How to judge whether the sound level meter is qualified according to the certificate?
1. The calibration certificate of the sound level meter is useless, and it can only be used normally if a verification certificate is issued and a qualified conclusion and accuracy level are drawn.
The daily verification of sound level meters requires a lot of equipment, such as calibrator, standard condenser microphone, signal generator, measurement amplifier, tone burst signal generator, precision attenuator, voltmeter, sound source, anechoic box (free field), etc. All equipment needs at least 30W or more, and it takes up a lot of space, so there are certain technical requirements; at the same time, there are not many instruments for sound level meter verification, and the standard devices have to be submitted for inspection every year, so it is not cost-effective to establish a complete set of acoustic verification devices. Many provincial metrology institutes have not established sound level meter verification devices, and cannot issue sound level meter verification certificates.
2. Frequently asked questions
① Is the calibration certificate of the sound level meter useful?
The calibration certificate of the sound level meter is useless, and it can only be used normally if a verification certificate is issued and a qualified conclusion and accuracy level are drawn.
The sound level meter is a mandatory verification measuring instrument. If the verification institution issues a calibration certificate or a test report, it means that the performance index of the sound level meter cannot meet the requirements of GB/T 3785-2010 (IEC 61672:2002). According to the verification regulations JJG 188- The 2002 test failed and cannot be used. (Another situation is that the sound level meter itself is qualified, but the Metrology Institute does not have the verification qualification and can only issue a calibration certificate. This certificate is also invalid. Just send the sound level meter to a metrology institute with verification qualification for verification)
② Can the verification items of the sound level meter be freely selected?
No, there are 10 items in the conventional sound level meter verification, and a verification certificate can be issued after all of them meet the requirements, and many of them have not obtained CMC
Or CPA sound level meter, only 2 to 5 items can meet the requirements, and other functions do not or cannot meet the standards. At this time, the Institute of Metrology usually only gives the indicators of passing the inspection, and does not give other indicators. At the same time, it only issues a calibration certificate, pushing all the risks to the enterprise, and charging its own calibration fees. However, when using a sound level meter with only a calibration certificate, the risk is entirely borne by the company. This risk is very high, and there is no need for the company to bear it. It is only necessary to issue a calibration certificate.
③Are international standard sound level meters more advanced?
Yes, instruments with international standards are more advanced. The national standard for sound level meters is GB/T 3785-2010, which is equivalent to the international standard IEC 61672:2002. Although the national standard for sound level meters is a recommended standard, since the sound level meter is a measuring instrument supervised by the state, the manufacturing license CMC must be obtained before production, and the premise of obtaining CMC is to pass the type approval CPA. At present, the type approval of the sound level meter completely adopts the standard of IEC 61672:2002, so the national standard (equivalent to the national standard) of the sound level meter is actually mandatory.
④Whether the performance index and accuracy level of the sound level meter can be written by the company itself?
Can't. Instruments such as sound level meters and vibration meters are produced under national supervision, and their important performance indicators and accuracy levels are given by the national type approval certificate. It is not written casually by the company itself. At the same time, the type approval certificate must be given in the product specification of the enterprise.
There are many sound level meters that do not meet the standards and pretend to be imported or other instruments. They can only issue calibration certificates, and they dare not even give the accuracy level. They are 100% unqualified. Production and sales are illegal, and there are huge risks for users, so please be careful.
