General information regarding Calibration of measuring equipment
Often in daily use, no clear and consequent distinction is made between the terms calibrated and adjusted.
Calibration means to document the deviation of the measured value of a measuring device from a traceable, highly accurate standardized calibration standard. Here under specific reference conditions and reproducible measurement methods, the measured value of a measuring instrument is compared with the known value of a calibration standard.
Calibration does not mean that any interference in the measuring equipment is made, the measuring equipment remains unchanged.
Adjustment means setting or adjusting a measuring device to eliminate systematic measurement differences. Here under specified reference conditions, the measured value of a measuring instrument is adjusted to the value of a known calibration standard.
Adjustment is always an intervention that changes the measurement instrument permanently.
Traceability of calibration means the calibration chain is reproducibly documented from the measurement instrument to the national calibration standard of measure.
Traceability of measurement results is ensured by the metrological infrastructure of a country.
Why calibration of measuring equipment is required?
The standard for quality management systems DIN EN ISO 9001: 2008 Section 7.6 specifies essential requirements for monitoring of measuring instruments, as far as these are used to ensure valid results, and thus constant product quality. At specified time intervals, measuring instruments must be made traceable to national calibration standards and if needed re-calibrated and labeled so that the calibration status is recognized. If during calibration it is determined, that the measuring instrument does not meet the requirements, the company must assess the validity of the previous measuring results and take appropriate measures with respect to the measuring instrument and all products affected.
Periodic calibration thus is ensuring the product or service quality on the basis of internationally comparable measurement results. This creates legal certainty with regard to product liability and for acceptance tests and assessments.
For recalibration of measuring equipment, which in turn serves as standard - for monitoring of other measuring and testing, to ensure the traceability to national standards, a DAkkS calibration is recommended.
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