ASTM E2730-22

Standard Guide for Calibration and Use of Thermocouple Reference Junction Probes in Evaluation of Electronic Reference Junction Compensation Circuits

SIGNIFICANCE AND USE
5.1 Many electronic instruments that are designed to be used with thermocouples use some method of reference junction compensation. In many industrial applications it may be impractical to use a physical ice bath as a temperature reference in a thermocouple circuit. The instrument must therefore be able to measure the temperature at the point of electrical connection of the thermocouple and either add or subtract voltage to give a corrected equivalent of what that thermocouple would indicate had there physically been 0 °C reference junctions present in the circuit. There are two types of instruments that generally apply these techniques: electronic thermometer readouts that use a thermocouple as the sensor, and calibrators designed to calibrate these digital thermometer readouts. Additionally, the probe and circuit described in this guide can be used with a voltmeter to emulate a thermometer or a voltage source to calibrate temperature-indicating instrumentation. In all cases the probe must be calibrated if traceability or an uncertainty analysis, or both, is required.
SCOPE
1.1 This guide covers methods of calibration and use of thermocouple reference junction probes (cold junction compensation probes) in the evaluation of electronic reference junction compensation circuits. Their use with instruments that measure only voltage is also covered.  
1.2 The values stated in SI units are to be regarded as standard. The values given in parentheses after SI units are provided for information only and are not considered standard.  
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Published
• Publication Date: 30-Apr-2022
• ICS: 17.200.20 - Temperature-measuring instruments
• Technical Committee: E20 - Temperature Measurement
• Drafting Committee: E20.14 - Thermocouples - Testing

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: E2730 − 22 An American National Standard
Standard Guide for
Calibration and Use of Thermocouple Reference Junction
Probes in Evaluation of Electronic Reference Junction
1
Compensation Circuits
This standard is issued under the fixed designation E2730; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope E1129/E1129M Specification for Thermocouple Connectors
E1684/E1684M Specification for Miniature Thermocouple
1.1 This guide covers methods of calibration and use of
Connectors
thermocouple reference junction probes (cold junction com-
E1750 Guide for Use of Water Triple Point Cells
pensation probes) in the evaluation of electronic reference
E2623 Practice for Reporting Thermometer Calibrations
junction compensation circuits.Their use with instruments that
measure only voltage is also covered. 2.2 Other References:
NIST Monograph 175 Temperature-Electromotive Force
1.2 The values stated in SI units are to be regarded as
Reference Functions and Tables for the Letter-Designated
standard. The values given in parentheses after SI units are
3
Thermocouple Types Based on the ITS-90
provided for information only and are not considered standard.
BIPM JCGM 100:2008 Evaluation of Measurement Data—
1.3 This standard does not purport to address all of the 4
Guide to the Expression of Uncertainty in Measurement
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro-
3. Terminology
priate safety, health, and environmental practices and deter-
3.1 Definitions:
mine the applicability of regulatory limitations prior to use.
3.1.1 ThedefinitionsgiveninTerminologyE344shallapply
1.4 This international standard was developed in accor-
to this guide.
dance with internationally recognized principles on standard-
3.2 Definitions of Terms Specific to This Standard:
ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom-
3.2.1 correction, n—an offset value added to the result of a
mendations issued by the World Trade Organization Technical
measurement to obtain a correct result.
Barriers to Trade (TBT) Committee.
NOTE 1—This definition is from Test Method E220.
2. Referenced Documents
3.2.2 referencejunctioncompensation,n—theelectricalcor-
2
2.1 ASTM Standards: rection of the indication of a thermocouple such that the
E220 Test Method for Calibration of Thermocouples By corrected indication is equivalent to the emf or temperature the
Comparison Techniques instrument would indicate if the reference junctions were
E230/E230M Specification for Temperature-Electromotive physically maintained at 0 °C.
Force (emf) Tables for Standardized Thermocouples
3.2.3 reference junction probe, n—a probe constructed from
E344 Terminology Relating to Thermometry and Hydrom-
thermocouple materials and high purity copper wire for the
etry
purposeofservingasthereferencejunctionforathermocouple
E563 Practice for Preparation and Use of an Ice-Point Bath
assembly;referencejunctionprobesmaybeconstructedaspart
as a Reference Temperature
of the measuring probe or they can be manufactured separately
and later attached to thermocouple sensors via plugs or other
1
connection types.
This guide is under the jurisdiction of ASTM Committee E20 on Temperature
Measurement and is the direct responsibility of Subcommittee E20.14 on Thermo-
3.2.4 UUT, n—Unit Under Test.
couples - Testing.
Current edition approved May 1, 2022. Published May 2022. Originally
approved in 2010. Last previous edition approved in 2021 as E2730 – 21.
DOI:10.1520/E2730-22.
2 3
For referenced ASTM standards, visit the ASTM website, www.astm.org, or Available from National Institute of Standards and Technology (NIST), 100
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Bureau Dr., Stop 1070, Gaithersburg, MD 20899-1070, USA, http://www.nist.gov.
4
Standards volume information, refer to the standard’s Document Summary page on Available from Pavillon de Breteuil, F-92312 Sèvres Cedex, FRANCE,
the ASTM website. https://www.bipm.org/.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

