{"id":159108,"date":"2021-07-21T14:26:52","date_gmt":"2021-07-21T12:26:52","guid":{"rendered":"https:\/\/bandelin.com\/?post_type=docs&p=159108"},"modified":"2025-08-26T08:31:25","modified_gmt":"2025-08-26T06:31:25","password":"","slug":"health-hazards","status":"publish","type":"docs","link":"https:\/\/bandelin.com\/en\/docs\/wissen\/gesundheitsgefaehrdung\/","title":{"rendered":"Health hazard"},"content":{"rendered":"

Ultrasound and health hazards<\/strong><\/h2>\n\n\n\n

Noise<\/strong><\/p>\n\n\n\n

Ultrasound produces inaudible and audible noises. Typical is the hissing working noise that occurs with liquids. Possible health effects depending on the intensity can be:
subjective - pain, dizziness and
objective - impairment of hearing.<\/p>\n\n\n\n

For the practical assessment of noise situations, sound pressure level measurement with weighting is used. Instead of the usual A-weighting, which produces considerable measurement errors in the presence of ultrasound, the AU-weighting is used for ultrasound. This takes into account the sensitivity of the human ear to airborne sound at ultrasonic frequencies.<\/p>\n\n\n\n

\"\"<\/a><\/figure>\n\n\n\n

Explanations on the evaluation:<\/strong><\/em>
Sound level meters using the A-weighting curve are unsuitable for noise measurement in the presence of ultrasound, as the built-in filters are only standardised for sound pressure levels up to a frequency of 12 kHz. Higher ultrasonic operating frequencies of 20 kHz and above can therefore lead to incorrect, significantly higher or even lower measurement results. For this purpose, the IEC has adopted an extension of the A-weighting curve above 12 kHz - the filter curve U - as an international standard.
Combined with the A-assessment, the so-called AU-assessment was introduced, defined in DIN EN 61012.\/1<\/sup>. The AU level assessment is based on extensive measurements of hearing threshold curves with 8 kHz third-octave centre frequencies and thus enables a proper broadband assessment of the sound level.<\/p>\n\n\n\n

For a preliminary assessment of the noise situation, e.g. a sound level measurement with AU assessment in the direct sound field above the ultrasonic source is useful.
Based on the VDI guideline VDI 3766\/2<\/sup>BANDELIN has defined the measuring set-up for ultrasonic baths shown above (homogenisers similar) for person-related simulation and reproducibility of the measurements. Two measurements are carried out:
I. at a distance of 1 m above the surface of the bath; the microphone axis is directed towards the sound source.
II. with equal distance; microphone axis at an angle of 45\u00b0.<\/p>\n\n\n\n

In our production facilities, AU-weighted sound pressure levels are measured for the ultrasonic baths with lid and basket.
The sound pressure level for all baths is
L\/pAU(t)<\/sub> < 80 dB
and is thus below the recommended guideline value of the VDI 3766 guideline.
The noise level is strongly dependent on the construction, the installation situation and the use. Therefore, no general statement can be made about the sound pressure level at the installation site.<\/p>\n\n\n\n

An excessively high sound pressure level can have various causes, most of which can be easily remedied:
- Changing the position of the sonication object, never place objects on the floor of the tub
(baths).
- Changing the immersion depth of the sound reinforcement object (baths) or the
Sonotrode (homogenisers)
- Changing the filling level of the bath liquid, operation with lid (tub baths).
In general, it is recommended to wear suitable hearing protection or to use appropriate noise protection boxes when working continuously within a radius of 2 m:
- For ultrasonic baths, e.g. under:
https:\/\/www.sonation.com<\/a>\/
- For ultrasonic homogenisers, e.g. under:
https:\/\/bandelin.com<\/a>\/
If there is no improvement, please contact the manufacturer.
Notes:
(1) Basic provisions for the protection of employees from hazards due to noise and vibrations are regulated in the Noise and Vibration Occupational Health and Safety Ordinance (L\u00e4rm- und Vibrations-Arbeitsschutzverordnung - ArbSchV) and must be observed accordingly.
2. the DIN 45645-2 standard\/3<\/sup> is not suitable for an assessment of ultrasound exposure in the workplace.<\/p>\n\n\n

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Highly effective noise reduction with the LS 40 noise protection box for BANDELIN SONOPULS homogenisers<\/div><\/div>
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