Description: Carrying out calibration of measuring instruments allows to establish a ratio between values of sizes which provide standards, and the corresponding indications of measuring instruments. Considering that measuring instruments have some instability, the question is undoubtedly relevant: how it is long possible to apply the ratio established at calibration between indications of measuring instruments and the corresponding values appropriated to them? Management of ILAC-G24/OIML D 10: 2007 offers 5 methods of definition of intervals between calibrations of measuring instruments. However these methods are only listed in the Guide, but do not open many questions of their practical application. Article purpose – to formulate practical recommendations about establishment of intervals between calibrations of measuring instruments. The methodology of carrying out researches consists in the following. It is supposed that the component from instability of a measuring instrument on short intervals of time is linear function of time with proportionality coefficient. Then the calibrated measuring instrument can continue to be used until eventually (because of instability of a measuring instrument) the expanded measurement uncertainty does not exceed some in advance accepted maximum allowed measurement uncertainty. As a result ratios between the specified uncertainty, the coefficient of proportionality mentioned above and an interval between calibrations of measuring instruments are established. Practical examples of determination of coefficient of a proportionality of linear dependence of the making uncertainty caused by instability of a measuring instrument from time are given. The conclusion is drawn on expediency of application of the offered approach for an establishment of intervals between calibrations of measuring instruments.
Keywords: calibration, interval between calibrations, measuring instruments, measurement uncertainty
1. JCGM 200:2012, International vocabulary of metrology – Basic and general concepts and associated terms (VIM), available at: https://www.bipm.org/utils/common/documents/jcgm/JCGM_200_2012.
2. ILAC-G24/OIML D 10: 2007, Guidelines for the determination of recalibration intervals of measuring equipment used in testing laboratories, available at: https://www.oiml.org/en/files/pdf_d/d010-e07.pdf.
3. Zakharov, I.P., Vodotyka, S.V. and Shevchenko, E.N. (2011), “Metody, modeli i byudzhety ocenivaniya neopredelennosti izmerenij pri provedenii kalibrovok” [Methods, models, and budgets for estimation of measurement uncertainty during calibration], Measurement Techniques, Vol. 54, No. 4, pp. 20-26. https://doi.org/10.1007/s11018-011-9737-5.
4. OIML G19:2017, The role of measurement uncertainty in conformity assessment decisions in legal metrology, available at: https://www.oiml.org/en/files/pdf_g/g019-e17.pdf.
5. COOMET R/GM/32:2017, “Kalibrovka sredstv izmerenij. Algoritmy obrabotki rezul'tatov izmerenij i ocenivaniya neo-predelyonnosti” [Calibration of measuring instruments. Algorithms for processing measurement results and estimating uncer-tainty], available at: https://www.coomet.net/fileadmin/user_files/DOCUMENTS/COOMET_Documents/Pecommenda-tions/COOMET_R_GM_32_2017_ru.pdf.