Rice Lake Weighing Systems is an international leader in the manufacture and distribution of weight-related products and process-control equipment. Within this ISO 9001 registered company, progressive new technologies merge with the wisdom of industry experience and create the future of weighing through cutting-edge research and design.
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Beginning January 1, 2020, Rice Lake Class F calibration weights will no longer be sold for legal metrology use. According to the newly updated NIST Handbook 105-1 (2019), new weights for use as field standards placed into service for weights and measures use after this date must comply with all of the requirements of NIST Handbook 105-1 (2019). In order to update our Class F inventory to bring it more in line with ASTM and OIML tolerances, all Rice Lake NIST Class F weights will become ASTM Class 5 weights. Part numbers and pricing will remain the same, but the tolerance will be tighter.
Note that existing NIST Class F calibration weights in the field are grandfathered in and may continue to be used for legal metrology use, but they must 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.
While 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, 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.
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, marijuana and pharmaceutical industries. Similarly, hydrogen for hydrogen vehicles is being sold by weight, which demands a high level of accuracy.
Class 0 Used as a primary reference for calibrating other reference standards and weights. Class 0 weights are intended to be used in metrology laboratories where the stability of the environment and careful handling are assured. Although very stable, one-piece construction Class 0 weights have no method of adjustment and are not suitable for general laboratory use. The uncertainty is guaranteed to be 1/3 the tolerance.
Class 1 - Can be used as a reference standard in calibrating other weights and is appropriate for calibrating high-precision analytical balances with a readability as low as 0.1 mg to 0.01 mg.
Class F - Now Class 5 - Primarily used to test commercial weighing devices by state and local weights and measures, device installers, and service technicians.
OIML Class E1 Weights manufactured to international recommendation, OIML R111 specifications would be used to calibrate Class I/II balances, balances accurate as 0.001mg, and as a laboratory standard. These classes are considered to be of extra-fine accuracy.
OIML Class E2 Weights manufactured to international recommendation, OIML R111 specifications would be used to calibrate Class I/II balances, balances accurate as 0.001mg, and as a laboratory standard. These classes are considered to be of extra-fine accuracy.
OIML Class F1 Suitable for use for traceability of OIML class F2 weights and lower; also with OIML accuracy class I weighing instruments. The maximum permissible error from nominal value at 1 kg is +5 mg. For the calibration of high accuracy class 2 balances.
OIML Class F2 Suitable for use for traceability of OIML class M1 weights and lower; also with OIML accuracy class II weighing instruments. Intended for use in high value commercial transactions such as gold and precious stones. The maximum permissible error from nominal value at 1 kg is +16 mg. Used as working standards for precision and analytical work, build-in weights, external weights to calibrate moderate precision balance
OIML Class M1 Suitable for use for traceability of OIML class M2 weights and lower; also with OIML accuracy class II weighing instruments. The maximum permissible error from nominal value at 1 kg is +50 mg.
OIML Class M2 Suitable for use for traceability of OIML class M3 weights; also with OIML accuracy class III weighing instruments. Intended for use in normal commercial transactions where goods are sold by weight. The maximum permissible error from nominal value at 1 kg is +160 mg. Used for accuracy class III applications, industrial scales, dial scales, trip balances, platform scales
Class 0 Used as a primary reference for calibrating other reference standards and weights. Class 0 weights are intended to be used in metrology laboratories where the stability of the environment and careful handling are assured. Although very stable, one-piece construction Class 0 weights have no method of adjustment and are not suitable for general laboratory use. The uncertainty is guaranteed to be 1/3 the tolerance.
Class 1 - Can be used as a reference standard in calibrating other weights and is appropriate for calibrating high-precision analytical balances with a readability as low as 0.1 mg to 0.01 mg.
Class 5 - Class F - Primarily used to test commercial weighing devices by state and local weights and measures, device
installers, and service technicians. Note All Class F wieghts are now Class 5
Specialty Calibration Weights - Class 6 - Class 7 - Class F
OIML Class E1 Weights manufactured to international recommendation, OIML R111 specifications would be used to calibrate Class I/II balances, balances accurate as 0.001mg, and as a laboratory standard. These classes are considered to be of extra-fine accuracy.
OIML Class E2 Weights manufactured to international recommendation, OIML R111 specifications would be used to calibrate Class I/II balances, balances accurate as 0.001mg, and as a laboratory standard. These classes are considered to be of extra-fine accuracy.
OIML Class F1 Suitable for use for traceability of OIML class F2 weights and lower; also with OIML accuracy class I weighing instruments. The maximum permissible error from nominal value at 1 kg is +5 mg. For the calibration of high accuracy class 2 balances.
OIML Class F2 Suitable for use for traceability of OIML class M1 weights and lower; also with OIML accuracy class II weighing instruments. Intended for use in high value commercial transactions such as gold and precious stones. The maximum permissible error from nominal value at 1 kg is +16 mg. Used as working standards for precision and analytical work, build-in weights, external weights to calibrate moderate precision balance
OIML Class M1 Suitable for use for traceability of OIML class M2 weights and lower; also with OIML accuracy class II weighing instruments. The maximum permissible error from nominal value at 1 kg is +50 mg.