Intralaboratory quality control of calibration results

Abstract

The article is devoted to the issues of intralaboratory control of measurement results in a calibration laboratory. This is highly important in controlling and supporting the relevant calibration capability of the laboratory. Up to now, there are normative documents, which describe methods for controlling internal quality indicators of analytical measurements. After analyzing all possible options of comparing the quality indicators of the measurement results with critical values in the analytical laboratories and adapting them to the measurement features of the calibration laboratory, the methods of determining the critical limits for comparative measurements in the conditions of repeatability and intermediate precision are demonstrated.Measurement uncertainty in calibration consists of uncertainty effects introduced by reference equipment, test equipment, calibration operator, external conditions, calibration and calculation method, measuring instrument (MI), which is to be calibrated. Proceeding from the well-known practice, the calibration capability of the laboratory should be three to five times smaller than the uncertainty of MIs being calibrated by this laboratory. In order to maintain such a level of calibration, it is necessary to perform timely calibrations of the measurement standards and test equipment (to carry out internal testing of test equipment), validate calibration methods, participate in interlaboratory comparisons in order to determine laboratory bias and perform intralaboratory control of the quality indicators of measurement results in calibration.Several methods of intralaboratory control of measurement results in a calibration laboratory are proposed, namely, the evaluation of consistency of the measurement results in calibration in conditions of intermediate precision with variable factors “operator”, “time” and determination of the limits of repeatability.