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AB243586442172en-001401
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
backwards. This reduces the stopping sound to a
metallic click caused by the closing valve.
When the pressure difference or gas flow at shut
down should be very low, this can delay the
discharge 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 compressor sound level to be slightly
higher than during 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 characterised by an
objectionable sound. To correct reverse 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 specific extra-low noise
requirements.
The acoustic hoods incorporate sound proofing
materials and offer excellent high and low
frequency attenuation.
Starting sound level
Model
50 Hz
60 Hz
Acoustic hood
code number
Sound power
dB(A)
Attenuation
dBA
Sound power
dB(A)
Attenuation
dbA
SH090
70
6
72
6
120Z0034
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
SH240
82
6
86
4
120Z0022
SH295
82
6
86
4
120Z0022
SH380 **
83
6
87
4
120Z0022
SH485
89
4
91
4
120Z0022
Sound power and attenuation are given at ARI conditions, measured in free space
Data given for motor code 4 compressor, for full data details refer to online datasheet generator: www.danfoss.com/odsg
* For SH140 code 3 and SH161 code 3 use acoustic hood reference 120Z0135
** For SH380 code 3 use acoustic hood reference 120Z0579
Attenuation given with acoustic
Materials are UL approved and RoHS compliant
Application Guidelines
Summary of Contents for SH485
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