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Research paper : Improvement of reliability in pressure measurements and international mutual recognition (T. Kobata et al.)−225−Synthesiology - English edition Vol.4 No.4 (2012) AuthorsTokihiko KobataCompleted the doctorate courses at the Department of Physical Engineering, Graduate School of Engineering, Tsukuba University in 1995. Doctor (Engineering). Joined the National Research Laboratory of Metrology, Agency of Industrial Science and Technology, Ministry of International Trade and Industry in 1995. Senior researcher in 1999. Senior researcher of the Pressure and Vacuum Standard Section, Mechanical Metrology Division, National Metrology Institute of Japan, AIST in 2000. Section chief in 2011 to present. Visiting researcher of the National Institute of Standards Technology, USA from 2000 to 2001. Senior researcher of the R&D Technological Development Promotion Department, New Energy and Industrial Technology Development Organization from 2008 to 2009. Engages in research for pressure standard and pressure measurement. For this paper, was in charge of the organization of the research, R&D and calibration work for pressure in general, and drafting of the manuscript.Momoko KojimaCompleted the doctorate course at the Department of Energy Sciences, Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology in 2003. Doctor (Science). Joined AIST in 2003. Researcher of the Pressure and Vacuum Standard Section, Mechanical Metrology Division, National Metrology Institute of Japan, AIST. Engages in research for pressure standard and pressure measurement. For this paper, was in charge of the R&D and calibration work for gas pressure in general.Hiroaki KajikawaWithdrew from the doctorate course with the completion of course requirements at the Division of Physics and Astronomy, Graduate School of Science, Kyoto University in 2006. Joined AIST in 2006. Doctor (Science). Researcher of the Pressure and Vacuum Standard Section, Mechanical Metrology Division, National Metrology Institute of Japan, AIST. Engages in research for pressure standard and pressure measurement. For this paper, was in charge of the R&D and calibration work for hydraulic pressure in general.Discussions with Reviewers1 GeneralComment (Akira Ono, AIST)This paper describes an excellent research to improve the reliability in pressure measurements at industrial environments and to promote the international mutual recognition of pressure measurement results, by adeptly incorporating industrial digital pressure gauges with increased precision into the national standards system. Processes to identify elemental technologies by looking at the overall standards system for pressure measurements, and then creating a new pressure standards system by integrating the elemental technologies are well described. I think it is an appropriate Synthesiology paper.2 Cause of time-dependent change of digital pressure gaugeQuestion (Akira Ono)Figure 7 in the text shows change with time in the calibration results of digital pressure gauges used for the international comparison. While it may be difficult, since the degree of time-dependent change differs for individual pressure gauges, do you have any idea of what caused the time-dependent change? Answer (Tokihiko Kobata)The degrees of time-dependent change of the calibration value of the pressure gauge differ according to the types of gauges, the pressure range in which it is used, and the way it is used. In general, the time-dependent change of the calibration value of the pressure gauge is large in the gauge for high pressure, and small in the one for low pressure. In some cases, time-dependent change may not be so apparent. Also, as shown in Fig. 7, the amount of time-dependent change may be the function of applied pressure within a pressure gauge.Therefore, while I cannot generalize, one factor for time-dependent change of the calibration value is the effect of plastic deformation of the pressure receiver. If the pressure receiver undergoes complete elastic deformation, it deforms according to the amount of pressure applied, and returns to the original form when the pressure becomes zero. However, in actual pressure gauges, when the pressure is applied, the pressure receiver may undergo slight plastic deformation. Even though the deformation may be slight, it will not return to the original shape completely when the pressure is back to zero. When the process of applying pressure then returning to zero is repeated, the receiver shows larger deformation with the same pressure. In the example of Fig. 7, the calibration values of the six pressure gauges all change as the deformation of the receiver increases with time, even at the same applied pressure. The time-dependent change of these calibration values contains the effect of the plastic deformation as described.However, such changes are very small compared to the specified precision stated by the manufacturers, and it is hardly a problem in general use. However, in international comparison, the change must be corrected since a high level of measurement precision is demanded.3 Quantitative comparison of the conventional method and the new methodQuestion (Jun Hama, Energy Technology Research Institute, AIST)The calibration technology, where the high-precision digital pressure gauge is used as the transfer device, greatly contributes in reducing the works for the on-site pressure calibration, as a means to guarantee data reliability in product development and R&D.Please indicate the actual cases where there were reductions of number of days or cost of calibration compared to the conventional method, due to the easier, more efficient, and lower cost of on-site calibration.Answer (Tokihiko Kobata)As the actual case of efficiency, normally one to two weeks of calibration period is needed, including the transportation of the device under calibration, in the carry-in calibration for the digital pressure gauge, while in the various demonstration experiments conducted in Japan, the calibration could be done in two days by remote calibration in most cases. Also, in remote calibration, the duty hours of the person in charge of the calibration can be reduced, so the cost of labor can be reduced. However, currently,

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