Calibration and Traceability

01.

For the measurement of a reference standard to be accepted, it must be traceable. In practice you probably have seen statements like “Directly Traceable to NIST”. But what does it mean? First let’s look at the definition for metrological traceability: Property of a measurement result whereby the result can be related to a reference through a documented unbroken chain of calibrations, each contributing to the measurement uncertainty. ​

Traceability is not only desirable but a requirement per ISO/QS 9000 quality systems. Calibration and traceability requirements are often interpreted as only requiring a calibration sticker on the measuring equipment and the reference to a NIST test number on a calibration certificate. Of importance to note is that traceability is the property of the result of the measurement, not of a standard, calibration report or laboratory. Only the measurement result for a standard can be traceable, and only if the standard was appropriately maintained, used, and documented.​