Metrological traceability in ISO/IEC 17025 (clause 6.5)
Results must be traceable to the SI through calibration by a competent laboratory, certified values of certified reference materials, or direct realisation of SI units.
Clause 6.5 requires the laboratory to establish and maintain metrological traceability of its measurement results by means of a documented unbroken chain of calibrations, each contributing to the measurement uncertainty, linking them to an appropriate reference.
Accepted routes to the SI
- Calibration provided by a competent laboratory — in practice, one accredited under the ILAC arrangement or an NMI.
- Certified values of certified reference materials from a competent producer.
- Direct realisation of SI units ensured by comparison with national or international standards.
ILAC-P10 sets the accreditation-body policy that gives these routes teeth: a certificate from a non-accredited laboratory generally cannot be used to demonstrate traceability without the laboratory itself demonstrating that provider's competence.
Frequently asked questions
- Is a manufacturer's factory calibration acceptable for traceability?
- Only if the manufacturer's laboratory is accredited for that calibration, or if you can demonstrate its competence yourself — which is rarely practical.
References
- [1]ISO/IEC 17025:2017 — General requirements for the competence of testing and calibration laboratories
- [2]ILAC-P10: ILAC Policy on Metrological Traceability of Measurement Results
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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