When choosing the service of a 3rd party lab, make sure that it is an accredited lab. When a lab is accredited, it means that the accreditation bodies have assessed the competency of the lab in terms of its procedure, personnel, equipment, and environmental conditions as per the requirements of a standard like ISO 17025:2017..

This will ensure that the calibration performed on our calibrators is link or traceable to the national standard up to the SI units.

But in order to ensure that our reference standard is traceable, it should have a calibration certificate with the below details.

These are also the Evidence of Traceability in A Calibration Certificate

1. The logo of the accreditation body is evident.

2. Estimated uncertainty results are displayed.

3. It has the details of the reference standard used in calibration

4. It has the details of the calibration procedure used.

5. A recorded environmental conditions 

6.A statement that it is “Traceable to International Standards (SI units)”

These traceability evidence in the calibration certificate are the documented traceability chain, this is why it is very important to ensure its completeness when receiving or generating a calibration report

How to Ensure Lab Has Traceability if it is not Accredited- Traceability Audit Requirements

There are times where there are no available calibration labs that can perform the calibration of our instruments or standards. This is not a problem as long as we can verify through audit below traceability requirements.

These traceability requirements can also be used as evidence to satisfy auditors during scheduled audits if we want to establish our In-House calibration. 

These are:

1. The Measurement Uncertainty results

2. Documentation in establishing a traceable reference standard used in calibration (calibration certificates)

3. A recorded environmental conditions 

4. Documented Personnel training or competency

5. Documented Calibration procedures

6. Documented validation and/or verification of methods

7. Recorded Audits of calibration provider

8. Documentation for assuring the validity of results (intermediate checks or calibration interval)

When Does Traceability Become Invalid?

Traceability in calibration is not permanent. This is the reason why we have to implement a quality assurance program in order to maintain and ensure traceability.

Below are some reasons where traceability can be rejected or invalidated:

1. When the calibration date is Overdue

2. The reference standard used is not Traceable to SI (reference standard used is not linked to SI or any traceability chain)

3. Void Seal has tampered 

4. Details of Instruments does not match what is written in its calibration certificate

5. When a reported result has insufficient information (see the Evidence of Traceability in A Calibration Certificate above)

6. Measurement uncertainty is too large. How good is an uncertainty result if it resulted in an out of specification once added to the measured value? – Learn more about this in this post>> Decision Rule

Conclusion:

Metrological Traceability is one of the core requirements in calibration that needs to be fully understood and integrated into our measurement process. Without traceability, the calibration performed will not be valid.

Acquiring and establishing traceability based on the traceability chain does not end when we receive our instrument from a trusted provider, but just the beginning of a more challenging task.

Understanding the principles and requirements of traceability based on ISO 17025 will help us maintain metrological traceability in our calibration. These are the quality assurance programs that will help us to have continued confidence and validity of our measured value.