Vibration Dampening - Grundfos Fire NKF Montage- Und Betriebsanleitung

The minimum height of the foundation (h
follows if the mass of the foundation is assumed to be 1.5 times
the total mass of the pump set:
m x 1.5
system
h =
f
L x B x ρ
f f concrete
The density (ρ) of the foundation is usually taken as 2,200 kg/m
In installations where noiseless operation is particularly
important, we recommend that you use a foundation with a mass
of up to five times that of the pump set. The minimum height of
the foundation (h ) can then be calculated:
f
m x 5
system
h =
f
L x B x ρ
f f concrete
As ordinary concrete does not set shrink-freely, the resulting gap
in relation to the intended axle height of the installed pump set
must be grouted with a suitable, shrink-free hardening and high-
strength or reinforced undercast (i.e. Pagel V1 or Eurogrout
Premium) to have a force-fit connection between the base frame
and the foundation. Before grouting the undercast, the pump set
must be aligned by means of the adjusting screws used for the
base frame. See fig. 11.
Anchor bolt
Base frame
Undercast.
Height as required
or as specified by
the manufacturer.
Rough foundation.
Determine the height at site.
Fig. 11 Aligning the pump set
For grouting the undercast, make a shuttering on the raw
foundation. Mix the grouting compound according to
manufacturer instructions and pour it into the shuttering.
Wait until the specified hardening time has past before fixing the
pump set on the foundation by means of anchor bolts.
Anchor bolts are available as an accessory (P/N 97947677).
An installation on thread rods, being used for
aligning the pump set to the right height, in
connection with additional grouting of concrete
is not allowed, as the volume of the concrete
Caution
shrinks resulting in a gap between base frame
and concrete. The gap will persist even if the
pump set is fixed by means of stud bolts later on.
This will lead to increased vibrations during
operation.
16
All manuals and user guides at all-guides.com
) can be calculated as
f
3
.
Adjusting screw
Foot
Min. 130

10.3 Vibration dampening

To prevent vibrations from being transmitted to the building and
pipework, we recommend that you fit expansion joints and
vibration dampers. Figure 12 shows an example of vibration
dampening.
Vibration
damper
Fig. 12 Example of vibration dampening
Vibration dampers
To prevent vibrations from being transmitted to the building, we
recommend that you isolate the base frame of the pump set from
buildings by means of vibration dampers.
To select the correct vibration damper, the following details are
required:
• forces transferred through the damper
• the engine speed
• the desired dampening in % (recommended value: 70 %).
The selection of vibration damper differs from installation to
installation. A wrong damper may, in certain cases, increase the
vibration level. Vibration dampers should therefore be sized by
the supplier.
If the pump set is installed on a foundation with vibration
dampers, fit expansion joints on both sides of the pump.
This prevents the pump from "hanging" from the flanges.
Expansion joints
Use only metal bellows expansion joints with
Note
limiting rods for NKF pumps with VdS approval.
Expansion joints provide the following functions:
• Absorption of thermal expansion and contraction of pipework
caused by variations in liquid temperature.
• Reduction of mechanical influences in connection with
pressure surges in the pipework.
• Isolation of structure-borne noise in the pipework
(only rubber bellows expansion joints).
Expansion joints must not be installed to
compensate for inaccuracies in the pipework
Caution
system such as misalignment or the flanges not
being parallel.
Fit the expansion joints both on the suction and the discharge
sides. The distance to the pump should be at least 1 to 1 1/2 x the
nominal width DN. This prevents turbulence in the joints and
ensures optimum suction conditions and minimum pressure drop
on the discharge side of the pump.
At high water velocities (> 5 m/s), we recommend that you fit
larger expansion joints matching the pipework.
Expansion joint