Sound And Vibration Management; Starting Sound Level; Running Sound Level; Stopping Sound Level - Danfoss SH090 Application Manuallines

Application Guidelines

Starting sound level

Running sound level

Stopping sound level

Sound generation in a
refrigeration or air
conditioning system
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AB243586442172en-001301

Sound and vibration management

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 acoustic hoods have been
developed to meet specific extra-low noise
requirements.
Model
Sound power
dB(A)
SH090 70
SH105 71.5
SH120 72.5
SH140 * 72.5
SH161 * 73.5
SH184 75
SH180 80
SH240 82
SH295 82
SH380 ** 83
SH485 89
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
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.
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.
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.
The acoustic hoods incorporate sound proofing
materials and offer excellent high and low
frequency attenuation.
50 Hz
Attenuation Sound power
dBA  dB(A)
6 72
6 74
6 75
6 76
6 77
6 78
6 85
6 86
6 86
6 87
4 91
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.
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.
60 Hz
Acoustic hood
Attenuation
code number
dbA 
6 120Z0034
6 120Z0035
6 120Z0035
6 120Z0035
6 120Z0035
6 120Z0135
4 120Z0022
4 120Z0022
4 120Z0022
4 120Z0022
4 120Z0022