.
• Do not support the installed unit by the motor eye bolts
or by supports to any other part of the pump other than
stated above.
important
All Design Envelope 4312 pumps contain a tapped hole in the
motor bracket above the discharge flange for draining the
well. Pipe this drain hole to a floor drain to avoid overflow of
the cavity caused by collecting chilled water condensate or
from seal failure.
1.2.4 pump piping – general
Never connect a pump to piping, always start piping
from pump.
Use as few bends as possible and preferably long radius
elbows.
Do not use flexible connectors on the suction or discharge.
Make sure piping exerts no strain on pump as this would dis-
tort the casing and cause pump misalignment.
Suction and discharge pipes may be increased at pump noz-
zle to suit pump capacity and particular conditions of installa-
tion. Use eccentric reducers on suction connection.
Lay out the suction line with a continual rise towards the
pump without high points, thus eliminating possibility of air
pockets that may prevent the pump from operating.
A strainer of three or four times the area of the suction pipe,
installed in the suction line, will prevent the entrance of for-
eign materials into the pump. V" (3mm) diameter perfora-
tions in the strainer are typical.
Test suction line for air leaks before starting; this becomes
essential with long suction line or static lift.
Install, at pump suction, a straight pipe of a length equiva-
lent to 4 or 6 times its diameter; this becomes essential
when handling liquids above 120°f (49°c). Armstrong suction
guides may be used in place of the straight pipe run and in
line strainer.
Install isolation valve in both suction and discharge lines on
flooded suction application; this valve is used mainly to iso-
late the pump for inspection or repair.
Install a non-slam check valve in discharge line between
pump and isolation valve to protect pump from excessive
back pressure and to prevent water running back through the
pump in case of driver failure. Armstrong Flo-Trex valve may
be used in place of check valve and isolation valve on pump
discharge.
caution
Discharge valve only must be used to reduce the
pump flow, not the suction valve.
Care must be taken in the suction line layout and
installation, as it is usually the major source of con-
cern in centrifugal pump applications.
important
Do not run the pump for any length of time under very low
flow conditions or with the discharge valve closed. To do so
could cause the water in the casing to reach super heated
steam conditions and will cause premature failure and could
cause serious and dramatic damage to the pump and sur-
rounding area.
note:
The pumping unit is accurately aligned at the factory prior to
being shipped.
Alignment on the Design Envelope 4312 twin may be verified
by assuring an equal gap between coupling halves on both
sides of the coupling.
fig. 1.1 hanger supported pipe mounted
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