: pp. 51-66
Lviv Polytechnic National University

The article focuses on the main problems of metrological confirmation of measuring instruments in accordance with international requirements and considers possible directions of their solution. One of the main tasks of metrology is assurance of the uniformity of measurements, that is, the state of measurements, in which their results are expressed in the legal units, and the characteristics of errors or uncertainty of measurements are known with a certain probability and do not exceed  the established limits. The uniformity of measurements is ensured by the conformity of methods of measurements and measuring instruments to use for their intended purpose. In turn, the suitability of the measuring instruments to use for their intended purpose is determined by the conformity of their metrological characteristics with the established norms. Conformity assessment is the process of proving that the established requirements for a product, process, service, system, entity or body have been met. 

Metrological confirmation is a set of operations required to ensure that measuring equipment conforms to the requirements for  its  intended  use. Metrological  confirmation  of measuring  instruments  generally  includes  their  verification  and  calibration. Verification and calibration procedures of measuring instruments have both common features and certain differences.

The procedure of the experimental part of the metrological confirmation of measuring instruments, both their verification and  calibration,  consists  in  comparing  the  indication, of  the  measuring  instrument,  which  is  being  verified,  whether indication of  the  measuring  instrument,  which  is  being  calibrated,  with  the  standard  quantity  value. Consequently, in both procedures there is a common research object: in the verification procedure it is the indication  of the measuring  instrument,  which  needs  to  be  verified;  in  the  calibration  procedure  it  is  the  indication of  the  measuring instrument, which needs to be calibrated. Accordingly, the methods for implementing the verification and calibration procedures are practically identical. 

One of the key issues in the measuring instruments verification and calibration procedures is the question of estimating the accuracy and reliability of the obtained results. The error of the measuring instrument indication, which is being verified, is the measurand in the verification procedure, and it is determined as the result of indirect measurements. The combined standard  uncertainty  of  the  found  error  value  is  the  accuracy  estimate  of  the  verification  result. The actual  quantity  value,  that  corresponds  to  the measuring  instrument  indication, which  is  being  calibrated,  is  the measurand in the calibration procedure. The expanded uncertainty  of the found actual value,  with confidence level is the accuracy estimate of the calibration result. The obtained values  with confidence level are indicated in the calibration certificate of the measuring instrument.

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