Danfoss VRJ Application Manuallines page 19

Application Guidelines
Mechanical vibrations
Speed bypass
Gas pulsation
Sound and vibration management
Vibration isolation constitutes the primary
method for controlling structural vibration. VRJ
scroll compressors are designed to produce
minimal vibration during operations. The use
of rubber isolators on the compressor base
plate is very e ective in reducing vibration
being transmitted from the compressor to
the unit. Rubber grommets are supplied with
all Danfoss compressors. Once the supplied
rubber grommets have been properly mounted,
vibrations transmitted from the compressor base
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 su cient mass and sti ness to help dampen
any residual vibration potentially transmitted to
the frame. The tubing should be designed so as
If vibrations still occur at some typical
frequencies, a speed bypass function is available
within the VRJ. This function allows avoiding
The VRJ scroll compressor has been designed
and tested to ensure that gas pulsation has been
optimised for the most commonly encountered
air conditioning pressure ratio. On heat pump
installations and other installations where the
pressure ratio lies beyond the typical range,
testing should be conducted under all expected
to both reduce the transmission of vibrations to
other structures and withstand vibration without
incurring any damage. Tubing should also be
designed for three-dimensional exibility.
During unit development, the complete
compressor speed range should be covered, in
order to de ne if abnormal vibrations occur or
not. As ultimate solution, speed bypass can be
applied.
For more information on piping design, please
see the section entitled "Essential piping design
considerations".
some frequency ranges and avoiding vibrations
to occur. Refer to "Danfoss VRJ Installation and
Operation instructions" for setting details.
conditions and operating con gurations to
ensure that minimum gas pulsation is present. If
an unacceptable level is identi ed, a discharge
mu er with the appropriate resonant volume
and mass should be installed. This information
can be obtained from the component
manufacturer.
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