Evaluation of Some High-Temperature Platinum Resistance Thermometers

Evans, J. P.

doi:10.6028/jres.089.020

Cited by 16 publications

(21 citation statements)

References 22 publications

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“…One possibility may be to exploit the sensitivity of the diode resistance to a dc bias voltage. For example, several papers report that a change in a bias voltage applied to the resistance measurement circuit affects the reading [43][44][45]. However, interpretation of such a change in resistance is complicated because the bias voltage is typically applied via the furnace heater.…”

Section: Insulation Breakdown Effectsmentioning

confidence: 99%

Uncertainties in the SPRT Subranges of ITS-90: Topics for Further Research

White¹,

Ballico

Campo

et al. 2010

Int J Thermophys

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The CCT has completed the guide summarizing the uncertainties in the realization of the SPRT subranges of ITS-90 between the triple point of neon (24.5561 K) and the freezing point of silver (961.78 • C). This article identifies aspects of standard platinum resistance thermometry where either data or models are lacking and further research is required. In the calibration of SPRTs, the two main concerns are the need for data on liquidus slopes for the different impurities in the fixed points and improved understanding of the impact of the thermal environment of the fixed point on the realized temperature. In the use of SPRTs, the two largest sources of uncertainty are Types 1 and 3 non-uniqueness and oxidation. The causes of Type 3 non-uniqueness are not yet understood, especially at low temperatures, and there is a paucity of data for the high-temperature subranges. In respect of oxidation, there is a need for validation of the models developed in the 1980s, especially in light of the reduced partial pressure of oxygen used in modern SPRTs. A range of other effects including vacancy effects in SPRTs, isotopic effects in fixed points, and improved statistical methods are discussed.

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Section: Insulation Breakdown Effectsmentioning

confidence: 99%

Uncertainties in the SPRT Subranges of ITS-90: Topics for Further Research

White¹,

Ballico

Campo

et al. 2010

Int J Thermophys

View full text Add to dashboard Cite

show abstract

“…to uncertainties in measured temperatures [1][2][3][4][5][6][7][8][9][10][11][12]. Since the effect shunts the sensing resistance, it is currently managed by using low sensing resistances.…”

mentioning

confidence: 99%

A Schottky-Diode Model of the Nonlinear Insulation Resistance Effects in SPRTs—Part 1: Theory

White¹,

Arai

Bittar³

et al. 2007

Int J Thermophys

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The decreasing insulation resistance of standard platinum resistance thermometers (SPRT) above about 850 • C makes a major contribution to uncertainties in measured temperatures. In principle, the insulation breakdown ought to be easily modeled as a temperature-dependent shunt resistance depending principally on the insulator materials and dimensions. However, the phenomenon exhibits a complex nonlinear behavior that, to date, has defied explanation. The lack of an explanation is a major obstacle to improvements in SPRT design and to assessments of uncertainty caused by the insulation breakdown. This article suggests that the nonlinear effects are due to metal-semiconductor diodes, also known as Schottky-barrier or point-contact diodes, formed at the points of contact between the fused-silica insulators and the platinum of the SPRT sensing element and lead wires. The article presents an overview of the theory underlying Schottky diodes, shows that this model qualitatively explains the observations, and suggests practical experiments to verify the model.

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“…Various interpretations and models of the leakage effect have been proposed [23][24][25][26]; however, applying these models requires some destruction of the HT-SPRT upon its characterization. Since the leakage effect will differ among individual HT-SPRTs, significantly due to the contact state between the metal and the insulator within the HT-SPRT, it is very difficult to evaluate its magnitude for actual thermometers in operation.…”

Section: Leakage Effectmentioning

confidence: 99%

Comparison Measurements for the Development of High-Temperature Platinum Resistance Scale

et al. 2010

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This paper describes measurements aimed to develop the high-temperature scale for high-temperature standard platinum resistance thermometers (HT-SPRTs). A furnace designed to facilitate comparison of a radiation thermometer with a HT-SPRT was developed for this work. The measurement uncertainty of the comparison is first reported, and then the comparison results for eight HT-SPRTs for temperatures from 660 • C up to 1040 • C are presented. Two different methods were adopted to analyze the comparison results. Upon discussion of the comparison results and adopting the second method to analyze the data, a correction term to the reference function of HT-SPRTs for temperatures above the current high-temperature limit, the Ag freezing point (961.78 • C), is suggested, as a preliminary result upon seeking the possibility to propose the extension of the platinum resistance thermometer scale. The two irregular cases for discussion of the criteria for interpolating HT-SPRTs of the current International Temperature Scale of 1990 (ITS-90) are also discussed.

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Evaluation of Some High-Temperature Platinum Resistance Thermometers

Cited by 16 publications

References 22 publications

Uncertainties in the SPRT Subranges of ITS-90: Topics for Further Research

Uncertainties in the SPRT Subranges of ITS-90: Topics for Further Research

A Schottky-Diode Model of the Nonlinear Insulation Resistance Effects in SPRTs—Part 1: Theory

Comparison Measurements for the Development of High-Temperature Platinum Resistance Scale

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