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measuring instruments because they will not have the same
assignment, calibration or verification. Consequently, the mode of
management concerning them, choice, identification and conservation
of the references, will have to be clearly defined.
The management of the standards will have to take into account:
– the metrological level of the standard;
– the technical level and the complexity of the standard;
– the abilities of the users;
– the assignment of the standard (reference, work standard, etc.);
– the importance of the standard for the firm;
– special cases of utilization.
All this information must be described in simple and accessible
documents, because it concerns the references of the measurements
made by the firm. An error made on a standard can have more serious
consequences than one made on a measuring instrument. When you
select a standard, you have to take metrological, technical and
economic aspects into account.
The metrological aspects are about the following:
– the methods that can be used to compare the measuring instrument
submitted to calibration to the standard, as well as to calibrate or
verify the standard itself;
– the assessment of the results of the measurements made with the
standard;
– the basic metrological characteristics of the standard, that is, the
accuracy, the stability and the metrological reliability.
Note 1: the accuracy of a standard is established either:
– by comparing it to a reference standard of a superior order and of the
same quantity; or
– by assessing its errors using methods and means of measurement
(for example, standards of other quantities, calibration devices, etc.)
that make it possible to preserve the compatibility of the standard with
the national standards.
Note 2: you realize a standard is stable and metrologically reliable:
– by studying the working principle, the conception and the structure
of the standard and coming to an opinion about them;
– by scrutinizing the materials that make up its structure, the method
of manufacture and assembly;
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