Calibration of Sound Level Meters (Germany)

The calibration is the legally prescribed test of a measuring device for compliance with the underlying legal calibration regulations, in particular the calibration error limits. A verification is a legally prescribed calibration that can be traced back to national standards.

Validity and labeling

During the calibration, the device is marked as calibrated by seals and secured against unauthorized access. It may not be opened or otherwise changed during the two-year period of validity. In addition, a calibration label with the data of the device (including the software version and accessories used) is attached.

The calibration becomes invalid if the statutory re-calibration period has expired, one of the security or calibration stamps is damaged or removed, the measuring device does not correspond to the information on the type plate or the measuring device does not correspond to the type approval.

It is advisable to have older devices checked by the supplier before each calibration and, if necessary, adjusted in order to save time and costs for unsuccessful calibration attempts.

What is legal for trade?

According to the Verification Act in conjunction with the Verification Ordinance, sound level measuring devices must be calibrated if they are used in the field of occupational safety or environmental protection to carry out public monitoring tasks, to provide reports for public prosecutor or judicial proceedings, arbitration proceedings or for other official purposes or to provide arbitration reports.

Further details are regulated in Annex 21 to the Calibration Ordinance.

What can be calibrated?

As a rule, a prerequisite is a type test and calibration approval for the relevant sound level meter type by the Physikalisch Technische Bundesanstalt (PTB) in accordance with Annex 21 of the Calibration Ordinance.

The conformity with the requirements of the standards valid at the time of the test is tested and confirmed. These can be, for example, earlier standards such as DIN 45657, DIN EN 60 651 and DIN EN 60 804 or the currently valid DIN EN 61672. Sound level meters that were approved for calibration according to previously valid regulations and have already been calibrated once (initial calibration) can still be recalibrated as long as there has been no interruption of the calibration.

What is being checked?

The calibration includes, an acoustic test of the display under reference conditions and the frequency response in the anechoic room, an electrical test of the frequency weighting(s), the RMS value formation, time weighting(s), scale division, range switch levels, and the inherent noise and the control limits.

In the type test (PTB) (requirement for the calibration of devices), device-typical properties - such as directional characteristics, microphones and environmental influences (temperature, pressure, humidity, vibrations, electrical and magnetic fields) - are examined on five specimens of a type.

New software versions for the sound level meters are presented by the manufacturers to the PTB for verification and may only be installed and used after a new calibration for measurements that are subject to verification.

What should I do?

If your device is being calibrated for the first time, the process must be carried out by the manufacturer of the device using the so-called conformity assessment according to MessEG.

If you want to give a device for recalibration, please contact one of the following calibration offices directly to make an appointment:

Berlin Offices:

State Office for Metrology and Calibration
Lentzeallee 100
14195 Berlin
Tel .: (030) 90 259 617
Fax: (030) 90 259 619
Email: State Office for Metrology and Calibration 

Munich Offices:

LMG Bavarian State Office for Weights and Measures
Eichamt Munich-Traunstein
Franz-Wardrobe-Strasse 11
80638 Munich
Tel .: (089) 17 901 240
Fax: (089) 17 901 233
Email: LMG Bavarian State Office

 

The following are to be sent:

• The necessary acoustic accessories
• An informal test order including a list of accessories
• A device manual (German, possibly with supplements)
• Fresh batteries in the device.

Special tests

Sound level meters that are not (yet) approved can, under certain conditions, be presented to the PTB for individual or special tests. The scope of the test and costs roughly correspond to a calibration, but it is only certified to a limited extent that the device “in the tested properties” meets the requirements. In addition, certain public and trade association measuring centers have set up their own calibration laboratories for their devices, which are comparable to the calibration offices in terms of equipment and testing.

Our services team is always happy to answer any questions you may have. Get in touch with your local B&K Sales represensatitive to find out more.