A New ASTM E617 Standard and What It Means for NIST Handbook 105-1

One of OWM's main responsibilities is to harmonize international and national documentary standards with those used by the U.S. weights and measures community. Therefore, in 2019, OWM worked with the weights and measures community that regularly uses NIST Handbook 105-1 (1990), Specifications and Tolerances for Field Standard Weights to begin phasing out NIST Class F mass standards and utilizing the OIML R 111-1 (2004) aligned specifications and requirements found in ASTM E617, Standard Specification for Laboratory Weights and Precision Mass Standards. The ASTM E617 standard was recently revised in 2023, and this article provides a review of the key updates and what they mean for weights and measures programs that adopt NIST Handbook 105-1 (2019).  

The NIST Handbook 105-1 (2019) discontinued the acceptance of new Class F weights into service for legal metrology applications after January 1, 2020. It directed users to follow the requirements of ASTM E617, Standard Specification for Laboratory Weights and Precision Mass Standards, instead of the 1990 version of NIST Handbook 105-1, which has been withdrawn and exists only as a reference document for the remaining Class F weights. As expressed in a 2019 OWM Technical Article, “NIST Handbook 105-1 REVISED! What Now?”, the ASTM E617 (2018) documentary standard contained inconsistencies, which made its implementation as required by the NIST Handbook 105-1 (2019) a challenge. The 2023 edition of ASTM E617 has corrected most of these inconsistencies and allows users to better implement its requirements.

There were several updates made to the 2023 version of ASTM E617, including to material, with none more important than to the maximum permissible error (MPE) values of the ASTM E617 accuracy classes. In particular, the ASTM Class 6 accuracy class was updated to align with the old NIST Class F MPE values. The result of this modification will allow the conformity assessment of ASTM Class 6 weights to be implemented via a similar process of evaluation as used for Class F weights regarding precision assessments and measurement results ± MPE. Users will now be able to use the ASTM Class 6 accuracy class without needing to substitute in ASTM Class 5 MPE values for small nominals previously not listed in the standard with MPE values. This will simplify the evaluation process for legal metrology laboratories with customers with well-maintained Class F weights put into service prior to January 1, 2020 and ASTM Accuracy Class 6 weights. Users are reminded to not reclassify weights, as stated in NIST Handbook 105-1, unless you are the manufacturer with knowledge of the material used and build of the mass standard. Customers of mass standards should be directed to contact the manufacturer for any questions regarding the accuracy classification of their mass standards. Class F weights should reference NIST Handbook 105-1 (1990) and ASTM Class 6 weights should reference ASTM E617 (2023).

ASTM documentary standards are reviewed at least every 5 years, or as needed based on technical requirements. The ASTM E41 standards committee working group is currently reviewing some lingering and new inconsistencies with the latest ASTM E617 standard. An updated version is expected to be voted on and released in 2025. Interested metrologists are encouraged to become active members of the ASTM E41 committee on Laboratory Apparatus to participate in the development and new release of the standard. For additional questions or concerns, please contact the OWM Laboratory Metrology Program (micheal.hicks [at] nist.gov (micheal[dot]hicks[at]nist[dot]gov) or elizabeth.koncki [at] nist.gov (elizabeth[dot]koncki[at]nist[dot]gov)).