QualitySIRC Laboratory2 min read
Most calibration certificates get filed without being read. They arrive, somebody checks there is a tick in the pass box, and the folder goes back on the shelf until the auditor asks for it. That is a shame, because the certificate is the only evidence you have that your measurements mean anything — and a surprising number of them do not say what people assume they say.
The four things worth checking
- As-found and as-left values. Both, as numbers, not as a verdict. If only as-left appears, you cannot tell whether the instrument was drifting.
- Measurement uncertainty. A stated figure, per point. "Within manufacturer's specification" is not an uncertainty.
- Traceability. Which reference standard was used, and its own certificate number. The chain has to be unbroken all the way to a national standard.
