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Application guidelines
Running sound level
Model
Frequency RPS
30
VZH088
60
90
30
VZH117
60
90
30
VZH170
60
90
Average sound power for reference at ARI A/C conditions measured in free space.
Note: running sound level for 575V VZH is preliminary data
Sound generation in
a refrigeration or air
conditioning system
Compressor sound radiation
Mechanical vibrations
56
FRCC.PC.023.A7.22
Sound and vibration management
For all VZH models, noise level given in table doesn't include inferior hood attenuation.
200V
Without acoustic
With acoustic hood
hood (dBA)
(dBA)
70
64
78
73
86
80
73
67
82
77
88
83
72
66
84
78
95
90
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.
For sound radiating from the compressor, the
emission path is airborne and the sound waves
are travelling directly from the machine in all
directions.
The VZH scroll compressor is designed to be
quiet and the frequency of the sound generated
is pushed into the higher ranges, which not only
are easier to reduce but also do not generate the
penetrating power of lower-frequency sound.
Use of sound-insulation materials on the inside of
unit panels is an effective means of substantially
Vibration isolation constitutes the primary
method for controlling structural vibration. VZH
scroll compressors are designed to produce
minimal vibration during operations. The use of
rubber isolators on the compressor base plate or
on the frame of a manifolded unit is very effective
in reducing vibration being transmitted from
the compressor(s) to the unit. Once the supplied
rubber grommets have been properly mounted,
vibrations transmitted from the compressor base
400V
Without acoustic
With acoustic hood
hood (dBA)
(dBA)
69
62
77
72
85
79
71
64
80
75
87
81
72
65
85
78
94
89
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.
reducing the sound being transmitted to the
outside. Ensure that no components capable
of transmitting sound/vibration within the unit
come into direct contact with any non insulated
parts on the walls of the unit.
Because of the VZH unique design of a full-
suction gas-cooled motor, compressor body
insulation across its entire operating range is
possible. Acoustic hoods are available from
Danfoss as accessories. These hoods are quick
and easy to install and do not increase the overall
size of the compressors to a great extend.
plate to the unit are held to a strict minimum.
In addition, it is extremely important that the
frame supporting the mounted compressor be of
sufficient mass and stiffness to help dampen any
residual vibration potentially transmitted to the
frame.
For further information on mounting
requirements, please refer to the section on
mounting assembly.
Single compressors
575V
Without acoustic
With acoustic hood
hood (dBA)
(dBA)
72
66
79
73
88
82
72
66
82
76
91
85
77
71
85
79
95
89
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