J. D. Brionizio, P. R. F. Santos, J. C. Andrade
The aim of this paper is to present the results of an interlaboratory comparison in temperature and relative humidity, among eleven laboratories, that was coordinated by the National Institute of Metrology, Quality and Technology (Inmetro, Brazil). As transfer standard, a thermo-hygrometer was used. The intercomparison was carried out in the range from 20 %rh to 90 %rh (at 20 ºC and 30 ºC) and from 20 ºC to 40 ºC. The performance of the intercomparison was judged by calculating the normalized error. Results from the majority of the labs agreed well with those of Inmetro.
XX IMEKO World Congress
· TC12
· 2012
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J. D. Brionizio, G. H. Bonnier, A. F. Orlando
Spherical heat source probes, which generate heat and monitor the temperature response with time, have been studied to measure thermal conductivity of different materials. However, for gases and liquids, the measurement of the thermal conductivity has to consider specific parameters. The aim of this paper is to model the physical phenomenon of a spherical device used to measure the thermal conductivity of liquids by means of the finite difference method, using commercial software, and then compare it to analytical equations. The influence of the thermal contact resistance in the process was...
XX IMEKO World Congress
· TC12
· 2012
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I. Yang, K. S. Gam, W. Joung, Y.-G. Kim
According to the ISO guide to the expression of uncertainty in measurement, the calibration process and its uncertainty evaluation should be expressed in terms of mathematical function(s) of input quantities. However, in practice, expressing measurement or calibration in a way that is fully compliant to the ISO guide might be unrealistic and requires a clear definition of the calibration process itself. Depending on the point of view on the calibration process, different modelling equation with various complexities can be written. In this paper, four different approaches are given to model...
XX IMEKO World Congress
· TC12
· 2012
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Jovan Bojkovski
This paper describes sources of uncertainties in the calibration of air temperature sensors. Air temperature sensors are calibrated within different calibration environments. Depending on the environment, typical sources of uncertainties are analyzed and evaluated. In total, three different air temperature sensors, two platinum resistance thermometers in combination with resistance bridge and one digital thermometer are calibrated from -7 °C to 70 °C and from -40 °C up to 100 °C, in two different calibration environments. The reference temperature was determined using thermistors and...
XX IMEKO World Congress
· TC12
· 2012
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Suherlan, Yong-Gyoo Kim
Three Si-SiC eutectic fixed-point cells have been constructed using electrically heated furnace for use in thermocouple thermometry. The first two cells were made from silicon powder mixed with carbon while the third was made from pure silicon. The first cell with a conventional graphite crucible was early broken during the preliminary test, so the result could not be recorded. The second cell with a modified graphite crucible, thicker and shorter than the previous one, was able to withstand until 36 melt-freeze cycles and was held above 1400 °C for about 143 h, but unfortunately this cell...
XX IMEKO World Congress
· TC12
· 2012
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Min Xie, Yuanqin Shao, Hanli Xu, Zhen Zhou, Le Chen
Principle of Raman-scattering based distributed optical fiber temperature sensor (DTS) system is introduced briefly in this paper. The reference temperature is an important factor to improve the measurement accuracy of the DTS system. An experimental method is presented to study the relationship between reference temperature and measurement accuracy. A temperature & humidity chamber is used to provide different reference temperatures. Experiment data show that the measurement deviation decreases when the reference temperature increases.
XX IMEKO World Congress
· TC12
· 2012
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Wukchul Joung, Kee Sool Gam, Inseok Yang, Yong-Gyoo Kim
Despite the importance of resistance bridges in thermometry, an accurate assessment of their uncertainty has not been investigated much. Among various uncertainty components, nonlinearity and ratio error have been of particular interest, and a Hamon-type resistance network known to be RBC (resistance bridge calibrator) is widely used to measure those uncertainties. However, due to finite temperature coefficients of base resistors in the RBC, the evaluated uncertainty of the resistance bridges under normal operating environment is in doubt. In this work, to accurately evaluate the uncertainty...
XX IMEKO World Congress
· TC12
· 2012
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K. S. Gam, I. Yang, U. C. Jeong, Y. G. Kim
In past 20 years KRISS prepared the fixed- points cells for the realization of the ITS-90. Home-made fixed-points was realized using the conventional methods and were estimated the uncertainties for the realization of the fixed points. The uncertainty factors from the impurities of samples, immersion depth of sensor, pressure variation of cells, and temperature gradient was analysed in detail and especially the uncertainty of the AC thermometer bridge arising from the noise factor and non-linearity was measured. The expanded uncertainty for the fixed-points with the coverage factor k = 2 was...
XX IMEKO World Congress
· TC12
· 2012
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Sung-Sin So, Hyun-Min Park, Yeun-Joon Jung
We set up the temperature - running period CM (Characteristic Modelling) of the noble metal thermocouples (S/B type). Using CM, we got the both thermocouples max error reduced, type S is 2.1 °C and type B is 1.8 °C which were 5.8 °C and 4.3 °C before using CM and the coefficients of determination in CM are 82.1 % and 72.5 %. It shows 85 % difference between CM and error less than 1.0 °C, especially in type B. So it is necessary to use CM to measure temperature accurately.
XX IMEKO World Congress
· TC12
· 2012
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Doaa Abd El-Gelil, M. G. Ahmed, Essam El-Din Mahmoud, Said Mazen
This paper describes construction and characterization of a dew/frost -point generator developed at national institute for standards. It is intended to operate in the range from -50 °C to 0 °C. The air flows through a saturator controlled by a regulated flow meter. The reference dew/frost -point temperature was measured by Standard Platinum Resistance Thermometer (SPRT) connected to a resistance bridge. A comparative study between the saturator temperature of the new generator measured by SPRT and the dew/frost-point temperature of a calibrated chilledmirror hygrometer was conducted. It...
XX IMEKO World Congress
· TC12
· 2012
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