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Using a straight-edge and a caliper :
Using a dial gauge :
When checking parallel alignment, the total indicator read-out
shown is twice the value of the actual shaft displacement.
Align in the vertical plane first, then horizontally by moving the motor.
Lifetime of ball bearing and coupling flexible part as well as pumpset
noise level will depend on the alignment quality.
Coupling alignment is not necessary when a IEC adaptation lantern is
used. Both motor and pumps shaft are aligned by construction.
7.2 PIPE WORK
7.2.1
GENERAL INFORMATION
Pump connection flanges are plugged to avoid any contamination during
transport and storage. Protective covers should be removed only before
installing the pump in the piping. Remove dust before removing the
covers from pump flanges. Especially for new pipe work : clean
thoroughly piping before connecting it to the pump.
Remove protective covers
Add flange gaskets
Fasten suction pipe
Fasten discharge pipe
No stress must be applied to the pump casing by the pipe work. If
excessive, those forces and moments cause misalignment,
overheating of bearings, coupling wear, vibrations and possible failure or
explosion of pump casing.
After replacement of a pump or during connection of pipes to
pump flanges, never use pump flanges as a support to pull or push
the pipe works.
The axial displacement of expansion coupling (if installed) should be
limited. Use tie rods as recommended by the manufacturer.
Two designs are possible for the suction line : positive suction head and
suction lift operation.
7.2.2
POSITIVE SUCTION HEAD INSTALLATION
Nominal diameter of the pipeline is often larger diameter than pump
suction flange. Unequal nominal diameter should be compensated by an
eccentric transition part. It is recommended to install a straight pipe
before the pump inlet (size L should be 2 to 3 times the pipe nominal
dimension). The suction line should be laid with a downward slope
toward the pump.
7.2.3
SUCTION LIFT INST ALLATION
A dedicated suction pipe should be installed for each pump used with a
negative suction head (suction lift).
Nominal diameter of the suction pipe must be equal or a size larger than
the pump suction flange diameter. Pipe inlet should be set below lower
liquid level. Install a strainer with foot valve to prevent priming loss. The
strainer will be installed far enough from the pit bottom to avoid
excessive suction head losses and particles intake. Ensure there is no air
intake along the suction pipe and that the suction pipe is inclined up
towards the pump inlet. Avoid air pocket creation.
Suction lift line should be laid with a rising slope towards the pump. A
straight pipe (length should be 8 to 10 times the pipe nominal diameter)
should be added in front of pump. Nominal diameter of the pipeline is at
least equal to the pump inlet size. Pipe diameter is calculated to limit
flow speed to 2m/s.
The size of the suction strainer/foot valve will be selected to ensure
minimum pressure losses in strainer and full opening of NRV at pump
nominal flow.
Check that pump required NPSH (NPSHR) is lower than system
available NPSH (NPSHA).
ACCESSORIES AND PIPE S CONNECTION
7.2.4
Discharge pipe :
Nominal diameter of discharge pipe should be chosen to ensure a max
flow speed of 3m/s.
After pipe work is done turn pump shaft by hand and check it turns
freely. If it appears that it is difficult to turn pump shaft, then check
forces applied by piping to pump casing. Installation of piping should be
done again.
Filter :
If required a filter can be installed before the pump intake. To ensure
proper working of pump the equivalent exchange surface of the strainer
should be 3 time the pipe sectional area.
Clogging level of filter should be checked regularly.
Valves :
It is advised to install isolating valves on suction and discharge side for
maintenance purpose. Those valves should be of large passage type and
could be locked in position.
Isolating valve on suction side should not be connected to pump suction
flange.
Non-return valve :
A check valve can be installed on discharge side to protect the pump
from back flow effects such as pressure surges or back flow when pump
is stopped.
External lubrication of mechanical seal :
If suction lift operation is preferred it will be necessary to check pressure
on vent connection :
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