Evaluation of Laboratory Performance Through Interlaboratory Comparison

摘要

This paper reports the performance of the calibration results obtained by 21 laboratories using digital pressure calibrator as an artifact in the pressure range 7-70 MPa. National Physical Laboratory (NPLI), New Delhi has coordinated this programme and also acted as a reference laboratory. The program started in May, 2006 and completed during May, 2008. The comparison was carried out at 10 equally spaced pressure points i.e. 7, 14, 21, 28, 35, 42, 49, 56, 63 and 70 MPa throughout the entire pressure range of 7-70 MPa. The calibration results thus obtained were analyzed as per ISO/IEC GUM document. The 92.7percent measurement results are found in agreement with the results of NPLI. The relative deviations between laboratories values and reference values are well within the 0.05percent for 123 measurement points, 0.1percent for 162 measurement points and 0.25percent for 177 measurement points. The difference of the laboratories values with reference values are found almost well within the uncertainty band of the reference values at 68.0percent measurement results, within their reported expanded uncertainty band at 81.5percent measurement results and within the combined expanded measurement uncertainty band at 92.7percent measurement results. Overall, the results are considered to be reasonably good being the first proficiency testing for most of the participating laboratories.