Skip to main content
U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

NIST Certification of ITS-90 Fixed-Point Cells From 83.8058 K to 1234.93 k: Methods and Uncertainties

Published

Author(s)

Gregory F. Strouse

Abstract

The certification of ITS 90 fixed-point cells from the Ar triple point (83.8058 K) to the Ag freezing point (1234.93 K) is an integral part of the calibration services offered by the NIST Thermometry Group. This service is used to qualify new fixed-point cells for internal use within the NIST Thermometry Group and by those facilities seeking traceability to NIST for the ITS-90 calibration of SPRTs. The method of certifying an ITS-90 fixed-point cell is a multiple step process that is designed to evaluate the intrinsic repeatability of the fixed-point cell, evaluate the realized temperature difference between the test fixed-point cell and the NIST reference fixed-point cell, assess the interaction of the fixed-point cell with the furnace and SPRT, and estimate the uncertainty of the certification process. This paper gives results of the reproducibility of direct comparison measurements over time, furnace effects on the realized fixed-point temperature, the certification uncertainty budget, and an uncertainty budget showing the required measurements that an end user must perform to assign an uncertainty in the use of the fixed-point cell.
Citation
TEMPMEKO

Keywords

direct comparison, fixed-point cell, fixed-point cell certification, International Temperature Scale of 1990, ITS-90, SPRT, standard platinum resistance thermometer

Citation

Strouse, G. (2005), NIST Certification of ITS-90 Fixed-Point Cells From 83.8058 K to 1234.93 k: Methods and Uncertainties, TEMPMEKO, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=830876 (Accessed July 21, 2024)

Issues

If you have any questions about this publication or are having problems accessing it, please contact reflib@nist.gov.

Created January 1, 2005, Updated February 19, 2017