An instrument reading is only as trustworthy as its last calibration. When an auditor asks “how do you know this number is right?”, the calibration certificate is the answer.
What calibration actually establishes
Calibration compares your instrument against a reference standard that is itself traceable to a national or international standard. The certificate records the difference (the error) at several points across the measuring range, and the uncertainty of that comparison.
How to read the certificate
- Traceability: which reference standards were used, and their own certificate numbers
- As-found vs as-left: the error before and after any adjustment
- Measurement points: calibration at one point tells you little about the rest of the range
- Uncertainty: usually at 95% confidence (k=2)
- Environmental conditions: temperature and humidity during the calibration
- Due date or interval: when the next calibration is required
Setting the interval
Manufacturers suggest a starting interval (often 12 months). Adjust it based on how the instrument drifts between calibrations, how heavily it is used, and how critical the measurement is.
EnviraH provides traceable calibration and managed calibration schedules for environmental and gas-detection instruments. See the service.
