Flowserve LN - Manual (Page 13)

LN, LNE, LNH, LNV, LNEV, LNC and LNEC USER INSTRUCTIONS ENGLISH 71576423 11-09
Page 13 of 32 flowserve.com
When the electric motor has sleeve bearings it is
necessary to ensure that the motor is aligned to run
on its magnetic centreline.
Refer to the motor manual for details.
A button (screwed into one of the shaft ends) is
normally fitted between the motor and pump shaft
ends to fix the axial position.
4.5 Piping
The user must verify that the equipment is
isolated from any external sources of vibration.
Protective covers are fitted to the pipe
connections to prevent foreign bodies entering during
transportation and installation. Ensure that these
covers are removed from the pump before connecting
any pipes.
4.5.1 Suction and discharge pipe work
Never use the pump as a support for
piping.
Maximum forces and moments allowed on the pump
flanges vary with the pump size and type. To minimize
these forces and moments that may, if excessive, cause
misalignment, hot bearings, worn couplings, vibration
and the possible failure of the pump casing, the
following points should be strictly followed:
•
Prevent excessive external pipe load
•
Never draw piping into place by applying force to
pump flange connections
•
Do not mount expansion joints so that their force,
due to internal pressure, acts on the pump flange.
Ensure piping and fittings are flushed
before use.
Ensure piping for hazardous liquids is arranged
to allow pump flushing before removal of the pump.
4.5.2 Suction piping
a) The inlet pipe should be one or two sizes larger
than the pump inlet bore and pipe bends should
be as large a radius as possible.
b) On suction lift the piping should be inclined up
towards the pump inlet with eccentric reducers
incorporated to prevent air locks.
c) On positive suction, the inlet piping must have a
constant fall towards the pump.
d) Allow a minimum of two pipe diameters of
straight section between the elbow and inlet
flange.
e) Inlet strainers, when used, should have a net `free
area' of at least three times the inlet pipe area.
f) Do not install elbows at an angle other than
perpendicular to the shaft axis. Elbows parallel
to the shaft axis will cause uneven flow.
g) Except in unusual circumstances strainers are
not recommended in inlet piping. If considerable
foreign matter is expected a screen installed at
the entrance to the wet well is preferable.
h) Fitting an isolator and non-return valves can
allow easier maintenance.
i) Never throttle pump on suction side and never
place a valve directly on the pump inlet nozzle.
4.5.3 Discharge piping
A non-return valve should be located in the discharge
pipe work to protect the pump from excessive back
pressure and hence reverse rotation when the unit is
stopped.
4.5.4 Auxiliary piping
4.5.4.1 Pumps fitted with packed gland
When suction pressure is below ambient pressure it
is necessary to feed the gland packing with liquid to
provide lubrication and prevent the ingress of air.
When pumping 'dirty' liquids a clean liquid supply to
the gland is recommended.
4.5.4.2 Pumps fitted with mechanical seals
Single seals requiring re-circulation will normally be
provided with the auxiliary piping from pump casing
already fitted.
Seal housings/covers having an auxiliary quench
connection require connection to a suitable source of
liquid flow, low pressure steam or static pressure
from a header tank. Recommended pressure is 0.35
bar (5psi) or less. Check General arrangement
drawing.
Special seals may require modification to auxiliary
piping described above. Consult separate User
Instructions and or Flowserve if unsure of correct
method or arrangement.
For pumping hot liquids, to avoid seal damage, it is
recommended that any external flush/cooling supply
be continued after stopping the pump.