The National Institute of Standards and Technology (NIST) updated Handbook 105-1 in 2019 with ramifications for NIST Class F weights beginning January 1st, 2020. Handbook 105-1 sets the specifications and tolerances for reference standards and field standard weights and measures. With historically few revisions, Handbook 105-1 was last revised in 1990.

What's changing?

The 2019 revision addresses the issues arising from the increased use of Class I and Class II weighing devices in commercial applications. The 1990 version of Handbook 105-1 required tolerances of standards to be approximately 0.01% of nominal value. This tolerance is no longer adequate for all commercial systems, which require stricter accuracy like those used for jewelry and cannabis sales. The new recommendation from Handbook 105-1 is to choose from a much broader choice of standards using ASTM E617 and OIML R111.

Can I use our existing NIST Class F standards?

NIST Class F field standards will not be available for legal metrology use after January 1st, 2020. Any NIST Class F weights placed into service before this date will still be usable for legal metrology applications and will not require removal from service.

Can I reclassify our existing NIST Class F weights?

Although reclassifying existing NIST Class F weights to one of the new specifications, if all requirements and tolerances fully comply with the alternative standard, is possible, the NIST strongly advises against reclassification. The known differences between the documentary standards and the ability to evaluate the compliance of the physical characteristics are the main factors in NIST's recommendation. If you would still like to reclassify your weights, consult with a reputable metrology lab for conversion.

Will I be able to purchase NIST Class F weights after January 1st, 2020?

Generally, NIST Class F weights will not be able to be purchased for legal metrology use after this date. However, due to existing stock, there may be Class F weights available, which would only be able to be used for internal reference weights and not for legal metrology use. Scales Plus will be updating its catalog to include ASTM Class 6 weights from manufacturers like Rice Lake Weighing Systems and Troemner. All NIST Class F listings will be removed from our site beginning in January. If you have any additional questions regarding the 2019 revision to Handbook 105-1 or need help determining which class is suitable for your application, please reach out to our technical team via chat, email, or phone.