AVALIAÇÃO METROLÓGICA DA ESTABILIDADE TERMOELÉTRICA DE TERMOPAR AUPT / METROLOGICAL ESTIMATION OF THERMOELECTRIC STABILITY IN AUPT THERMOCOUPLE

AUTOR(ES)
DATA DE PUBLICAÇÃO

2002

RESUMO

In 1990, with the adoption of the International Temperature Scale of 1990, the platinum/platinum-rhodium thermocouple was removed as the interpolation instrument between 630°C and 1064°C, due its low stability, in favor of the high temperature standard platinum resistance thermometer (HTSPRT) and the radiation thermometer. In this work, it is performed a practical investigation of the characteristics of a 99,999% purity gold-platinum thermocouple, concerning its thermoelectric stability and homogeneity of its thermoelements, questioning the possibility of its use as an alternative to the HTSPRT in measurement processes requiring high accuracy with lower costs. In this work, the test thermocouple was exposed to temperatures close to its upper limit (1000°C) for more than 1500 hours, being its stability and homogeneity evaluated as function of time, with aid of a silver fixed point cell from Inmetro, that is a temperature primary standard.

ASSUNTO(S)

ouro-platina thermometry thermocouple metrology termopar metrologia gold-platinum termometria

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