PERFORMANCE EVALUATION OF AN OPEN TIN CELL CONSTRUCTED AT INMETRO

R. N. Teixeira, R. da Silva

Abstract

The Inmetro Thermometry Laboratory uses fixed-points cells defined in the International Temperature Scale of 1990 (ITS-90) to calibrate thermocouples andstandard platinum resistance thermometers. In order to meetthis, the laboratory counts on reference fixed-point cellsfrom theArgon triple point (-189,3442°C) to the Copperfixed-point (1084,62°C). In a quest to improve its best measurement capability and to disseminate this, thelaboratory has been investing in the manufacture of its own primary standards. This process was started with water triple point cells, mercury triple point cells and pure noble metalthermocouples which have results validated through comparisons and are part of the laboratory standards regularly used in calibrations. The following step came to be an open metal cell. Zinc was chosen for being relatively inexpensive. The methodology and the corresponding results achieved were published in 2006 and 2008. Going on with this task, the laboratory constructed a Tin cell in 2010.All Inmetro cells are open, and they were compared to the three commercially available cells the laboratory previously had. The materials, methodology, uncertainty evaluation (impurity effect estimates) and results are discussed in the present paper.

Keywords

tin cell, fixed -point, thermometry

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IMEKO TC

TC4 - Measurement of Electrical Quantities

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