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.

Standard Reference Material 1749: Au/Pt Thermocouple Thermometer



Dean C. Ripple, G W. Burns


Standard Reference Material (SRM) 1749 is a lot of 18 specially-constructed gold versus platinum (Au/Pt) thermocouple thermometers, each calibrated on the International Temperature Scale of 1990 (ITS-90) and supplied with integral lead wires and a protective sheath. It is the most accurate thermocouple available over the range 0 C to 1000 C, with an expanded uncertainty (k=2) less than 8.3m C from 0 C to 962 C, and rising to 14 m C at 1000 C. We describe the fabrication and calibration methods used to prepare the SRM 1749 thermocouples. These thermocouples are exceptionally thermoelectrically homogeneous and stable over hundreds of hours of use, making them an excellent choice as a secondary reference thermometer. To facilitate low measurement uncertainties in applications, practical methods for emf measurements and comparison calibrations of other thermometers with the SRM 1749 thermocouple are also given.
Special Publication (NIST SP) - 260-134
Report Number


gold, platinum, thermocouple, thermometer


Ripple, D. and Burns, G. (2002), Standard Reference Material 1749: Au/Pt Thermocouple Thermometer, Special Publication (NIST SP), National Institute of Standards and Technology, Gaithersburg, MD (Accessed July 24, 2024)


If you have any questions about this publication or are having problems accessing it, please contact

Created March 1, 2002, Updated October 16, 2008