Abstract
This paper investigates the discontinuity in the derivative [dW/dT 90]TPW of the ITS-90 at the triple point of water, using data for over 40 calibrated standard platinum resistance thermometers (SPRTs). It finds that the discontinuity is in most cases somewhere between 0 and −6 parts in 105, in relative terms, but that the higher numerical values are obtained for ‘less ideal’ SPRTs (those with lower temperature coefficients of resistance), and also for sub-ranges not extending beyond the indium point. These results are investigated vis-à-vis the long-standing observation that the ITS-90 reference values W r(Ga) and W r(Hg) are not completely consistent with data for W(Ga) and W(Hg) for real SPRTs. It discusses what may be done in a future scale to ensure continuity in the first derivative, and it concludes with a comment about the acceptance criteria for SPRTs in the scale.
Article PDF
Similar content being viewed by others
References
Kemp R.C.: Metrologia 28, 327 (1991)
Crovini L., Jung H.J., Kemp R.C., Ling S.K., Mangum B.W., Sakurai H.: Metrologia 28, 317 (1991)
Supplementary Information for the ITS-90, BIPM (1990) http://www.bipm.org/en/publications/its-90_supplementary.html
Meyer C.W., Tew W.L.: Metrologia 43, 341 (2006)
R.L. Rusby, in The Mercury Point in the ITS-90. CCT/93-29, BIPM (1993)
Singh Y.P., Maas H., Edler F., Zaidi Z.H.: Metrologia 31, 49 (1994)
Hill K.D.: Metrologia 32, 87 (1995)
Pitre L., Moldover M.R., Tew W.L.: Metrologia 43, 142 (2006)
J. Fischer, M. de Podesta, K.D. Hill, M. Moldover, L. Pitre, R. Rusby, P. Steur, O. Tamura, R. White, L. Wolber, Int. J. Thermophys. (submitted)
White D.R., Strouse G.F.: Metrologia 46, 101 (2009)
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Rusby, R.L. The Discontinuity in the First Derivative of the ITS-90 at the Triple Point of Water. Int J Thermophys 31, 1567–1572 (2010). https://doi.org/10.1007/s10765-010-0794-9
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s10765-010-0794-9