Measuring instruments for pressure and temperature are used in almost all areas of industrial manufacturing. As a result of continuous mechanical, chemical and thermal loading, these instruments age and will 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.
Along the way of calibration, the displayed value of the measuring instrument is weighed against the measuring consequence of another measuring device that 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 a nutshell, in order to compare measuring results, they must be ?traceable? to a national or international standard with a chain of comparative measurements. Corrupting shown in the picture (utilizing the example of Germany) depicts the traceability of an inspection equipment in a company up to national standard at the PTB (German national metrology institute).
So as to ensure traceability used, the following points should be observed, among others:
The chain of comparison must not be interrupted.
The measurement uncertainty must be known in each stage of the calibration chain so that the total measurement uncertainty can be calculated. Generally, a superordinate measuring instrument must have a measurement accuracy three to four times higher.
Each part of the calibration chain should be documented, like 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. Further information on our calibration laboratory or an on-site calibration with the WIKA calibration van are available on the WIKA website. Should you be thinking about our services, please feel free to contact us via e-mail.
Find out more on the differences between factory calibration and traceable calibration in the next video: