On-site vs laboratory calibration: choosing the right one
On-site calibration avoids removing equipment and captures the installed system; laboratory calibration offers better sources, lower uncertainty and controlled conditions.
When on-site makes sense
- Fixed monitoring sensors and controller probes, calibrated in place with a portable reference alongside.
- Large numbers of loggers where downtime matters, using a portable bath or dry block.
- Chambers and rooms, where the object is the space itself.
When the laboratory is better
- Reference thermometers and anything needing uncertainty below about 0.05 °C.
- Calibration over wide ranges or at extremes (−80 °C, > 200 °C).
- Instruments whose calibration requires characterised fixed equipment.
The accreditation scope lists on-site capabilities separately; ask which applies to your job and what the certificate will say about environmental conditions.
Frequently asked questions
- Is on-site calibration of a monitoring probe done by comparison in air?
- Often, using a portable reference placed adjacent to the probe in the space, or a small portable source the probe can be inserted into. The method should be stated and its uncertainty is larger than a bath comparison.
References
- [1]ISO/IEC 17025:2017 — General requirements for the competence of testing and calibration laboratories
General technical guidance written against the cited sources. It is not regulatory or legal advice and does not replace the applicable standard, guideline or a qualified reviewer's judgement.
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