Existing NIST Class F calibration weights in the field will be considered grandfathered in and may continue to be used for legal metrology use as long as they meet NIST Handbook 105-1 (1990) requirements. Although the new revision does supersede the 1990 version, it makes clear that existing Class F weights may continue to be used.

This change is taking place to accommodate for the increasing accuracy of weighing devices used for legal metrology. Class F weights are no longer sufficient for the calibration, inspection, or sealing of weighing devices used for the jewelry, cannabis and pharmaceutical industries.

Existing NIST Class F calibration weights may be reclassified to one of the new specifications if all specifications and tolerances fully comply with the alternative standard. However, the NIST Office of Weights and Measures strongly recommends that you do not reclassify existing Class F weights due to the difficulty of performing compliance evaluation.

At Rice Lake Weighing Systems, our metrology labs are here to help guide customers in selecting the right calibration weight for each application. For more information about Rice Lake’s metrology labs and services, visit www.ricelake.com/calibration.