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Can an auditor challenge the metrological traceability aspects of a calibration document with the Cofrac logo?


Recap of a concrete example submitted to the CFM.

« During an audit, I was asked to prove that my measurement standards had been verified using valid appliances. The certificate supplied by the laboratory included the Cofrac calibration logo and mentioned the appliance used to check my keys and the verification reference.

The auditor claimed that the period of validity of the appliance could well have expired or that the appliance was not part of Cofrac’s scope of accreditation assigned to this laboratory (he had already come across similar cases). He asked me for the verification certificate of the appliance and the scope of accreditation assigned by Cofrac.

The Cofrac-accredited laboratory will not give me these documents, claiming that the auditor is overstepping his rights and that the Cofrac logo is sufficient. »

We regularly receive questions of this type, but it is quite clear that, if your instruments have been calibrated by a laboratory accredited by Cofrac, and if this laboratory issued a calibration certificate with the Cofrac logo, then the auditor cannot go any further along the chain of metrological traceability.

The laboratory was perfectly right. The use of Cofrac’s logo (or the logo of an accrediting agency that has signed the ILAC recognition agreement) is sufficient in order to certify traceability in the international system of units. You can check the fields of accreditation on the Cofrac site ( by searching for your service provider’s certificate using the accreditation number on the calibration certificate. You are entitled to do this in the course of an audit, if the auditor contests the reference of the certificate.

If the auditor is still not satisfied with this answer, then contact Cofrac and explain just what the auditor wants. You can also send a complaint to your certifying agency in accordance with the ISO/IEC 17021 accreditation requirements, then send a copy to Cofrac if you do not receive an answer.