Final report on EURAMET.T-K3.1: Bilateral comparison of the realisations of the ITS-90 at the fixed points of Hg, H₂O, Ga, Sn and Zn

Abstract

A bilateral comparison has been organized between VSL, The Netherlands, and BIM, Bulgaria, of the realisations of the international temperature scale ITS-90 at the fixed points of Hg, H2O, Ga, In, Sn and Zn using a long-stem SPRT of very good stability as the transfer device. This comparison is registered as EURAMET project T-K3.1 in the BIPM key comparison database and its results are linked to those of key comparison CCT-K3.This comparison was organized in the framework of Phare project BG 2005/017-353.02.02, Lot 1, and is in this framework financed by the EU. This project ran from March 2008 to the end of February 2009.For all points of the measurements, a good agreement between the results obtained by BIM and in CCT-K3 could be demonstrated.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 CCT, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Calibration of hygrometers at non-static conditions

“…The estimated expanded uncertainty (k = 2) of the nonstatic calibration at 50 %rh and 25 °C was 0.6 %rh and 1.2 %rh when using a chilled mirror hygrometer and a capacitive humidity sensor as a reference, respectively. This is at the same level as typically reported for reference hygrometerbased relative humidity calibration systems applying a static calibration procedure [8][9][10][11][12][13][14]. Tables 2 and 3 indicate an excess of 0.19 %rh and 0.03 %rh in expanded uncertainty due to the non-static procedure when using a chilled mirror hygrometer and a capacitive humidity sensor as a reference, respectively.…”

A new interpolation equation in the ITS-90 subrange from the triple point of water to the freezing point of indium

“…Using a data set of 30 SPRTs calibrations from various countries and laboratories [22][23][24][25][26][27][28][29], the SRIs between the new equation and the reference piecewise function are calculated and analysed. The peak value of SRIs shows a significant decrease to 0.21 mK compared to that of ITS-90 in the same subrange which is 0.91 mK and shows a reduction of 77%.…”

“…In this section, SRI, NU3 and PoU of the proposed interpolation equation are discussed respectively. Data collection and preparation for SRI are composed of two parts: the historical data from a series of CCT reports [22][23][24][25][26][27][28][29] and the experimental data run for this study. NU3 analysis is based on the experimental data run for this study solely.…”