Measuring instruments for pressure and temperature are used in almost all regions of industrial manufacturing. Because of continuous mechanical, chemical and thermal loading, these instruments age and may therefore not guarantee the correctness of the measured values over the course of time. Through timely calibration, however, the alteration of the measured value can be determined.
In Hero of calibration, the displayed value of the measuring instrument is compared with the measuring consequence of a different measuring device that is known 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 (using the exemplory case of Germany) depicts the traceability of an inspection equipment in a company up to a national standard at the PTB (German national metrology institute).
So as to ensure traceability used, the following points should be observed, amongst others:
The chain of comparison must not be interrupted.
The measurement uncertainty should be known in each stage of the calibration chain in order that the total measurement uncertainty can be calculated. As a rule, a superordinate measuring instrument should have a measurement accuracy 3 to 4 times higher.
Each step in the calibration chain should be documented, including the measurement results.
All bodies conducting a stage in the chain must prove their competence by way of accreditation.
Calibrations should be repeated at appropriate intervals. The periods depend on the demanded measurement accuracy and the technical requirements
Note
The WIKA calibration laboratory is accredited by the German Accreditation Body (Deutsche Akkreditierungsstelle ? DAkkS) relative to DIN EN ISO / IEC 17025 for the measurands temperature, pressure, DC current, DC voltage and DC resistance. Hazardous on our calibration laboratory or an on-site calibration with the WIKA calibration van are available on the WIKA website. When you are thinking about our services, please feel free to contact us via e-mail.
Find out about the differences between factory calibration and traceable calibration in the following video: