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ASME B89.7.6-2019
Guidelines for the Evaluation of Uncertainty of Test Values Associated with the Verification of Dimensional Measuring Instruments to Their Performance Specifications
The primary purpose of this Standard is to provide guidance for assessing the uncertainty of test values associated with the verification of dimensional instruments to their ASME B89 performance specifications. This guidance is fully consistent with the GUM methodology and philosophy. The particular case of verifying dimensional instruments is frequently misunderstood by practitioners. This confusion arises primarily because the measurand of the verification is the instrument's measurement error when measuring the calibrated reference quantity specified in the testing protocol. The test values produced during ASME B89 testing are estimates of these measurement errors. Hence, in verification testing, the performance of the instrument is the quantity being measure. The instrument is verified as complying with its ASME B89 performance specification if the test values are within the instrument's maximum permissible error (MPE) and satisfy the decision rule sated in teh testing protocol. To ensure that this verification is metrologicialy traceable, the uncertainty in the test values must be evaluated, i.e., the practitioner must determine how well each test value estimates the measurement error made by the instrument under verification when it is used to measure the reference quantity specified by the testing protocol. By distinguishing the instrument under verification form the measurement system performing the verification, the evaluation of uncertainty of the test values is shown to follow the GUM procedure. ASME B89.7.6 provides both detailed discussions and worked examples to clarify this issue and should prove valuable to both novice and experiences metrologists.
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American Society of Mechanical Engineers [asme]
