NIST HB 105-1 No Longer Recommends NIST Class F Weights

Have you heard about changes to NIST Handbook 105-1? NIST Class F Scale Weights and Test Weights have been replaced by ASTM Class 6 and Troemner has you covered.

Significant changes were made by NIST for the designation of Class F weights and NIST no longer recommends the purchase of new Class F field weights.

As of January 1st, 2020, NIST HB 105-1 requires that no new NIST Class F weights should be placed in service for use of testing commercial weighing equipment.

As a metrologist, if you manage a calibration service department and have Class F weights in service, these changes may affect your weighing processes currently or in the future.

At Troemner we have considered this recommendation and have replaced NIST Class F weights with ASTM Class 6 scale weights, test weights, and weight sets.

Affected products include any of the following commonly referred to product types:

• Class F weights
• NIST Class F
• NIST calibration weights
• NIST traceable weights
• Class F calibration weights
• Class F weight set
• NIST certified weights
• NIST class f calibration weights
• NIST class f weights
• NIST weight set
• Class F test weights for scales

To shop the complete selection of ASTM Class 6 weights which have replaced NIST calibration weights visit:

ASTM Class 6 Individual Weights

ASTM Class 6 Weight Sets

ASTM Class 6 Hooked Weights and Hooked Weight Sets

ASTM Class 6 Slotted Weights and Slotted Weight Sets

ASTM Class 6 Calibration Weight and Storage Carts

ASTM Class 6 weights are available with varying designs including grip handle, cylindrical, cube, flat, hooked, slotted and are available in cast iron or stainless steel. Certified weights and weight sets are available with calibration certificate traceable to NIST or ISO/IEC 17025 Accredited Certificate.

Watch to learn more about changes to NIST Handbook 105-1

Background

Improvements in technology have led to more Class I & II scales being used in commercial applications.

With high precision scales being more commonplace, NIST found that many of these devices were being calibrated using low precision Field Weights.

Due to this, NIST determined the need for a more detailed categorization of "Field Weights" in order to effectively categorize the discrepancy between precision balances and weights. Download the NIST 105-1 Handbook

Status of Class F Weights

As of January 1st, 2020, NIST HB 105-1 stated that no new NIST Class F weights should be placed in service for use of testing commercial weighing equipment.

Existing NIST Class F weights can still be used, provided they demonstrate mass stability. However, their usage should be limited to weighing systems with accuracy classes of III, IIIL, and IIII.

NIST does not recommend Class F weights be reclassified to an ASTM or OIML classification.

What Weights Should I Use Now?

For the purchase of new field weights, NIST now recommends the following:

• ASTM E617, Standard Specification for Laboratory Weights and Precision Mass Standards: Weight Classes 1, 2, 3, 4, 5, and 6
• OIML R111-1, International Recommendation, Weights of Classes: F₁, F₂, M₁, M_1-2, M₂, M_2-3 and M₃

See that chart below to see which of the ASTM and OIML weight classes meet the needs of your weighting device. You should always consult NIST Handbook 44 to verify the proper mass standard for your scale or balance. You should also check with your scale or balance manufacturer to verify the proper mass standard for your device. Additionally, you should always read the manufacturers instruction manual for any additional guidelines.