Study of a New Fixed-Point System for Calibration of Short Secondary Platinum Resistance Thermometers

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Study of a New Fixed-Point System for Calibration of Short Secondary Platinum Resistance Thermometers (117.78 KB)

A new fixed-point system was developed to calibrate short (8 – 9 inches) secondary platinum resistance thermometers (PRTs) and industrial platinum resistance thermometers (IPRTs). The system includes a re-designed metal-cased fixed-point cell based on an existing metal-cased fixed-point cell which was recently developed to calibrate secondary PRTs (12 inches) at Fluke – Hart Scientific, and a maintenance furnace with a three-zone controller that provides excellent vertical temperature uniformity. The design and structure of the new fixed-point system is described in the paper. The system was tested with tin and zinc freezing-point cells by realizing the freezing plateau. The comparison testing was carried out with the standard size fused quartz glass shell tin and zinc cells. The testing results are presented, and the freezing plateau is fully evaluated and discussed in the paper.