APPLICATION GUIDELINES
FRCC.PC.007.B5.02
37
SOUND AND VIBRATION MANAGEMENT
Typical sound and vibration in refrigeration and
air conditioning systems encountered by design
and service engineers may be broken down into
the following three source categories.
Sound radiation: this generally takes an airborne
path.
Mechanical vibrations: these generally extend
along the parts of the unit and structure.
Gas pulsation: this tends to travel through the
cooling medium, i.e. the refrigerant.
The following sections focus on the causes and
methods of mitigation for each of the above
sources.
SH compressors are equipped with a discharge
valve which closes at compressor shut down and
thus prevents the compressor from running back-
wards. This reduces the stopping sound to a me-
tallic click caused by the closing valve.
When the pressure diff erence or gas fl ow at shut
down should be very low, this can delay the dis-
charge valve from closing and lead to a longer
noise duration.
Sound generation in a
refrigeration or air
conditioning system
Running sound level
Stopping sound level
During start-up transients it is natural for the com-
pressor sound level to be slightly higher than dur-
ing normal running. SH scroll compressors exhibit
very little increased start-up transient sound. If a
compressor is miswired, the compressor will run
in reverse. Reverse compressor rotation is charac-
terized by an objectionable sound. To correct re-
verse rotation, disconnect power and switch any
two of the three power leads at the unit contactor.
Never switch leads at the compressor terminals.
Compressor acoustic hoods have been developed
to meet specifi c extra-low noise requirements.
The covers and bottom insulations incorporate
sound proofi ng materials and off er excellent high
and low frequency attenuation.
Starting sound level
Model
50 Hz 60 Hz
Acoustic hood
code number
Inferior hood
code n° **
Sound power
dB(A)
Attenuation
dBA
Sound power
dB(A)
Attenuation
dbA
SH090 70 6 72 6 120Z0034
Not available
SH105 71.5 6 74 6 120Z0035
SH120 72.5 6 75 6 120Z0035
SH140 * 72.5 6 76 6 120Z0035
SH161 * 73.5 6 77 6 120Z0035
SH184 75 6 78 6 120Z0135
SH180 80 6 85 4 120Z0022 120Z0353
SH240 82 6 86 4 120Z0022 120Z0353
SH300 82 6 86 4 120Z0022 120Z0353
SH380 83 6 87 4 120Z0022 120Z0353
Sound power and attenuation are given at ARI conditions, measured in free space
* For SH140 code 3 and SH161 code 3 use acoustic hood reference 120Z0135
** Inferior hood is provided in surface sump heater accessories for SH180-240-300-380 models.
Materials are UL approved and RoHS compliant
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