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SRM/SRD Overview As part of a program to disseminate the International Temperature Scale of 1990 (ITS-90), NIST provides four different types of thermometric Standard Reference Materials® (SRMs®) and one Standard Reference Database® (SRD®). The four thermometric SRMs include small fixed-point cells, large fixed-point cells, high-purity metals for constructing fixed-point cells, and thermometers. Together, they cover the temperature range from –38 °C to 1767 °C. SRMs of small fixed-point cells are for use in calibrating small thermometers, e.g., thermistors, over the range 29.7646 °C to 156.5985 °C. SRMs of large freezing-point cells of tin (231.928 °C) and zinc (419.527 °C) are for use in calibrating standard platinum resistance thermometers in accordance with the ITS-90. SRM metals of Hg, Ga, In, Sn, Zn, Al, and Ag, >99.9999% pure, may be used to construct fixed-point cells that cover the range –38.8334 °C to 961.78 °C. SRMs of NIST-calibrated thermometers (liquid-in-glass, thermocouple, and capsule SPRT) cover the range of –259.35 °C to 1767 °C. The thermometric SRD fully reproduces the tables of NIST Monograph 175, "Temperature-Electromotive Force Reference Functions and Tables for the Letter-Designated Thermocouple Types Based on the ITS-90," by Burns, Scroger, Strouse, Croarkin, and Guthrie. |
Last Updated on: 2/25/04
| Contacts Tests and Fees Calibration Uncertainties Industrial Thermometers Low Temperature SPRTs Thermocouples |
| Bibliography Fixed Points Humidity IPRTs ITS 90 Liquid in Glass Meas. Assurance Publications RTP SPRTs SRMs Tempmeko 2001 Thermistors Thermocouples Thermodynamic |
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Precision Themometry Workshop: ITS 90 Fixed Point Cell Mini Workshop: Liquid In
Glass Thermometer Mini Workshop: |
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Calibration for RTP |
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