22
SOUND AND VIBRATION MANAGEMENT
Compressor
model
Sound power level*
at 50 hz dB(A)
Sound power level*
at 60 Hz dB(A)
Acoustic
hood
code no.
without hood
with hood
without hood
with hood
NTZ048
72
65
75
68
7755001
NTZ068
70
64
74
68
NTZ096
78
71
82
74
7755002
NTZ108
76
69
80
75
NTZ136
77
71
80
75
NTZ215
84
78
88
81
7755003
NTZ271
84
78
88
81
(*) Operating conditions: R404A, Evap. temp.: -35°C, Cond. temp.: 40°C, 400 V / 50Hz
Sound produced by a compressor is
transmitted in every direction by the
ambient air, the mounting feet, the
pipework and the refrigerant in the
pipework. The easiest way to reduce
the sound transmitted through ambi-
ent air is to fi t an acoustic hood acces-
sory. Because Maneurop® NTZ com-
pressors are 100% suction gas cooled
and require no external cooling they
can be insulated or enclosed in a sound
proofi ng material lined compartment.
Sound transmitted by mounting feet,
pipework and refrigerant should be
treated the same way as vibration (see
next section).
Sound
Compressors in operation are one of
the sources of sound and vibration in
a refrigeration system. Both phenom-
ena are closely related.
Vibration
The mounting grommets delivered
with the compressor should always
be used. They will largely attenuate
the compressor vibration transmit-
ted to the base frame. These rubber
grommets have been selected and
calculated in accordance with the vi-
bration frequencies that are typical for
the compressor. For that reason other
grommet types or brands shall not be
used.
The base on which the compressor is
mounted should be suffi
ciently rigid
and of adequate mass to ensure the
full eff ectiveness of the mounting
grommets. The compressor should
never be rigidly mounted to the base
frame otherwise high vibration trans-
mission would occur and the service
life reduced. Suction and discharge
lines must have adequate fl exibility in
3 planes. Eventually vibration absorb-
ers may be required.
Vibration is also transmitted by the
refrigerant gas. Maneurop® NTZ com-
pressors have built-in muffl
ers to re-
duce pulsation. To further reduce vi-
bration an extra discharge line muffl
er
can be installed.
