When not ISO 17025 Accredited, Calibration Certificates can be difficult to check
And sometimes it's as if the Calibration Laboratory were trying to confuse you!
ISO 17025:2017, which sets out general requirements for the competence of testing and calibration laboratories, has in recent years become the ‘new normal’ for laboratories offering reliable testing services and dependable calibration certificates (as well as verification certificates. In doing so it has clarified the ‘ground rules’ as to what constitutes a credible Calibration Certificate.
Too often in the past, a Calibration Certificate has been viewed as just another record to be retained. The question of its validity in underwriting the dependability of measurements taken with the calibrated device was rarely asked. However, this becomes a real issue if the Certificate you present is challenged by a customer or by a barrister in a Court of Law, and it ‘doesn’t stand up’. It will likely cost you business and may cost you a lot of money. What then constitutes a genuine Calibration Certificate?
How to Know if Your Laboratory's Calibration Certificate is Legit
To verify if your laboratory's calibration certificate is legitimate, make sure you follow the guidelines below.
- Look for traceability. Traceability (or more precisely, measurement traceability) is fundamental to the credibility of a Calibration Certificate. It is used to refer to an unbroken chain of comparisons relating an instrument's measurements to a known standard. Calibration to a traceable standard can be used to determine an instrument's bias, precision, and accuracy.
- Assess the Uncertainty of Measurement. The Uncertainty of Measurement relates to the quality or confidence one can place on measurement made. This tells us something about the quality of a measurement. It is the doubt that exists about the result of any measurement. For every measurement - even the most careful - there is always a margin of doubt. Therefore, two numbers are really needed to quantify uncertainty. One is the width of the margin or interval. The other is a confidence level. For example, a metre stick might be calibrated as ‘1000 +/- 1 mm (the margin) with coverage factor k = 2’ (the confidence level, which here corresponds to 95%).
- Find out the method used. Method, in this context, is used to refer to the measurement procedure. It is based on the method that the confidence level has been established. This is usually a national or international standard method but may also be a validated laboratory-developed method.
The role of the Verification Certificate
These are often presented under the title ‘Calibration Certificate’ and yet cannot meet all of the three basic requirements of a Calibration Certificate (traceability, uncertainty of measurement, and method).
This misnaming only obscures the very important function of a Verification Certificate, which is to provide objective evidence that a given item fulfils specified requirements. And our experience with our ISO 17025 Courses is that our Learners have rarely seen the term Verification Certificate.
Note: The title 'Test Certificate' is an acceptable alternative to 'Verification Certificate'.
The item in question might be a process, measurement procedure, material, compound, or measuring system. Examples include …
- Confirmation that performance properties or legal requirements of a measuring system are achieved.
- Confirmation that pipettes and burettes used for capacity measurements meet legally specified tolerances.
- Confirmation that a Reference Oil meets a standardized specification.
- Confirmation that commercial ceramic oven has been serviced and restored to the manufacturer’s original specified performance.
But why misname them? Most likely it’s to justify the fees charged by inferring a higher grade of service.
And then there’s the nonsensical "Calibration Certificate!"
These are those so-called Calibration Certificates that include some or all of the following …
- The certificate does not contain an uncertainty of measurement statement (the most common deficiency)
- The certificate contains multiple logos, most of which refer to obscure trade associations or similar. There is only one type of logo that counts when it comes to checking the validity of your laboratory's accreditation. That is for your ISO 17025 Accreditation to be provided by an Accreditation Body that is a member of the International Laboratory Accreditation Cooperation or ILAC.
- The certificate contains multiple pages of tabulated figures most of which are largely irrelevant.
- The certificate does not contain the printed name of the technician or analyst who carried out the work. It usually only contains an illegible signature.
- You get separately supplied copies of genuine calibration certificates for the devices used in carrying out the work. Usually not referenced on the Calibration Certificate itself.
- You get good work from the analyst/technician and an acceptable method was used, but the certificate does not record the necessary information for it to be dependable.
- There is a spurious reference to ISO 9001 Certification (and often with a deficient logo) suggesting relevance to the Calibration Certificate itself.
There is, however, one thing questionable ISO 17025 certificates all have in common, namely a failure to meet all three basic requirements of a dependable Calibration Certificate (see above).
So, be sure you don’t get fooled by a nonsensical certificate
It really is quite easy. Just focus on the three basics and ignore all the distractions. If all three basic requirements are not clearly met, the Calibration Certificate is not dependable and you should reject it, ask for a proper replacement or, failing that, get your money back.
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deGRANDSON Global is an ISO Certified Educational Organization
In October 2021 we secured certification to three education-related ISO Standards. We now have a university-grade management system in place conforming to the requirements of …
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