Is there a UK equivalent to Z540.3 calibration?

Z540.3 is a calibration standard utilised by companies operating in the US region that specialise in precision engineering. It is one of a range of globally recognised standards for compliance and testing laboratories, including the gold standard of ISO 17025. Each suits a different type or specialisation of engineering whilst following the standards established by 17025. For precision engineering, Z540.3 has been adopted by NASA and a range of companies for the importance it places on measurement uncertainty. But is there a UK equivalent to the Z540.3 calibration standard?

What is Z540.3 calibration?

Z540.3 is a globally recognised calibration standard for companies operating in the US region, established by both the American National Standards Institute (ANSI) and National Conference of Standards Laboratories (NCSL). It is a standard for measurement and test equipment in laboratories, and was adopted in August 2006 to avoid overlap and confusion with ISO 17025 standards in regards to calibration laboratories. As mentioned in the Z540.3 handbook, its objective is to, “establish the technical requirements for the calibration of measuring and test equipment.”

What is significant about Z540.3?

A number of precision engineering bodies have adopted Z540.3 as their preferred calibration standard, NASA being one of them. This is due to its improved detail and additional requirements when compared to ISO 17025 in the following areas: 

• Calibration intervals & measurement reliability
• Calibration & measurement assurance procedures
• Tolerance-type calibrations
• Measurement risk and test uncertainty ratio (TUR) use
• Measurement uncertainty procedure
• Non-laboratory type calibration services

One aspect of Z540.3 that separates it from ISO 17025 standards is in regards to its threshold of the probability of false acceptance (PFA). The handbook states under section 5.3; “the probability that incorrect acceptance decisions will result from calibration tests shall not exceed 2% and shall be documented.” In comparison, ISO 17025 requires companies to identify contributions and evaluate measurement uncertainty, but does not include a PFA threshold. That said, most calibration labs will work within a required PFA threshold if requested. 

Measurement uncertainty is an important factor to assess the risk and reliability of sensitive and precise equipment. No measurement is 100% accurate, and there will always be uncertainties that come into effect during the testing process. This becomes increasingly important in precision engineering, as the window for uncertainty becomes significantly smaller to ensure performance and safety. This is why Z540.3 is adopted by companies or agencies, such as NASA, as it limits the PFA to 2% to ensure safety and mission success. 

UKAS in comparison to Z540.3

UKAS is a UK government-approved body that specialises in certification, testing, inspection, and calibration services. Similarly to Z540.3, UKAS is a UK regional compliance standard that is globally recognised for the accurate calibration of laboratory equipment and apparatus. In regards to measurement uncertainty,  LAB 12 UKAS standards state that, “unless otherwise specified, the result of the measurement should be reported, together with the expanded uncertainty appropriate to the 95% level of coverage.”

So, if otherwise specified, UKAS calibration requires a 5% PFA compared to the 2% of Z540.3. With a difference of only 3%, UKAS calibration also demonstrates a focus on precision engineering and provides designers with accreditation that is globally acknowledged for it. Where Z540.3 may be better for agencies that operate on the precipice of perfection like NASA, UKAS accreditation still shows a commitment to accurate testing equipment that takes all factors into account (within 5%). 

Ensure precision via UKAS calibration

It is clear that both Z540.3 and UKAS hold precision and tight design tolerances as a priority. At DM Systems & Test, we share the same opinion on precision with numerous UKAS accreditation calibration procedures. We are capable of offering PFA within 2% where required for mechanical and electrical equipment in a range of Industries, from defence and aerospace, to pharmaceutical. We also have ISO-9001 certification, which complements the UKAS calibration services on offer and demonstrates our commitment to quality management.

For more information on our UKAS accreditation, or to find out which of our calibration services are UKAS accredited, get in touch. We have a team of experts who are available to advise and recommend which level of calibration is most suitable for your application or industry sector.