GENER
AL INFORMA
TION
PR
ODUC
T INFORMA
TION
INTEGR
ATION INT
O SY
STEM
ORDERING INFORMA
TION
SY
STEM DESIGN
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. Acoustic hoods are available from
Danfoss as accessories. Refer to the tables above
for sound levels, attenuation and code numbers.
2. Use of sound-insulation materials on the inside
of unit panels is also an effective mean to reduce
sound radiation.
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.
Manage sound and vibration
Mechanical vibrations
Gas pulsation
A compressor generates some vibrations
that propagate into the surrounding parts
and structure. The vibration level of a DSH
compressor alone does not exceed 120µm peak
to peak for DSH090 to DSH184, and 154µm peak
to peak for DSH240 to DSH485. However, when
system structure natural frequencies are close to
running frequency, vibrations are amplified due
to resonance phenomenon.
A high vibration level is damageable for piping
reliability and generates high sound levels.
Mitigations methods:
1. To ensure minimum vibrations transmission to
the structure, strictly follow Danfoss mounting
requirements (mounting feet, rails etc..). For
further information on mounting requirements,
please refer to section “Design compressor
mounting”.
2. Ensure that there is no direct contact (without
insulation) between vibrating components and
structure.
3. To avoid resonance phenomenon, pipings and
frame must have natural frequencies as far as
possible from running frequencies(50 or 60Hz).
Solutions to change natural frequencies are to
work on structure stiffness and mass (brackets,
metal sheet thickness or shape…)
DSH has been designed and tested to ensure
that gas pulsation is optimized for the most
commonly encountered air conditioning pressure
ratio. Manifolded compressors are equivalents to
lagged sources of gas pulsation. Therefore, pulse
level can vary during time.
Mitigations methods:
If an unacceptable level is identified, a discharge
muffler with the appropriate resonant volume
and mass can be installed.
34
FRCC.PC.045.A7.02
Summary of Contents for DSH Series
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