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

Application Guidelines

Starting sound level

Running sound level

Stopping sound level

Sound generation in a
refrigeration system and air
conditioning system
Compressor sound radiation
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AB141686422149en-US0401

Sound and vibration management

During start-up transients, it is natural for the
compressor sound level to be slightly higher
than during normal running. Danfoss scroll
VRJ scroll compressors are designed with
optimised discharge ports and wrap geometry
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VRJ scroll compressors have very low shutdown
sound due to minimal volume of discharge
volume to push scrolls in reverse at shutdown.
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
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 VRJ 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 e ective means of substantially
compressors exhibit very little increased start-up
transient sound.
to reduce the sound level when a compressor is
running.
Sound level vs Speed
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Condition (Tsat(suction) / Tsat (discharge) and speed (RPM)
Due to this small re-expansion, there is no
internal break mechanism required to prevent
reverse spin of the scroll set.
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.
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 Danfoss unique design of a full-
suction gas & oil cooled motor, compressor body
insulation across its entire operating range is
possible.
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