As per Clause 6.4.6 of ISO 17025:2017:
6.4.6 Measuring equipment shall be calibrated when:
- the measurement accuracy or measurement uncertainty affects the validity of the reported results, and/or
- calibration of the equipment is required to establish the metrological traceability of the reported results.
It follows that as long as the above criteria are applicable, a laboratory will have to calibrate the measuring equipment. The laboratory may opt to perform the above mentioned calibration(s) in-house. The laboratory would then need to comply to the requirements of ISO 17025:2017, for these in-house calibrations.
Do the accreditation bodies agree that when a laboratory performs in-house calibrations for such measurements, then the laboratory will also need to comply with the below requirement in relation to participation in applicable interlaboratory comparisons?
7.7.2 The laboratory shall monitor its performance by comparison with results of other laboratories, where available and appropriate. This monitoring shall be planned and reviewed and shall include, but not be limited to, either or both of the following:
a) participation in proficiency testing;
b) participation in interlaboratory comparisons other than proficiency testing.
7.7.3 Data from monitoring activities shall be analysed, used to control and, if applicable, improve the laboratory’s activities. If the results of the analysis of data from monitoring activities are found to be outside pre-defined criteria, appropriate action shall be taken to prevent incorrect results from being reported.
ISO/IEC 17025:2017 cl. 7.7.2 requires laboratories to monitor the performances of their activities by comparing their results with other laboratories, where available and appropriate. This is true for all lab activities, including internal calibrations.
The laboratory shall plan its participation in PTs using a risk-based approach (ISO/IEC 17025:2017 cl. 8.5) taking into account also internal calibration, and ILAC P9 and EA-4/18 do not give additional rules concerning in-house calibration.
As a consequence the appropriate approach of the laboratory to PT for internal calibration will depend on the specific context and activity performed and on the outcome of the risk assessment performed by the laboratory.
If there is a calibration PT not covering the calibration of auxiliary measurands (done as internal calibration, not offered to customers as accredited calibration) then an additional PT should be planned for this particular internal calibration on a risk-based approach.
It is also acknowledged that there are lab activities where participation in PT for in-house calibration would be critical or would be the unique available choice, i.e. where calibration is the dominant factor for bias’s result.
Furthermore, the choice of participating in PT for internal calibration should not be based merely only on economic reasons and shall ensure that the customer requirements and needs are met.
In any case all the 17025 requirements shall be applied in same way for internal or external calibration.
The standard requires participation in PTs “where appropriate” (cl. 7.7.2) that is taken to be when it is suitable, a good choice amongst others, effective, good value, representative, meaningful etc.