The work is in developing methods for determining the intervals between calibration (recalibration intervals) of working standards and measuring instruments used in testing and calibration laboratories, aimed at ensuring metrological traceability, accuracy and reliability of measurement results. The theoretical and experimental substantiation of the developed methods is given. Ensuring the unity and metrological traceability of measurement results has become a key component of confidence in experimental procedures based on measurement results. An important aspect of maintaining a laboratory's ability to obtain statistically reliable results is to determine the maximum allowable time interval between two calibrations of standards and measurement equipment. At the same time, it is necessary to solve the problem of ensuring the necessary accuracy of measurements during their use and to establish a real interval between calibrations. Therefore, each test or calibration laboratory that seeks to provide confidence in the results of its own measurements should set recalibration intervals for the equipment used or enter criteria to determine the need for calibration. The analysis of existing approaches to the determination of the recalibration intervals of measuring equipment is carried out. According to the results, the practice of applying the classical reliability theory for estimation of metrological reliability of measuring equipment, which does not take into account the peculiarities and conditions of their use, is quite widespread and too generalized. It has been found that methods based on the use of control charts can give timely signals about changes in metrological characteristics of measuring equipment and the need for their calibration. Theoretical substantiation of expediency using the Shewhart control charts of the mean values with the lines of the exponentially weighted moving averages is given. This allows you to smooth out random «misses» on the control charts, as well as detect long-term, not noticeable for the classic use of control charts, shift (drift) of measuring equipment metrological characteristics. On the basis of the conducted researches a new complex method for detecting the drift of metrological characteristics of measuring equipment was proposed. The possibility of controlling the conformity of metrological characteristics of standards and measuring instruments with the established normative values with the use of cumulative sum charts (CUSUM-charts) is investigated in the work. The principles of construction of these charts, the features of detecting the moment of change in the metrological characteristics of measuring equipment are shown. After analyzing the causes of delayed signals on CUSUM-charts and the disadvantages that cause them, a new method of sliding regression on the CUSUM-charts was proposed. The method is based on a comparison of the slope angle of a regression line drawn at several consecutive points on a map, which is constructed using the equivalent straight numerical method, with the calculated maximum allowable. It is shown theoretically and proven experimentally that the use of the sliding regression method allows to reduce the delay time of the signal output of metrological characteristics of standards or measuring equipment beyond the established limits. A new approach to the control of the state of measurement equipment by analyzing the standard deviation of the results of observations is presented, which reflects a decrease in sensitivity. The concept of critical sequence of points is introduced, the occurrence of which indicates the change of sensitivity over time of the measuring equipment. For this purpose, it is proposed to divide Pearson's distribution into elementary intervals by mode and median. Appropriate calculations have been made and a performance criterion has been introduced that indicates the feasibility of applying an approach. Based on the performed calculations and researches, an adaptive algorithm for the detection of the critical sequence of standard deviation points is proposed, which allows to control the status of working standards and measuring equipment, based on the obtained standard deviation of measurement results at control points. Experimental verification of the proposed methods was carried out, in which case it is necessary to apply one or another method. Keywords: calibration, recalibration interval, standard, measuring instrument, control chart, intermediate check, metrological traceability, critical sequence of points, adaptive algorithm.
