ASME B89.7.6:2019 pdf free download.Guidelines for the Evaluation of Uncertainty of Test Values Associated With the Verification of Dimensional Measuring Instruments to Their Performance Specifications.
The rated operating conditions are generally stated by the instrument manufacturer. They are the conditions under which the instrument has a performance specification, i.e., the MPE specification exists only within the rated operating conditions. The rated operating conditions can be considered the domain of a function whose value is the MPE
Often the MPE value is constant or slowly varies over wide ranges of an operating condition; e.g., the same MPE value might be quoted for the performance of an instrument over the entire range of the rated ambient temperatures. Envronmental conditions are frequently included among the rated operating conditions; however, many other factors can also be included. The quantity under measurement is a rated condition, e.g.. the M PE for a micrometer generally increases as the length of the calibrated reference length increases. Any influence that is specified or constrained in some manner as a requirement to achieve the instrument’s performance specification is an operating condition; this includes require. ments described in the instrument’s operating manual. When tested under conditions that satisfy the rated operating conditions, an instrument conforming to its performance specification shall yield an error of indication no greater than its MPE value.
4.3 Test Conditions
The test conditions are the particular conditions that prevail at the moment the test value is obtained. Often the test conditions are within the rated operating conditions of the instrument under test. In some cases, the test conditions will — as explicitly permitted by the testing protocol — be outside the rated operating conditions and require a correction to create an indicated value from the instrument that is associated with conditions that are within the rated operating conditions. As described in para. 5.3, In some cases this correction is numerically zero, but there are still test value uncertainties associated with the zero correction. Conceptually, the correction creates an indicated value that is associated with conditions within the rated operating conditions and hence can be compared to the MPE. For example, ASME B89.1.13 has (for historical reasons) defined the test measurand as the measurement error of a micrometer at (and only at) 20°C. Hence an MPE specification exists only at the operating condition of 20°C. whereas test conditions will inevitably occur at other temperatures. In this case, corrections are required — and permitted by the protocol — to adjust the indicated value of the instrument to produce a value the instrument would have produced if the test had been conducted at 20°C (thus satisfying the rated operating conditions) and producing a test value that can be compared to the MPE specification.
ASME B89.7.6:2019 pdf free download
