Final report of key comparison CCM.P-K3: absolute pressure measurements in gas from 3 X 10-6 Pa to 9 X 10-4 Pa

• Published in: Metrologia 2009-01, Vol.47, p.07004-07004
• Main Authors: Olson, D A, Abbott, P J, Jousten, K, Redgrave, F J, Mohan, P, Hong, S S
• Format: Article
• Language: English
• Subjects: Deviation; Gages; Gauges; Ionization; Metrology; Pressure; Texts
• ISSN: 0026-1394
• DOI: 10.1088/0026-1394/47/1A/07004

This report describes a CCM key comparison of absolute pressure at five national metrology institutes (NMIs) that was carried out from August 1998 to May 2002. The goal of the key comparison was to determine the degree of equivalence of NMI standards at pressures in the range of 3 X 10-6 Pa to 9 X 10-4 Pa. The primary standards were dynamic expansion standards at four of the NMIs and a series expansion standard at the fifth NMI. The transfer standard package consisted of two spinning rotor gauges (SRGs) and three Bayard--Alpert ionization gauges. Due to equipment malfunctions, only one of the ionization gauges was calibrated by all of the participants. The SRG measurements were used to compare NMIs at 9 X 10-4 Pa and to normalize the ionization gauge results at that same pressure. The ionization gauge measurements were used to compare NMIs at the lower pressures. The degrees of equivalence of the NMI standards were determined in two ways: deviations from the key comparison reference value (KCRV), and pairwise differences between those deviations. The standards of four of the NMIs show equivalence to the KCRV and each other over the full range of pressures relative to the expanded uncertainties of the comparisons at the k = 2 level. The standard of one NMI was equivalent to the KCRV at 3 X 10-6 Pa only, and showed lack of equivalence to the standards of one or more NMIs in the range of 9 X 10-6 Pa to 9 X 10-4 Pa. Main text. 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 (MRA).