APMP key comparison of absolute pressure from 10 kPa to 110 kPa (APMP.M.P-K9)
Authors: Choi In-Mook , Woo Sam-Yong , Man John , Aldammad Mohamad , Sabuga Wladimir , Jin Yue , Thang Nguyen Nam , Wu Gwo-Jen , Sutton Chris , Kojima Momoko , Changpan Tawat , Kin Chan Tak , Hayu Renanta 
Published: April 2020

This report describes the results of a key comparison of pneumatic pressure standards which was carried out at fourteen National Metrology Institutes (NMIs: NMIA, NSCL, PTB, NIM, VMI, CMS/ITRI, MSL, NMIJ/AIST, NMC A*STAR, NIMT, SCL, NIS, RCM-LIPI and KRISS) during the period of February 2010 to July 2012 within the framework of the Asia-Pacific Metrology Programme (APMP) in order to determine their degrees of equivalence at pressures in the range 10 kPa to 110 kPa in absolute mode. Among them, twelve NMIs' results were compared in the report. The pilot laboratory was Korea Research Institute of Standards and Science (KRISS). The degrees of equivalence in this comparison were transferred to the corresponding CC key comparison, CCM.P-K2. National Measurement Institute, Australia (NMIA) and Physikalisch-Technische Bundesanstalt (PTB) that participated in the CC comparison agreed to be link laboratories.
Most of the participating institutes used pneumatic pressure balances as their pressure standards while two link laboratories used laser interferometer mercury manometers. Precise absolute pressure gauges were used as transfer standards (TSs). The precision pressure gauge has two Quartz-Resonant Pressure Transducers (Q-RPTs) inside. Two identical transfer packages (TS-A and TS-B) were circulated independently to reduce the time required for the measurements. During the comparison, intermediate measurements of two circulated transfer standards were carried out in the pilot laboratory after one or two NMIs measurement and third transfer standard (TS-C) was monitored for the stability characterization, also. The pressures of the comparison were (10, 30, 50, 70, 90, 100, 110) kPa. From the calibration results, the behaviours of the transfer standards during the comparison period were well characterized and it was concluded that the performance of the transfer standards were sufficient in the comparison pressure range except 10 kPa. The TSs used in this comparison were not suitable for the low pressure measurement like 10 kPa because of low display resolution of TS (1 part in 105 at 10 kPa). The degrees of equivalence of each national measurement standard were expressed quantitatively by two terms, deviations from the key comparison reference values (KCRVs) and pair-wise differences of their deviations together with the associated uncertainties. The pneumatic pressure standards in the range 30 kPa to 110 kPa for absolute mode of all participating NMIs were found to be equivalent within their claimed uncertainties.

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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 kcdb.bipm.org/.
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).