Integrated self-validating thermocouples with a reference temperature up to 1329 °C

Declan Tucker, Aurik Andreu, Claire Elliott, Trevor Ford, Marius Neagu, Graham Machin, Jonathan Pearce

Research output: Contribution to journalArticle

Abstract

Thermoelectric instability, or calibration drift, is a major problem for users of thermocouples at high temperature. NPL, in collaboration with CCPI Europe, AFRC and ICPE-CA/BRML-INM has designed, made and industrially tested Type S thermocouples with integrated temperature fixed-point cells. These in situ, self-validating thermocouples (denoted 'inseva') have the same external dimensions as conventional industrial thermocouples (the recrystallised alumina sheath has an outer diameter 7 of mm). The device can be used to detect the melting and/or freezing temperature of the integrated temperature fixed-point ingot, which enables a self-validation to be performed whilst in situ. During the testing, three different reference ingots were used in the cells, namely: copper (1084 °C), cobalt-carbon (1324 °C) and nickel-carbon (1329 °C). The metrological performance for two iterations of the design are presented, with an emphasis on the ability of the inseva thermocouples to indicate their own thermoelectric stability. A measurement uncertainty budget is also given for the case of a Ni–C inseva thermocouple. This paper demonstrates that inseva thermocouples can be successfully validated during industrial processes through the observation of the melting plateau, as well as their robustness over time in industrial conditions. A key finding is that the Ni–C eutectic alloy is much more robust than the Co–C eutectic alloy for the used type of graphite crucible, making the Ni–C inseva thermocouple more suitable for industrial applications, and a good alternative.
LanguageEnglish
Article number105002
Number of pages9
JournalMeasurement Science and Technology
Volume29
Issue number10
DOIs
Publication statusPublished - 31 Aug 2018

Fingerprint

thermocouples
Thermocouples
Melting
Carbon
Fixed point
Cobalt
Measurement Uncertainty
Alumina
Graphite
Cell
Freezing
Nickel
Industrial Application
Copper
eutectic alloys
Temperature
temperature
ingots
Calibration
Ingots

Keywords

  • calibration drift
  • thermocouples
  • thermoelectric instability
  • industrial processes
  • high temperature processes

Cite this

Tucker, Declan ; Andreu, Aurik ; Elliott, Claire ; Ford, Trevor ; Neagu, Marius ; Machin, Graham ; Pearce, Jonathan. / Integrated self-validating thermocouples with a reference temperature up to 1329 °C. In: Measurement Science and Technology . 2018 ; Vol. 29, No. 10.
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abstract = "Thermoelectric instability, or calibration drift, is a major problem for users of thermocouples at high temperature. NPL, in collaboration with CCPI Europe, AFRC and ICPE-CA/BRML-INM has designed, made and industrially tested Type S thermocouples with integrated temperature fixed-point cells. These in situ, self-validating thermocouples (denoted 'inseva') have the same external dimensions as conventional industrial thermocouples (the recrystallised alumina sheath has an outer diameter 7 of mm). The device can be used to detect the melting and/or freezing temperature of the integrated temperature fixed-point ingot, which enables a self-validation to be performed whilst in situ. During the testing, three different reference ingots were used in the cells, namely: copper (1084 °C), cobalt-carbon (1324 °C) and nickel-carbon (1329 °C). The metrological performance for two iterations of the design are presented, with an emphasis on the ability of the inseva thermocouples to indicate their own thermoelectric stability. A measurement uncertainty budget is also given for the case of a Ni–C inseva thermocouple. This paper demonstrates that inseva thermocouples can be successfully validated during industrial processes through the observation of the melting plateau, as well as their robustness over time in industrial conditions. A key finding is that the Ni–C eutectic alloy is much more robust than the Co–C eutectic alloy for the used type of graphite crucible, making the Ni–C inseva thermocouple more suitable for industrial applications, and a good alternative.",
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Integrated self-validating thermocouples with a reference temperature up to 1329 °C. / Tucker, Declan; Andreu, Aurik; Elliott, Claire; Ford, Trevor; Neagu, Marius; Machin, Graham; Pearce, Jonathan.

In: Measurement Science and Technology , Vol. 29, No. 10, 105002, 31.08.2018.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Integrated self-validating thermocouples with a reference temperature up to 1329 °C

AU - Tucker, Declan

AU - Andreu, Aurik

AU - Elliott, Claire

AU - Ford, Trevor

AU - Neagu, Marius

AU - Machin, Graham

AU - Pearce, Jonathan

N1 - This article is subject to Crown Copyright (c) and is therefore made available under a UK Open Government Licence (OGL).

PY - 2018/8/31

Y1 - 2018/8/31

N2 - Thermoelectric instability, or calibration drift, is a major problem for users of thermocouples at high temperature. NPL, in collaboration with CCPI Europe, AFRC and ICPE-CA/BRML-INM has designed, made and industrially tested Type S thermocouples with integrated temperature fixed-point cells. These in situ, self-validating thermocouples (denoted 'inseva') have the same external dimensions as conventional industrial thermocouples (the recrystallised alumina sheath has an outer diameter 7 of mm). The device can be used to detect the melting and/or freezing temperature of the integrated temperature fixed-point ingot, which enables a self-validation to be performed whilst in situ. During the testing, three different reference ingots were used in the cells, namely: copper (1084 °C), cobalt-carbon (1324 °C) and nickel-carbon (1329 °C). The metrological performance for two iterations of the design are presented, with an emphasis on the ability of the inseva thermocouples to indicate their own thermoelectric stability. A measurement uncertainty budget is also given for the case of a Ni–C inseva thermocouple. This paper demonstrates that inseva thermocouples can be successfully validated during industrial processes through the observation of the melting plateau, as well as their robustness over time in industrial conditions. A key finding is that the Ni–C eutectic alloy is much more robust than the Co–C eutectic alloy for the used type of graphite crucible, making the Ni–C inseva thermocouple more suitable for industrial applications, and a good alternative.

AB - Thermoelectric instability, or calibration drift, is a major problem for users of thermocouples at high temperature. NPL, in collaboration with CCPI Europe, AFRC and ICPE-CA/BRML-INM has designed, made and industrially tested Type S thermocouples with integrated temperature fixed-point cells. These in situ, self-validating thermocouples (denoted 'inseva') have the same external dimensions as conventional industrial thermocouples (the recrystallised alumina sheath has an outer diameter 7 of mm). The device can be used to detect the melting and/or freezing temperature of the integrated temperature fixed-point ingot, which enables a self-validation to be performed whilst in situ. During the testing, three different reference ingots were used in the cells, namely: copper (1084 °C), cobalt-carbon (1324 °C) and nickel-carbon (1329 °C). The metrological performance for two iterations of the design are presented, with an emphasis on the ability of the inseva thermocouples to indicate their own thermoelectric stability. A measurement uncertainty budget is also given for the case of a Ni–C inseva thermocouple. This paper demonstrates that inseva thermocouples can be successfully validated during industrial processes through the observation of the melting plateau, as well as their robustness over time in industrial conditions. A key finding is that the Ni–C eutectic alloy is much more robust than the Co–C eutectic alloy for the used type of graphite crucible, making the Ni–C inseva thermocouple more suitable for industrial applications, and a good alternative.

KW - calibration drift

KW - thermocouples

KW - thermoelectric instability

KW - industrial processes

KW - high temperature processes

U2 - 10.1088/1361-6501/aad8a8

DO - 10.1088/1361-6501/aad8a8

M3 - Article

VL - 29

JO - Measurement Science and Technology

T2 - Measurement Science and Technology

JF - Measurement Science and Technology

SN - 0957-0233

IS - 10

M1 - 105002

ER -