Sheffield Calibration Services must adhere to the international standard, ISO/IEC 17025:2017 for testing and dimensional laboratories when performing all UKAS Calibrations. The standard has a host of requirements to be fulfilled by the laboratory to ensure the laboratory can garner client confidence, operate competently and ensure the validity of results. Some of those requirements mean the laboratory has rules and policies in place to cover the requirements of the calibration at the contract review stage and they can be viewed below.
We will automatically perform calibrations to the most relevant standard, be it the British standard (if available) or a similar European / international standard. If no standard can be sourced then the manufacturers specification will be sought unless the customer can provide a specification of their own.
If the calibration is performed to a specification then, Clause 7.8.6 of ISO/IEC 17025:2017 requires that when a statement of conformity to a specification or standard is provided, the laboratory shall document the decision rule employed, considering the level of risk associated with the decision rule employed, and apply the decision rule. Furthermore, this decision rule must be agreed with the customer and also reported with the results on the calibration certificate.
With the above in mind the laboratory has chosen to apply the simple acceptance shared risk rule to all calibration certificates to meet the statement of conformity requirement. This rule considers the laboratories uncertainties when applying the measured errors but does not include the uncertainty in the error providing the laboratory can prove their uncertainty to be less than the tolerance applied. The level of risk includes the uncertainty of measurement and is defined as providing a 95% level of confidence in the uncertainty of measurement and has been carried out in accordance with UKAS requirements.
For full details of the rule applied it can be found in clause 8.2.3 of the metrology guide JCGM 106 2012 – the role of measurement uncertainty in conformity assessment.
The laboratory has implemented a policy to cover the requirements of this section. (POL 7.8.6) and this can be viewed on the standards and policy page on this website. The simple acceptance shared risk rule is preferred by the laboratory and is applied unless instructed by the customer at the contract review stage. The level of risk includes the uncertainty of measurement and is defined as providing a 95% level of confidence in the uncertainty of measurement and has been carried out in accordance with UKAS requirements.
To meet the requirements of the Rule and prove the level of risk has been considered and accounted for, the laboratory will require an uncertainty budget for all features measured and reported on a calibration certificate. The Rule will replace our previous method of reporting accuracy statements which did not consider uncertainty values before the implementation of ISO/IEC 17025:2017.
Please feel free to contact the laboratory if you have any concerns regarding the decision rule and how to move forward regarding the application or non-application of the Rule to future calibrations.
All items to be UKAS calibrated must have legible identification, preferably permanent.
If we do receive an Item for calibration without identification then the laboratory will apply non permanent identification for the calibration only and a statement applied to the certificate to read: The serial number has been applied by the laboratory for calibration purposes only.