CALIBRATION METHODS AND MEASUREMENT UNCERTAINTY

Torque wrenches

Calibration procedure of torque wrenches is based on MKS EN ISO 6789:2003 standard - Assembly tools for screws and nuts -- Hand torque tools -- Requirements and test methods for design conformance testing, quality conformance testing and recalibration procedure.

According to the recommendation in MKS EN ISO 6789:2003 standard, the calculation of measurement uncertainty is carried out by the Guide from The International Bureau of Weights and Measures – BIPM - Evaluation of measurement data – Guide to the expression of uncertainty in measurement: JCGM 100:2008.

Force measuring devices – dynamometers

Calibration of force measuring devices-dynamometers is conducting according to MKS EN ISO 376:2011 standard - Metallic materials -- Calibration of force-proving instruments used for the verification of uniaxial testing machines.

Calculating and presentation of measurement uncertainty is based on Annex C of MKS EN ISO 376:2011, but for better definition and understanding of the impact of individual components on the expanded uncertainty, the Guide from The International Bureau of Weights and Measures – BIPM is also used.

Machines for testing metallic materials

Calibration of force measuring system at material testing machines is carried out according to MKS EN ISO 7500-1:2004 standard - Metallic materials -- Verification of static uniaxial testing machines -- Part 1: Tension/compression testing machines -- Verification and calibration of the force-measuring system.

Calculating and presentation of measurement uncertainty is based on Annex D of MKS EN ISO 7500-1:2004, but for better definition and understanding of the impact of individual components on the expanded uncertainty, the Guide from The International Bureau of Weights and Measures – BIPM is also used.

Uniaxial material testing machines

Calibration of force measuring system at uniaxial material testing machines is carried out according to MKS EN 12390-4:2000 - Testing hardened concrete - Part 4: Compressive strength - Specification for testing machines.

The MKS EN 12390 standard in the segment of describing the process of measurement, calculation and presentation of results, as well as in the classification of testing machines does not use the term measurement uncertainty. Instead, the standard at each nominal level provides the repeatability and the error in terms of force to be expressed as a percentage of the nominal force.

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