Engineering manual - SAB 193-233-283 S A-frame (including ATEX)
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Note:
When installing a compressor unit on other floors than the lowest, consider that floors
suspended by steel beams tend to have a higher natural frequency and carry vibrations better.
This means that the installation should be done on either a sufficiently heavy elevated concrete
slab with machine shoes, or the unit should be installed on suitable dampers. See subsection
7.22 below for details on the elevated concrete slab.
7.22
Mass damping between unit and building
Some places have particularly strict requirements to prevent vibrations from propagating to the
building construction itself and causing noise nuisance, thus certain measures must be taken.
To avoid vibrations from the unit being transferred to the building, the compressor unit can be
mounted directly on a foundation block which is isolated from the building.
The foundation block is cast as an independent unit as shown in Fig. 77.
Fig. 77: Foundation block
This foundation block is cast directly on a firm and supporting bedding and is isolated from the
machine floor by means of approximately 20 mm thick plates, made of e. g. high density
polystyrene.
If the bedding is part of the cast building construction, the foundation block can be cast on a vi-
bration mat with a suitable bearing capacity. This should be taken into account by the supplier.
The dead weight of the foundation block must be in accordance with the weight of the unit.
Consequently, the block is cast with an outer length and width as indicated in the foundation
drawing following the order.
The height
H
of the block must be
450 mm
for all units provided that concrete with a density of
approximately 2.2 tonnes per m
3
is used.
When mounting the compressor unit on top of the block, follow the description in subsection
7.21 The general values for vibrations emitted from the unit are stated in subsection
bration data for compressors (all compressor types).
At the same time, flexible vibration eliminators should be used in the pipe connection to the unit
in order to avoid transmitting noise through the piping. Very often, it will be necessary to insu-
late the machine room against noise or to use a noise absorbing lining in the unit to prevent
noise from spreading to the environment.
If you have any questions, please contact your local Johnson Controls representative.
7.23
Damping using vibration dampers
The most efficient damping of vibrations from the unit to the foundation, and consequently to
the construction, is achieved by placing the compressor unit on vibration dampers calculated
and delivered by Johnson Controls Denmark.