---------------------- Page: 1 ----------------------
E2730 − 22
4. Summary of Guide 6. Reagents
6.1 Laboratory or commercially produced distilled water is
4.1 Calibration of a Reference Junction Probe (RJP) con-
required to creat
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: E2730 − 21 E2730 − 22 An American National Standard
Standard Guide for
Calibration and Use of Thermocouple Reference Junction
Probes in Evaluation of Electronic Reference Junction
1
Compensation Circuits
This standard is issued under the fixed designation E2730; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This guide covers methods of calibration and use of thermocouple reference junction probes (cold junction compensation
probes) in the evaluation of electronic reference junction compensation circuits. Their use with instruments that measure only
voltage is also covered.
1.2 The values stated in SI units are to be regarded as standard. The values given in parentheses after SI units are provided for
information only and are not considered standard.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of
regulatory limitations prior to use.
1.4 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2
2.1 ASTM Standards:
E220 Test Method for Calibration of Thermocouples By Comparison Techniques
E230/E230M Specification for Temperature-Electromotive Force (emf) Tables for Standardized Thermocouples
E344 Terminology Relating to Thermometry and Hydrometry
E563 Practice for Preparation and Use of an Ice-Point Bath as a Reference Temperature
E1129/E1129M Specification for Thermocouple Connectors
E1684/E1684M Specification for Miniature Thermocouple Connectors
E1750 Guide for Use of Water Triple Point Cells
E2623 Practice for Reporting Thermometer Calibrations
2.2 Other References:
NIST Monograph 175 Temperature-Electromotive Force Reference Functions and Tables for the Letter-Designated Thermo-
3
couple Types Based on the ITS-90
1
This guide is under the jurisdiction of ASTM Committee E20 on Temperature Measurement and is the direct responsibility of Subcommittee E20.14 on Thermocouples
- Testing.
Current edition approved May 1, 2021May 1, 2022. Published July 2021May 2022. Originally approved in 2010. Last previous edition approved in 20152021 as
ε2
E2730 – 10 (2015)E2730 – 21. . DOI:10.1520/E2730-21. DOI:10.1520/E2730-22.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
3
Available from National Institute of Standards and Technology (NIST), 100 Bureau Dr., Stop 1070, Gaithersburg, MD 20899-1070, USA, http://www.nist.gov.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

---------------------- Page: 1 ----------------------
E2730 − 22
4
BIPM JCGM 100:2008 Evaluation of Measurement Data—Guide to the Expression of Uncertainty in Measurement
3. Terminology
3.1 Definitions:
3.1.1 The definitions given in Terminology E344 shall apply to this guide.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 correction, n—an offset value added to the result of a measurement to obtain a correct result.
NOTE 1—This definition is from Test Method E220.
3.2.2 reference junction compensation, n—the electrical correction of the indication of a thermocouple such that the corrected
indication is equivalent to the emf or temperature the instrument would indicate if the reference junctions were physically
maintained at 0 °C.
3.2.3 reference junction probe, n—a probe constructed from thermocouple materials and high purity copper wire for the purpose
of serving as the reference junction for a thermocouple assembly; reference junction probes may be constructed as part of the
measuring probe or they can be manufactured separately and later attached to thermocouple sensors via plugs or other connection
types.
3.2.4 UUT, n—Unit Under Test.
4. Summary of Guide
4.1 Calibration of a Re
...