Are NIST traceability requirements equivalent to UKAS?

When it comes to calibrating mechanical equipment, ensuring it is in line with the standards that are applicable to your industry is vital in ensuring its accuracy. Traceability is a key aspect in mechanical calibration that provides a full paper trail to these standards, leaving you confident that your equipment is compliant and reliable.

Traceability requirements differ depending on the standard. NIST is a US based standards body that has its own variations and requirements in terms of traceability. But what exactly are the requirements NIST has for traceability, and how does it differ to the rules stipulated by UKAS?

What is calibration traceability?

Calibration traceability refers to the unbroken chain of calibrations leading to an initial recording against a national or international standard. This chain includes vital information including dates, locations and persons involved in each calibration, providing a holistic view of an instrument’s history. Additionally, some standards require specific factors such as measurement uncertainty to be recorded alongside these details.

The requirements of calibration traceability are stated in ISO 17025, section 6.5; “the laboratory shall establish and maintain metrological traceability of its measurement results by means of a documented unbroken chain of calibrations, each contributing to the measurement uncertainty, linking them to an appropriate reference.” Complete traceability of instruments provides assurance of their accuracy and compliance, as well as a paper trail to relevant documentation when checks are required.

What are the NIST metrological traceability requirements?

The National Institute of Standards and Technology (NIST) is a US based government agency that provides calibration and measurement standards for advanced technology and services. Their purpose is to promote innovation and industrial competitiveness via advanced measurement science and standards. One of the ways it achieves this is via their metrological traceability standards.

NIST’s metrological traceability is defined as, “property of a measurement result whereby the result can be related to a reference through a documented unbroken chain of calibrations, each contributing to the measurement uncertainty.” This chain of calibrations is traceable to a standard recognized by NIST, and follows the International System of Units (SI). In order to be recognized as traceable to NIST, equipment measurement results must be made by an instrument that is part of an unbroken chain leading to one of these standards.

What are the UKAS traceability requirements?

UKAS traceability and calibration in the mechanical testing of materials refers to an accreditation given to specialised laboratories. UKAS traceability is recognized internationally and performed in line with ISO 17025 standards. It specifically focuses on laboratories and their capabilities to perform traceable calibration.

UKAS calibrations and traceability is performed under very stringent and precise conditions; a device having a 0.5% tolerance is calibrated using a standard having an uncertainty of 0.05%. There may, however, be exceptions to this rule where a factor of 2 or 5 is acceptable. Additionally, there are many factors that must be recorded to ensure a high level of traceability, including environment, equipment, staff, procedures and intervals.

Which traceability is right for you?

Responsibility

A key difference between UKAS and NIST traceability lies with the responsibility of those that are able to perform said calibration. UKAS traceability can only be performed by specified laboratories that have been deemed capable of performing the detailed calibration and documentation required.

NIST, on the other hand, allows organisations to be responsible for the traceability of their own results to national reference standards that are maintained by NIST. This allows companies to reduce the total downtime of their measurement equipment when they may not require the precise laboratory level of traceability.

Accuracy and risk

Alongside the difference of responsibility, the two forms of traceability are also separated by their attention to accuracy and the risk involved. NIST allows traceability with any apparatus that is part of an unbroken chain of measurements. This makes it easier for equipment in low-risk settings to be checked regularly and efficiently.

UKAS traceability has a greater attention to detail and accuracy, making it the better choice for high-risk and critical applications. It also demands extensive documentation to provide visibility of supply chains and variables that are important in high-risk applications. That said, only accredited laboratories can perform said calibration, which can result in greater time periods where equipment is being calibrated. 

UKAS accredited calibration that is completely traceable with DM

Traceability is vital in ensuring that your equipment is accurate and reliable, especially in critical and high-risk applications. Understanding what standard of traceability is applicable for you is important in not only ensuring this accuracy, but potentially minimising the impact calibration will have on your operations. 

At DM systems and test, we provide complete mechanical traceability via our UKAS accredited laboratories. We go the extra mile for our clients, with a complete team of trained and specialised engineers to deliver completely traceable calibration whilst minimising your equipment downtime. To find out more about how our UKAS accredited calibration can help your business, get in touch with our team today.