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3.2.3 Vibration dampers
Vibration dampers may be required to prevent pump
vibrations from being transmitted to the building or
the pipes. In order to select the right type of vibration
damper, you need this information:
• Forces transmitted through the damper.
• Motor speed. Take the motor speed into account
in the case of speed control.
• Desired dampening in %. The recommended
value is 70 %.
The choice of vibration dampers differs from
installation to installation. In certain cases a wrong
damper may increase the vibration level. Vibration
dampers must therefore be sized by the supplier of
the vibration dampers.
3.2.4 Expansion joints
Expansion joints provide these advantages:
• absorption of thermal expansion and contraction
of pipes caused by variations in liquid
temperature
• reduction of mechanical influences in connection
with pressure surges in the pipes
• isolation of structure-borne noise in the pipes
(only rubber bellows expansion joints).
Fit the expansion joints at a minimum distance of 2
pipe diameters (DN) away from the pump flange on
the inlet side. This prevents turbulence in the joints,
thus ensuring optimum inlet conditions and minimum
pressure drop on the outlet side.
At flow velocities greater than 2.4 m/s, we
recommend that you fit larger expansion joints
matching the pipes.
3.2.5 Foundation and preliminary alignment
procedure
The foundation and preliminary alignment procedure
has four steps:
1. pouring of foundation
2. shimming of base frame
3. preliminary alignment
4. grouting.
Pouring of foundation
We recommend the following procedure to ensure a
good foundation:
1. Pour the foundation without interruptions to
within 19-32 mm of the final level. Use vibrators
to ensure that the concrete is evenly distributed.
The top surface must be well scored and grooved
before the concrete sets. This provides a bonding
surface for the grout.
2. Embed anchor bolts in the concrete as shown in
fig. 4. Allow enough bolt length to reach through
grout, shims, lower base frame, nuts and
washers.
Fig. 4 Typical anchor bolt design
Let the foundation cure for several days before the
base frame is shimmed and grouted.
Do not fit expansion joints to make up for
inaccuracies in the pipes, such as centre
displacement or misalignment of flanges.
TM04 0383 0608
Bolt length
above base
frame
Thickness of
base frame
19 to 32 mm
allowance for
grout
Base frame
Top of
foundation left
rough
Pipe sleeveLugWasher
Wedges and
shims left in
place
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