
Manage sound and vibration
Typical sounds and vibrations in systems can be
broken down into the following three categories:
• Sound radiation (through air)
• Mechanical vibrations (through parts and
structure)
• Gas pulsation (through refrigerant)
The following sections focus on the causes and
methods of mitigation for each of the above
sources.
Compressor sound
radiation
For sound radiating from the compressors,
the emission path is air and the sound waves
are travelling directly from the machine in all
directions.
Sound levels are as follows:
• For compressors running alone:
Compressor model
50 H
z
60 H
z
Acoustic hood
code number
Sound power
dB(A)
Attenuation
dBA
Sound power
dB(A)
Attenuation
dBA
HRM025-038
66
5
69
5
120Z5043
HRM040-047
67
5
70
5
120Z5043
HRM048-054
68
5
71
5
120Z5044
HRM058-060
69
5
72
5
120Z5044
HLM068-081
70
5
73
5
120Z5044
HCM094
71
5
74
5
120Z5045
HCM109-120
74
5
78
5
120Z5045
HRH029-032
65
5
68
5
120Z5043
HRH034-040
66
5
69
5
120Z5043
HRH041-054
67
5
70
5
120Z5044
HLH061
70
5
73
5
120Z5044
HLH068-HLJ083
71
5
74
5
120Z5044
HCJ090-105-120
72
5
75
5
120Z5045
HCJ091-106-121
73
5
76
5
120Z5045
Attenuation given with acoustic hood only
Materials are UL approved and RoHS compliant
Sound power and attenuation are given at ARI conditions, measured in free space
H*P series same as H*M series
Note: During compressor shut down, a short
reverse rotation sound is generated. The duration
of this sound depends on the pressure difference
at shut down and should be less than 3 seconds.
This phenomenon has no impact on compressor
reliability.
Mitigations methods:
We can consider two means to reduce
compressors sound radiations:
1. Acoustic hoods are quick and easy to install
and do not increase the overall size of the
compressors to a great extent. Acoustic hoods
are available from Danfoss as accessories. Refer to
the table above for sound levels, attenuation and
code numbers.
2. Use of sound-insulation materials on the inside
of unit panels is also an effective means to reduce
radiation.
26
FRCC.PC.012.A7.02
GENER
AL INFORM
ATION
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ODUC
T INFORM
ATION
INTEGR
ATION INT
O SY
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STEM DESIGN