Final report on key comparison APMP.M.P-K7.3 in hydraulic gauge pressure from 10 MPa to 100 MPa

Abstract

Main textThis report describes the results of a key comparison among hydraulic high pressure standards that have been maintained by seven National Metrology Institutes (NMIs: NIMT, NMIJ/AIST, NPLI, RCM-LIPI, NMIM, VMI and NMLPHIL). This comparison was carried out during the period March 2016 to October 2017 within the framework of the Asia-Pacific Metrology Programme (APMP) in order to determine their degrees of equivalence in the pressure range from 10 MPa to 100 MPa, gauge mode. The pilot institute was the National Institute of Metrology (Thailand) (NIMT). All participating institutes used hydraulic pressure balance as their pressure standards. In order to ensure reliability, two high precision pressure transducers were used as the transfer standard. The sensing element of the transducers was a precision quartz crystal resonator attached to a small Bourdon tube. During the comparison, the transfer standard was calibrated at the pilot institute two times, before and after circulating the transfer standard to participants. From the two NIMT calibration results, the transfer standard was sufficiently stable to meet the requirements of the comparison. The long-term instability obtained from the two calibration results was taken into account as the uncertainty of the transfer standard for all participants. As the matter of fact NPL India and NMIM participated in this comparison as one of the linkage institutes and participating institutes, respectively. However, it was found later that the systems of hydraulic pressure balance reference standards used in this comparison were not functioning. Therefore, the comparison results were withdrawn. The degrees of equivalence of each national measurement standard were expressed quantitatively by deviations from the key comparison reference value of the corresponding CCM key comparison, CCM.P-K7 through the linkage institute, NMIJ/AIST. In conclusion, the hydraulic pressure standards in the range 10 MPa to 100 MPa, gauge mode of the five participating NMIs were found to be equivalent within their claimed uncertainties.To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/.The final report has been peer-reviewed and approved for publication by the CCM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).