Measurement report:
Elastic bearing for air conditioning
and refrigeration systems
Effective vibration isolation with Isotop SE pro and Isotop SE lightGetzner Isotop SE pro

Getzner Isotop SE lightSet-upVibration measurements were carried out with Isotop SEpro, Isotop SE light and a conventional rubber bearing toverify the structure-borne noise insulation effect of elastic equipment bearings in air conditioning and refrigeration systems.
For the purpose of the vibration excitation, the coolant
compressor was operated at rotational frequencies of30 Hz, 50 Hz and 70 Hz. The fan ran at a capacity of 30 %to maintain the cooling system.
Three geophones, installed on the floor next to the enclosure, served to measure the vibration velocity. This also
allows conclusions to be drawn regarding how the different types of bearing affect the secondary airborne noise.

Mafund® rubber bearing

Benefits— Quieter equipment thanks to vibration isolation— Reduced secondary airborne noise even in critical installation locations(e.g. roof-top installation, mezzanine floors, etc.)— Saves time and costs during installation and procurement— Reduced maintenance costs

With the excitation frequency of the compressor set at30 Hz, there were clear improvements over a wide frequency range compared to a standard Mafund® rubberbearing.

The strongest floor vibrations occurred in the 31.5 Hz
third-octave band. In comparison to the rubber bearing,
the Isotop SE pro machine bearing achieved a reduction
in vibrations of around 16 dB here, while the Isotop SE
light delivered a reduction of roughly 13 dB.

Velocity level in dB on the floor with a compressor
operating frequency of 30 Hz

Difference in velocity level on the floor compared torubber bearing

Velocity level in dB

Velocity level in dB

Measurement results

8070605040

201510530020-5100-104

6.3

1016

Isotop SE pro

2540

Isotop SE light

63100

160250400630Frequency in Hz

4Mafund®

6.3

10

Isotop SE pro

162540

63100

160

250

400630Frequency in Hz

Isotop SE light

Improvement of the insulating effect compared tothe Mafund® rubber bearing

Improvement compared to Mafund in dB

The cumulative level was applied in order to evaluate theinsulating effect over the entire frequency range. At thecompressor operating frequencies of 30 Hz, 50 Hz and70 Hz, Isotop SE pro and Isotop SE light achieved an improvement of up to 15.3 dB or 11.7 dB respectively, in comparison to the Mafund® rubber bearing.

1614

15.3

1211.71011.5

10.9

11.4

88.2
64
2
030
Isotop SE pro
Isotop SE light

5070Compressor rotational frequency in Hz

Uniform progression of the vibration amplitudes
In order to determine the formation of the vibration
amplitudes on the floor depending on the compressor
rotational frequency, the compressor was continuously
ramped up from 30 Hz to its maximum level of 70 Hz. One
ramp-up cycle took 240 seconds.

around the 33 Hz and 55 Hz range. Overall, the two Isotop
bearings from Getzner Werkstoffe demonstrated a significantly more uniform progression of the vibration amplitude,with the Isotop SE pro machine bearing consistently exhibiting the best isolating effect.

In the case of the rubber bearing, pronounced excessive
vibrations arose with compressor rotational frequencies

v / mm/s

Floating effective value of the vibration velocity on the floor
0.20

0.150.100050100150200

Isotop SE pro
Isotop SE lightMafund®

Want to find out more about the best solution for your machine?
The EquipCalc selection tool makes it easy to choose the right product for you:www.getzner.com/equipcalc

AUSTRIA — Bürs GERMANY — Berlin — Munich — Stuttgart FRANCE — Paris — Lyon JAPAN — Tokyo INDIA — Pune
JORDAN — Amman CHINA — Beijing USA — Charlotte AUSTRALIA — Melbourne
www.getzner.com

250
Time / sMR elastic bearing for air conditioning and refrigeration systems en© Copyright by Getzner Werkstoffe GmbH | 06-2021 | Subject to change without notice.

0.05