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Research paper : Improving the reliability of temperature measurements up to 1550 ℃ (M. Arai et al.)−39−Synthesiology - English edition Vol.3 No.1 (2010) possible to provide the standards with smaller uncertainty in the temperature range up to 1500 °C using the Pt/Pd thermocouple as a transfer standard.7 Conclusion – significance of the Measurement Standards Development ProgramSince the latter half of the 1990s, AIST/NMIJ has been establishing the traceability system by setting the Measurement Standards Development Program based on the social demand in Japan. Of course, the establishment was done by closely following the trends of our industry. The execution of the 10-year period of the Measurement Standards Development Program started in 2001 is now coming to an end. Throughout this period, when and which measurement standards would be prepared and disseminated by AIST were clearly presented to the companies that place importance on quality control including the calibration laboratories. The system was built by discussing a system for measurement standards that was most appropriate to serve the demands for Japan. This means that the necessity of fusing the technological foundation to ensure the reliability that has been built by industry, and the metrology traceability established by AIST/NMIJ, has been well understood.The development of the temperature standards is considered to be an excellent example that promoted the use of JCSS[31]. It was indeed a result of the synchronization of the expanded range of national measurement standards provided by AIST and the vast variety of calibration services conducted by the private companies. This required the integration of the various elemental technologies described in this paper; including the setting of the national measurement standards, the technological development of the transfer standards, the evaluation of uncertainty, the establishment of the quality management system, the execution of the international comparison, the construction of the traceability system, the drafting of the technical documents for calibration, and others. It was a long-term effort that started in the late 1990s, and now, has grown to be a strong system that guarantees the reliability of the temperature measurement up to 1550 °C which has been established in Japan. The authors will continue the technological development for further advancements as described in section 6.3, and will engage in the activities to promote and spread the use of our traceability system.Acknowledgements The authors appreciate Dr. K. Yamazawa and Dr. J. V. Widiatmo (Thermometry section, Temperature and Humidity Division, NMIJ, AIST) for their valuable suggestions upon improving the English translation of this paper. TerminologyThermocouple: Highly practical thermometer made of two different kinds of metal or alloy wires. It can measure extremely low temperature of -270 °C to ultra high temperature of 2400 °C depending on the wire selected. Currently, the Japan Industrial Standard (JIS) designates eight types: types T, J, E, K, and N thermocouples using base metal; and types S, R, and B thermocouples using noble metal.Temperature fixed point: Heat equilibrium where the phase transition occurs at constant temperature. The calibration of thermometers is conducted at this point because it has excellent reproducibility and stability. Some well known fixed points are: the triple points of water (the temperature at which gaseous, liquid, and solid phases coexist) and the freezing point of pure metals such as copper, silver, zinc, and others.Eutectic point: The melting or freezing temperature of alloys when two or more solid phases separate out from a solution and freeze to become a densely mixed substance. The melting or freezing temperature of alloy becomes minimum at the eutectic composition.Japan Calibration Service System (JCSS): This was started as an accreditation system for the calibration laboratories based on the Measurement Act in November 1993, and became a registration system in July 2005. The calibration laboratory undergoes screening to see whether it fulfills the requirements of the calibration institution standard (ISO/IEC 17025) set by the International Standard Organization (ISO) and the International Electrotechnical Commission (IEC). The calibration laboratory is registered if it meets the necessary requirements. The registered laboratory may issue the calibration certificate bearing the JCSS mark.The International Temperature Scale of 1990 (ITS-90): The temperature scale that approximates the thermodynamic temperature based on the international agreement among the member state of the Metre Convention. It is defined by the temperature values at several fixed points and the interpolations (interpolation thermometer and interpolation function). The ITS is reviewed approximately every 20 years, and currently, the temperature scale based on the technique available in 1990 is used.Term 1. Term 2.Term 3.Term 4.Term 5.JIS C 1602, Netsudentsui (Thermocouple). Japanese Standard Association, Tokyo (1995) (in Japanese).H. Numajiri, H. Ogura, M. Izuchi and M. Arai: Uncertainty evaluation on the freezing point of silver for thermocouple [1][2]References

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