Periodic testing in a NATA accredited calibration laboratory determines whether your sound level instruments meet the stringent requirements of the applicable Australian and international standards for those instruments, as well as the manufacturer’s specifications, ensuring accurate, reliable operation and traceability. Such periodic testing is not only good measurement practice but also a legal requirement under most authorities, including the WA Department of Environment Regulation, the WA Department of Commerce’s Worksafe Division, the Resources Safety division of the Department of Mines & Petroleum, NOPSEMA, WorkCover WA and many others across Australia.
Whilst a simple field calibration is also required for practical and legal reasons each time a sound level meter or dosimeter is used (with the aid of a Brüel & Kjær 4231 Acoustic Calibrator for example – click here for more information), this field calibration is simple in scope, usually testing the response of the sound level meter to just one sound pressure level (SPL) at one frequency, and reading only one parameter.
A comprehensive accredited calibration in a NATA-accredited facility, by contrast, assesses the condition of the instrument under a wide range of operating conditions and tests the limits of the meter across its full range of settings. During an accredited calibration of a sound level meter or dose meter we check*:
- Absolute sensitivity;
- Overall frequency response (both acoustically and electrically);
- The accuracy of all the frequency weighting curves;
- Accuracy of the r.m.s. detector in fast, slow and impulse modes;
- The peak detector’s capabilities;
- Level linearity of the display;
- Overshoot of the display;
- Accuracy of the attenuators;
- Averaging accuracy of both steady-state and intermittent signals;
- Noise floor for all frequency weightings;
- Operation of the overload indicators;
- Octave and one-third octave band filter accuracy;
- AC signal output amplitude.
Not all tests are applicable to all instruments, and the list is not exhaustive.
These very detailed tests, typically conducted every 24 months in WA, complement the simple field calibrations carried out by the instrument user and ensure compliance with regulations, conformance to manufacturers’ specifications, and confidence to the end user.
For further details of our calibration services please contact NVMS, and for more information on NATA accreditation visit NATA’s website at www.nata.asn.au.
For guidance on calibration intervals please contact your workplace authority or environmental department, or contact NVMS for additional assistance.