In our last article, we discussed if we need calibration. Here, we’ll discuss how an accredited calibration differs from a NIST traceable calibration.

Firstly, what is NIST? NIST stands for the National Institute of Standards and Technology. This body was founded in 1901 and is considered a non-regulatory federal agency under the U. S. Department of Commerce. Per NIST’s website, its mission is “to promote U. S. innovation and industrial competitiveness by advancing measurement science, standards, and technology in ways that enhance economic security and improve our quality of life.”1

So how does this relate to the calibration services you receive? A NIST traceable calibration only ensures that the reported results are determined using an unbreakable chain of standards traceable to NIST, the national standard. There is no third-party oversight evaluating technician competency, availability of proper procedures, or inclusion of TAR (test accuracy ratio) or uncertainty in the measurement process.

Here at F. D. Hurka Metrology, we provide what is referred to as an “accredited” calibration. An accredited calibration not only meets the definition of a NIST traceable calibration but also conforms to ISO/IEC 17025 standards. With accredited calibrations, you get the added assurance of measurement competency from a reputable auditor and agency.  The third-party auditor has observed and validated the accredited calibration lab’s procedures, technicians’ proficiency, and test equipment standards meet the highest standards.

What is ISO/IEC 17025? ISO stands for the International Organization for Standardization and is defined as “an independent, non-governmental international organization with a membership of 166 national standards bodies.” 2 ISO/IEC 17025 specifically “enables laboratories to demonstrate that they operate competently and generate valid results, thereby promoting confidence in their work both nationally and around the world.” 3

Per our accrediting body and ISO/IEC 17025 standards, F. D. Hurka Metrology provides on each certificate of calibration all information addressed in section 7.8.2 and 7.8.4 of the standard: the location of performance of the laboratory activities, identification of the method used, the date(s) of performance of the laboratory activity, the date of issue of the report, the units of measurement, identification of the person(s) authorizing the report, the measurement uncertainty of the measurement, the conditions (e.g. environmental), a statement identifying how the measurements are metrologically traceable, before and after readings, and a statement of conformity with requirements or specifications.

Each of F. D. Hurka Metrology’s technicians are aware of these guidelines set forth, have been fully trained, and are extremely competent in their areas of measurement.

One thing to note, per these standards, an accredited calibration lab cannot dictate the calibration interval or make any recommendation on thereof. For more information on determining calibration intervals, please refer to your facility’s quality policy. Though an accredited calibration lab cannot recommend calibration intervals, we can recommend some things to consider. Your facility and accrediting body, industry, or testing standards may have specific requirements. How frequently is the item used? What is the risk if your test equipment is found out of tolerance? What type of environment is the item stored in? What is the manufacturer’s recommended calibration interval? Are there spot checks performed periodically in between calibrations? There are these and many more factors to take into account. When determining a calibration interval, you may refer to ILAC G24:2007 for further recommendations of factors to consider. 4

For more information on the topics discussed, please visit the links below:

By / Published On: October 19th, 2021 / Categories: Calibration /


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  • F. D. Hurka Metrology
    4731 Stockholm Court
    Charlotte, NC 28273

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  • F. D. Hurka Metrology
    P.O. Box 240695
    Charlotte, NC 28224

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