27
There are three typical sources of sound
and vibration in refrigeration and air
conditioning systems that design and
service engineers encounter:
sound radiation:
This generally takes an airborne path.
Mechanical vibrations:
These generally extend along the parts
of the unit and the structure where it is
mounted.
gas pulsation:
This tends to travel through the
cooling medium, i.e. the refrigerant.
The sections that follow will focus on
the causes of sound from these sources
and measures to take to prevent it.
sound and ViBRation ManageMent
compressor sound radiation
Sound radiates through the air in all
directions from the compressor.
The Performer® scroll compressor
is designed for quiet operation.
Compared to most other compressors,
the Performer® generates sound at
higher frequency. High frequency
sound lacks the penetrating power
of lower frequencies and is easier to
quiet.
Use of sound insulation materials on
the inside surface of unit panels is
an effective means of substantially
reducing sound transmitted to the
outside. Ensure that no components
that might transmit sound or vibration
come into direct contact with any
uninsulated parts on unit walls.
Because of the Performer’s unique
design, with its motor cooled entirely
by suction gas, the compressor can be
insulated across its entire operating
range. Acoustic hoods are available
from Danfoss as accessories. These
hoods are easy to install quickly and
do not greatly increase the overall size
of the compressor. Refer to page 35 for
sound attenuation hoods and code
numbers.
Mechanical vibrations
Vibration
is
most
effectively
controlled by isolation. Performer®
scroll compressors are designed to
produce minimal vibration during
operation. Rubber isolaters on the
compressor base plate or on the frame
of a manifolded unit are effective
in reducing vibration transmitted
from the compressor(s) to the unit.
Rubber grommets are supplied with
all Performer® compressors. Properly
mounted, the supplied grommets
hold transmitted vibration from the
compressor to a strict minimum.
It is also extremely important that
the frame supporting the compressor
be of sufficient mass and stiffness to
help dampen vibration that could
be transmitted to the frame. For
further information on mounting
requirements, please refer to the
section on mounting assembly.
Tubing should be designed for
three dimensional flexibility, to
reduce transmission of vibration to
other structures, and to withstand
vibration without damage. For more
information on piping design, please
see the section entitled "Essential
piping design considerations" p. 23.
gas pulsation
The Performer® scroll compressor
have been designed and tested
to ensure that gas pulsations are
minimized at the most commonly
encountered air conditioning pressure
ratio. In heat pump applications and
other installations where the pressure
ratio is beyond the typical range,
testing should be conducted under
all expected conditions and in all
operating configurations to ensure
that minimum gas pulsations occur.
If the level is unacceptable, install a
discharge muffler with appropriate
resonant volume and mass. This
information can be obtained from the
muffler manufacturer.
sound generation in
a refrigeration / air
conditioning system
Summary of Contents for Performer SM Series
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