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.
[1] The Law of Ukraine on Metrology and Metrological Activity, no. 1314-VII dated of 05.06.2014, Kyiv, Ukraine: Parliament publishing house, 2014 (in Ukrainian).
[2] OIML D 1:2012 (E), Considerations for a Law on Metrology: International document, 2012.
[3] OIML V 2:2012 (E/F), International vocabulary of metrology: Basic and general concepts and associated terms, VIM3, 2012.
[4] Sustainable Development Knowledge Platform. Transforming our world: the 2030 Agenda for Sustainable Development, 2015 [Online]. Available: https://sustainab ledevelopment.un.org/post2015/transformingourworld/
[5] The Law of Ukraine on Technical Regulations and Conformity Assessment, No. 124-VIIIІ dated of 15.01.2015, Kyiv, Ukraine: Parliament publishing house, 2015 (in Ukrainian).
[6] ISO 10012:2003, Measurement Management Systems: Requirements for Measurement Processes and Measuring Equipment, 2003.
[7] OIML D 3:1979, Legal qualification of measuring instruments: International document, 1979.
[8] The procedure for verifying of the legally regulated measuring instruments which are in operation, and the registration of its results: Order of the Ministry of Economic Development and Trade of Ukraine no. 193 dated of 08.02.2016, Kyiv, Ukraine, 2016 (in Ukrainian).
[9] Technical regulation of the legally regulated measuring instruments: Approved by the decision of the Ukraine Cabinet Ministers, No. 94 dated of 13.01.2016, Kyiv, Ukraine, 2016 (in Ukrainian).
[10] ISO/IEC 17025:2017, General Requirements for the Competence of Testing and Calibration Laboratories, 2017.
[11] V. Motalo, “Analysis of verification and calibration methodologies of measuring instruments”, in All-Ukrainian scientific and technical conference in the field of metrology “Technical Using of Measurement, 2019”, Slavske, Ukraine, 2019, p. 18–20 (in Ukrainian)
[12] ISO/IEC Guide 98-3:2008, Uncertainty of measurement, Part 3: Guide to the expression of uncertainty in measurement, 2008.
[13] EA-4/02 M: 2013, Expression of the Uncertainty of Measurement in Calibration: European Accreditation, 2013.
[14] M. Dorozhovets, Processing of the measurement results, Lviv, Ukraine: Lviv Polytechnic Publ. House, 2007 (in Ukrainian).
[15] O. Maletskaya, and M. Moskalenko, “Calibration of the Measuring Instruments: Estimation of the Error and Uncertainty of Measurements”, Information Processing Systems, , iss. 3 (110), p. 75–79, 2013 (in Russian).
[16] R. Trysch, M. Moskalenko, and O. Maletskaya, “Calibration Techniques: Developments and Problems”, Information Processing Systems, iss. 1 (99), p. 45–48, 2012 (in Russian).
[17] DSTU GOST 8.237:2008 (GOST 8.237:2003, IDT), Single-value electrical resistance measures: Verification procedure, Kyiv, Ukraine, 2009 (in Ukrainian).
[18] OIML R 111-1, Weights of classes E1, E2, F1, F2, M1, M1-2, M2, M2-3 and M3 Part 1: Metrological and technical requirements, 2004.
[19] I. Zakharov, S. Vodotyka, and E. Shevchenko, “Methods, models, and budgets for estimation of measurement uncertainty during calibration”, Measurement Techniques, No. 4, p. 20–26, 2011 (in Russian).
[20] M. Dorozhovets, V. Motalo, B, Stadnyk, and others, Fundamentals of Metrology and Measuring Technique in two volumes, vol. 2: Measuring Technique; ed. by B. Stadnyk, Lviv, Ukraine: Lviv Polytechn. Publ. House, 2005 (in Ukrainian).
[21] V. Motalo, “Verification of the resistive voltage dividers by resistance ratio measurement method”, Scientific Bulletin of UNFU, vol. 26, No. 1, p. 244–252, 2016 (in Ukrainian).
[22] OIML V 1:2013 (E/F), International Vocabulary of Terms in Legal Metrology (VIML), 2013.
[23] DSYU GOST 8.366:2009. Digital ohmmeters: Methods and means for verification, Kyiv, Ukraine, 2008 (in Ukrainian).
[24] Guidelines on the Calibration of Digital Multimeters: Calibration Guide EURAMET cg-15, version 3.0, 2015.
[25] OIML R 34:1979, Accuracy classes of measuring instruments: International recommendation, 1979.
[26] COOMET R/GM/21:2011, Use of concepts “error of measurement” and “uncertainty of measurement”: General principles, 2011 (in Russian).
[27] OIML D 8 Edition 2004 (E), Measurement standards: Choice, recognition, use, conservation and documentation, International document, 2004.
[28] Guidelines on the Calibration of Non-Automatic Weighing Instruments: EURAMET Calibration Guide, No. 18, version 4.0, 2015.