Ound And Vibration Management; Starting Sound Level; Running Sound Level; Stopping Sound Level - Danfoss MLM Series Application Manuallines

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PPLICATION UIDELINES

Starting sound level

Running sound level

Stopping sound level

Sound generation in a
refrigeration system

Compressor sound radiation

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OUND AND VIBRATION MANAGEMENT

During start-up transients it is natural for the
compressor sound level to be slightly higher than
during normal running. MLZ/MLM scroll com-
pressors exhibit very little increased start-up tran-
sient sound. If a 3-phase model is miswired, the
compressor will run in reverse. Reverse compres-
MLZ/MLM are designed with features to reduce
the sound level when a compressor is running.
Model
Sound power (dBA)
Without jacket
MLZ/MLM015 65
MLZ/MLM019 65
MLZ/MLM021 65
MLZ/MLM026 67
MLZ/MLM030 70
MLZ/MLM038 71
MLZ/MLM042 71
MLZ/MLM045 71
MLZ/MLM048 72
MLZ/MLM058 74
MLZ/MLM066 74
MLZ/MLM 076 74
MLZ/MLM have a unique discharge valve design
that minimizes stopping noise. This results in very
low shutdown sound.
Typical sound and vibration in refrigeration sys-
tems encountered by design and service engi-
neers may be broken down into the following
three source categories.
Sound radiation: This generally takes an air-
borne 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 MLZ/MLM scroll compressors are designed to
be quiet and the frequency of the sound gener-
ated 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.
FRCC.PC.015.A4.02
sor rotation is characterized 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.
Sound levels are at rated (medium temperature)
conditions.
50 Hz
Sound power (dBA) Sound power (dBA)
With jacket Without jacket
57
57
57
59
62
63
63
63
64
66
66
66
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 will focus on the causes
and methods of mitigation for each of the above
sources.
Use of sound-insulation materials on the inside
of unit panels is an eff ective means of substan-
tially 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 unique design of a full-suction gas
& oil cooled motor, compressor body insulation
across its entire operating range is possible.
60 Hz
Sound power (dBA)
With jacket
68 60
68 60
68 60
70 62
73 65
74 66
74 66
74 66
75 67
77 69
77 69
77 69
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