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Platinum Resistance Thermometry Laboratory In a national role, one of the objectives of the Platinum Resistance Thermometry (PRT) Laboratory is to realize, maintain, and disseminate the International Temperature Scale of 1990 (ITS-90) over the temperature range from 83.8 K to 962 °C. Using ITS-90 defined fixed-points, the PRT Laboratory provides calibration of Standard Platinum Resistance Thermometers (SPRTs) and the certification of fixed-point cells to promote national consistency of temperature standards and measurement for the U.S. scientific and industrial communities. The types of industry that require our services include aerospace, chemical, defense related, distilleries, electronics, instrumentation manufacturers, pharmaceutical, secondary calibration facilities and utilities. Further dissemination of the ITS-90 is provided through the use of three types of Standard Reference Materials (SRMs). SRM metals, >99.9999% pure, which may be used to construct ITS-90 defining fixed-point cells that cover the temperature range –38.8334 °C to 961.78 °C. SRMs of large freezing-point cells of tin (231.928 °C) and zinc (419.527 °C) are available for use in calibrating SPRTs in accordance with the ITS-90. 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. These SRMs are used to reduce the uncertainty of the calibration of thermometers performed in-house by industry. Additional dissemination of the temperature scale is performed through the Measurement Assurance Program, consultation with industry, development of new thermometric standards, presentations, and publications. In an international role, and under the directives of the CCT, NIST is involved in several key international comparisons designed to investigate the uncertainty in the realization of the ITS-90 amongst the member national laboratories. As part of one of the key comparison programs, NIST is designated as the coordinating laboratory covering the temperature range from 83.8 K to 661 °C (Key Comparison 3). The fifteen laboratories participating include NIST, BIPM, BNM/INM (France), IMGC (Italy), IRL/MSL (New Zealand), KRISS (Korea), NIM (China), NMi/VSL (Netherlands), NML (Australia), NPL (England), NRC (Canada), NRLM (Japan), PTB (Germany), SMU (Slovakia), and VNIIM (Russia). One of three sets, prepared at NIST, of fixed-point cells of Cd and Ga and an SPRT are being sent from NIST or the sub-coordinating laboratories (PTB and NML) to each of the laboratories for testing and calibration. Additionally, the PRT Laboratory is involved in a second key comparison program (Key Comparison 4) covering the temperature range from 660 °C to 962 °C. The twelve national laboratories are NIST, BNM/INM, IMGC, KRISS, NIM, NMi/VSL, NML, NPL, NRC, NRLM, PTB, and VNIIM with NIST designated as the sub-coordinating laboratory for the America group. Sets of fixed-point cells of Al and Ag and a high-temperature SPRT were being sent from PTB (coordinating laboratory) to the sub-coordinating laboratories (NIST, KRISS and NPL) for initial testing and evaluation. Each sub-coordinating laboratory then sent its set of testing artifacts to the other participating laboratories. Additionally, collaboration with other National Measurement Institutes from other countries helps insure consistency of temperature measurement on an international level. For more information, contact Gregory Strouse at gregory.strouse@nist.gov
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Last Updated on: 2/25/04
