A computer program implements several aspects of the International Temperature Scale of 1990 (ITS90).

• For platinum resistance thermometers (PRTs), the program can perform reference- function (Wref) calculations traceable to the National Institute of Standards and Technology (NIST) through its Technical Note 1265. Wref represents a perfect PRT that has a resistance of exactly 1 Ω at the triplepoint temperature of water. The program provides for the entry of coefficients generated by a calibration facility and converts a measured resistance to an equivalent temperature with an accuracy of 5 millikelvins. The program also performs measurement calculations for PRTs: In such a calculation, the triple-point temperature of water as determined by a calibration laboratory is multiplied by the applicable NIST reference value.

• The program converts between output voltages and temperatures for several types of thermocouples that yield measurements traceable to NIST through its Monograph 175. These thermocouples are of types T (Cu/Cu-Ni), K (Ni- Cr/Ni-Al), J (Fe/Cu-Ni), E (Ni-Cr/Cu- Ni), N (Ni-Cr-Si/Ni-Si-Mg), B [Pt(30 percent)-Rh/Pt(6 percent)-Rh], S [Pt(10 percent)-Rh/Pt], and R [Pt(13 percent)-Rh/Pt].

This program was written by Richard T. Deyoe of Dynacs, Inc., for Kennedy Space Center. For further information, access the Technical Support Package (TSP) free online at www.nasatech.com/tsp  under the Software category. KSC-12166


NASA Tech Briefs Magazine

This article first appeared in the March, 2002 issue of NASA Tech Briefs Magazine.

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