Evaluation of interlaboratory performance through proficiency testing using pressure dial gauge in the hydraulic pressure measurement up to 70 MPa

The present paper reports the results of the proficiency testing (PT) accomplished for 17 laboratories, accredited by National Accreditation Board for Testing and Calibration of Laboratories (NABL). The measurements were performed in the pressure range 10-70 MPa using pressure dial gauge as an artifact. Only laboratories having best measurement capabilities 0.25 % or coarser than 0.25 % of full-scale pressure were included in this PT. The program started in May 2006 and completed during October, 2007. The comparison was carried out at 10 arbitrarily chosen pressure points i.e. 10, 20,30, 40,45,50,55, 60, 65 and 70 MPa. The results thus obtained show that out of the total 159 measurement results, 135 (84.91 %) are found in good agreement with the results of the reference laboratory. The relative deviations between laboratories values and reference values are well within 0.15 % for 75 measurement points, 0.25% for 108 measurement points and 0.50% for 148 measurement points. The difference of the laboratories values with reference values are found almost well within the uncertainty band of the reference values at 71.07 % measurement results, within their reported expanded uncertainty band at 62.26% measurement results and within the combined expanded measurement uncertainty band at 84.91 % measurement results. Overall, the results are considered to be reasonably good, being the first proficiency testing for most of the participating laboratories