Measuring instruments for pressure and temperature are used in almost all regions of industrial manufacturing. Due to continuous mechanical, chemical and thermal loading, these instruments age and may therefore not guarantee the correctness of the measured values during the period of time. Through timely calibration, however, the alteration of the measured value could be determined.
Along the way of calibration, the displayed value of the measuring instrument is compared with the measuring result of another measuring device which is recognized to function correctly and accurately and which itself has been designed to coincide directly or indirectly with a national (or international) reference instrument. In short, in order to compare measuring results, they need to be ?traceable? to a national or international standard via a chain of comparative measurements. The calibration hierarchy shown in the picture (utilizing the exemplory case of Germany) depicts the traceability of an inspection equipment in a company up to national standard at the PTB (German national metrology institute).
So that you can ensure traceability used, the following points must be observed, amongst others:
The chain of comparison should not be interrupted.
The measurement uncertainty must be known in each stage of the calibration chain so the total measurement uncertainty can be calculated. Generally, a superordinate measuring instrument must have a measurement accuracy 3 to 4 times higher.
Defying of the calibration chain must be documented, including the measurement results.
All bodies conducting a stage in the chain must prove their competence through accreditation.
Calibrations must be repeated at appropriate intervals. Rested be determined by the demanded measurement accuracy and the technical requirements
Note
The WIKA calibration laboratory is accredited by the German Accreditation Body (Deutsche Akkreditierungsstelle ? DAkkS) in accordance with DIN EN ISO / IEC 17025 for the measurands temperature, pressure, DC current, DC voltage and DC resistance. More info on our calibration laboratory or an on-site calibration with the WIKA calibration van are available on the WIKA website. For anyone who is thinking about our services, please feel free to contact us via e-mail.
Learn more about the differences between factory calibration and traceable calibration in the next video: