Measurement report:
Elastic bearing for air handlingand refrigeration systems
Effective vibration isolation of the entire unit

Complete unit with measuring points on the f loorConstruction

Benefits

In order to compare the insulation behaviour of different elastic bearings, vibration measurements werecarried out on a compact unit. The main excitation
came from both a refrigerant compressor and a fan.

— Measurable reduction in vibrations
and secondary airborne noise— Units can be installed even in difficult
locations (e.g. roofs and mezzanine floors)— Easy and convenient installation— Long service life and maintenance-free

For the purpose of the measurement, the coolant
compressor was operated at the frequencies 30 Hz,
50 Hz and 70 Hz. The fan ran at a high intensity leveland served to balance the temperature of the refrigerant system.
The vibrations transmitted from the unit to the floor
were recorded at four measuring points next to theunit. This also allows a conclusion to be drawn regarding how the different types of bearing affect thesecondary airborne noise.

Investigated bearing types
Different types of bearings were installed, in order toobtain a meaningful comparison. A standard Mafund
rubber bearing was used as a reference product.

In addition, measurements were carried out withSylomer® strips and metal-polyurethane combinations.

MafundSylomer® strip bearing

Machine mounting with Sylomer®

Isotop® SE-2

Isotop® DSD with FP/K footplate

Isotop® SD with FP/K footplate

Measurement results
With the excitation frequency of the compressor set at
50 Hz, there are clear improvements over a wide frequency range compared to a standard Mafund rubberbearing. The improvements in the critical range from20 Hz to 100 Hz are particularly striking.

Only elastic solutions that can be best matched to theoperating point exhibit a sustained effect, in particularin this frequency range. Rubber products, such as thosefrom Mafund, whose stiffness can only be selected withlimited optimisation, show no effectiveness or even an
amplification effect here compared to a fixed bearing.

7060
5040302010Sylomer® strip bearing
Without bearing
MafundIsotop® SE-2
Isotop® DSD
Isotop® SD

2500 Hz2000 Hz

1600 Hz

1250 Hz

1000 Hz

800 Hz630 Hz500 Hz400 Hz315 Hz250 Hz200 Hz

160 Hz125 Hz100 Hz

80 Hz

63 Hz

50 Hz

40 Hz

32 Hz

25 Hz

20 Hz

16 Hz

12.5 Hz

10 Hz

8 Hz

6.3 Hz

5 Hz

4 Hz

0
3.2 Hz

Velocity level in dB

Velocity level in dB at a compressor operating frequency of 50 Hz

Frequency in Hz

Both pure steel spring isolators (Isotop® SD) and steel
springs with a damper core (Isotop® DSD) show significant improvements of over 18 dB. Metal-polyurethane
combinations from the Isotop® series, but also pureSylomer® solutions, likewise demonstrate the effectiveness of Getzner's materials.

The tests have also shown that attention must be paid
to stability and sturdiness, in particular for systems witha high centre of gravity. Here, steel spring solutions withSylodamp® damper core (Isotop® DSD) or sandwich elements (Isotop® SE) are preferred to pure steel springs.

Improvement of the insulating effect compared to the Mafund rubber bearing
25 dB

20 dB
18.9 dB

18.3 dB
15 dB
14.9 dB
13.2 dB
10 dB
9.3 dB
5 dB

0 dB
Machine mounting with Sylomer®
50 HzSylomer® strip bearing

Isotop® SE-2Isotop® DSD

Isotop® SD

Compressor operating frequency: 50 Hz Measuring point: Floor

Impact excitations show that the floor has a natural frequency at about 70 Hz. Nevertheless, a significant reduction was also achieved in this range.

If the bearing comparison is extended to cover thecompressor operating frequencies of 30 Hz and 70 Hz,
a significant improvement in the insulating effect compared to the standard rubber bearing is also demonstrated here.

Improvement of the insulating effect compared to the Mafund rubber bearing
25 dB

20 dB

15 dB

11.3dB

10 dB
9.3
dB
5 dB

0 dB18.7
dB

18.3
dB

12dB

14.9
dB

12.9
dB

9.8
dB

8.2
dB

6.9
dB

15.3
dB

14.9
dB

13.2
dB

18.9
dB

3.3
dB
Machine mounting with Sylomer®

30 Hz50 HzSylomer® strip bearing

70 Hz

Isotop® SE-2

Compressor operating frequency: 30, 50, 70 Hz

Isotop® DSD

Measuring point: Floor

Isotop® SD

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

MP air handling systems en © Copyright by Getzner Werkstoffe GmbH | 10-2020

Put us to the test!
Every unit is different. And the structure and foundation also differ.
We would be delighted to support you in selecting the right bearing
for your unit or in conducting measurements!