ASTM E1502-22
(Guide)Standard Guide for Use of Fixed-Point Cells for Reference Temperatures
Standard Guide for Use of Fixed-Point Cells for Reference Temperatures
SIGNIFICANCE AND USE
5.1 A pure material has a well defined phase transition behavior, and the phase transition plateau, a characteristic of the material, can serve as a reproducible reference temperature for the calibration of thermometers. The melting or freezing points of some highly purified metals have been designated as defining fixed points on ITS-90. The fixed points of other materials have been determined carefully enough that they can serve as secondary reference points (see Tables 1 and 2). This guide presents information on the phase transition process as it relates to establishing a reference temperature. (A) Defining fixed point for ITS-90.(B) Realized as melting point.(C) Based on recommendation of International Bureau of Weights and Measures (BIPM) Working Group 2 of the Comité Consultatif de Thermométrie (CCT-WG2); published as: Bedford, R. E., Bonnier, G., Maas, H., and Pavese, F., "Recommended Values of Temperature on the International Temperature Scale of 1990 for a Selected Set of Secondary Reference Points", Metrologia, Vol 33, 1996, pp. 133. DOI: 10.1088/0026-1394/33/2/3. (A) Values for cells of good design, construction, and material purity used with careful technique. Cells of lesser quality may not approach these values.(B) Realized as melting point.
5.2 Fixed-point cells provide users with a means of realizing melting and freezing points. If the cells are appropriately designed and constructed, if they contain material of adequate purity, and if they are properly used, they can establish reference temperatures with uncertainties of a few millikelvins or less. This guide describes some of the design and use considerations.
5.3 Fixed-point cells can be constructed and operated less stringently than required for millikelvin uncertainty, yet still provide reliable, durable, easy-to-use fixed points for a variety of industrial calibration and heat treatment purposes. For example, any freezing-point cell can be operated, often advantageously, as a melting-po...
SCOPE
1.1 This guide describes the essential features of fixed-point cells and auxiliary apparatus, and the techniques required to realize fixed points in the temperature range from 29 °C to 1085 °C.3
1.2 Design and construction requirements of fixed-point cells are not addressed in this guide. Typical examples are given in Figs. 1 and 2.
FIG. 1 Examples of Fixed-Point Cells
FIG. 2 Example of Fixed-Point Furnace
Note 1: This example shows an insulated furnace body and two alternative types of furnace cores. The core on the left is a three-zone shielded type. The core on the right employs a heat pipe to reduce temperature gradients.
1.3 This guide is intended to describe good practice and establish uniform procedures for the realization of fixed points.
1.4 This guide emphasizes principles. The emphasis on principles is intended to aid the user in evaluating cells, in improving technique for using cells, and in establishing procedures for specific applications.
1.5 For the purposes of this guide, the use of fixed-point cells for the accurate calibration of thermometers is restricted to immersion-type thermometers that, when inserted into the reentrant well of the cell, (1) indicate the temperature only of the isothermal region of the well, and (2) do not significantly alter the temperature of the isothermal region of the well by heat transfer.
1.6 This guide does not address all of the details of thermometer calibration.
1.7 This guide is intended to complement special operating instructions supplied by manufacturers of fixed-point apparatus.
1.8 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.9 The following hazard caveat pertains only to the test method portion, Section 7, of this guide. This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of th...
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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: E1502 − 22
Standard Guide for
1
Use of Fixed-Point Cells for Reference Temperatures
This standard is issued under the fixed designation E1502; 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.
INTRODUCTION
Duringmeltingandfreezing,purematerialtransformsfromthesolidstatetotheliquidstateorfrom
the liquid state to the solid state at a constant temperature. That constant temperature is referred to as
a fixed point. Fixed points approached in the melting direction are referred to as melting points and
fixed points approached in the freezing direction are referred to as freezing points. Fixed points of
highly purified materials can serve as reference temperatures, and in fact, the International
2
Temperature Scale of 1990 (ITS-90) relies on the melting and freezing points of some highly purified
metals as defining fixed points. Fixed points can be realized in commercially available systems
incorporating fixed-point cells. When the cells are properly made and used, they establish useful
reference temperatures for the calibration of thermometers and for other industrial and laboratory
3
purposes; with care, these fixed points can be realized with an uncertainty of a few millikelvins or
less.
1. Scope to immersion-type thermometers that, when inserted into the
reentrant well of the cell, (1) indicate the temperature only of
1.1 This guide describes the essential features of fixed-point
the isothermal region of the well, and (2) do not significantly
cells and auxiliary apparatus, and the techniques required to
alter the temperature of the isothermal region of the well by
realize fixed points in the temperature range from 29 °C to
3 heat transfer.
1085 °C.
1.6 This guide does not address all of the details of
1.2 Design and construction requirements of fixed-point
thermometer calibration.
cells are not addressed in this guide. Typical examples are
given in Figs. 1 and 2.
1.7 This guide is intended to complement special operating
instructions supplied by manufacturers of fixed-point appara-
1.3 This guide is intended to describe good practice and
tus.
establish uniform procedures for the realization of fixed points.
1.8 The values stated in SI units are to be regarded as
1.4 This guide emphasizes principles. The emphasis on
standard. No other units of measurement are included in this
principles is intended to aid the user in evaluating cells, in
standard.
improving technique for using cells, and in establishing pro-
cedures for specific applications.
1.9 The following hazard caveat pertains only to the test
methodportion,Section7,ofthisguide.Thisstandarddoesnot
1.5 For the purposes of this guide, the use of fixed-point
purport to address all of the safety concerns, if any, associated
cells for the accurate calibration of thermometers is restricted
with its use. It is the responsibility of the user of this standard
1 to establish appropriate safety, health, and environmental
This guide is under the jurisdiction of ASTM Committee E20 on Temperature
Measurement and is the direct responsibility of Subcommittee E20.07 on Funda- practices and determine the applicability of regulatory limita-
mentals in Thermometry.
tions prior to use.
CurrenteditionapprovedJune1,2022.PublishedJuly2022.Originallyapproved
1.10 This international standard was developed in accor-
in 1992. Last previous edition approved in 2016 as E1502 – 16. DOI: 10.1520/
dance with internationally recognized principles on standard-
E1502-22.
2
Preston-Thomas, H., “The International Temperature Scale of 1990 (ITS-90),”
ization established in the Decision on Principles for the
Metrologia, Vol 27, No. 1, 1990, pp. 3–10. For errata see ibid, Vol 27, No. 2, 1990,
Development of International Standards, Guides and Recom-
p. 107.
3 mendations issued by the World Trade Organization Technical
In this guide, temperature intervals are expressed in kelvins (K) and millikel-
vins (mK). Values of temperature are expressed in degrees Celsius (°C), ITS-90. Barriers to Trade (TBT) Committee.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1
---------------------- Page: 1 ----------------------
E1502 − 22
3.2.2 fixed-point cell, n—a device that contains and protects
a sample of reference material in such a manner that the phase
transition of the material can establish a reference temperature.
3.2.3 freeze, n—an experiment or test run conducted with a
...
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: E1502 − 16 E1502 − 22
Standard Guide for
1
Use of Fixed-Point Cells for Reference Temperatures
This standard is issued under the fixed designation E1502; 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.
INTRODUCTION
During melting and freezing, pure material transforms from the solid state to the liquid state or from
the liquid state to the solid state at a constant temperature. That constant temperature is referred to as
a fixed point. Fixed points approached in the melting direction are referred to as melting points and
fixed points approached in the freezing direction are referred to as freezing points. Fixed points of
highly purified materials can serve as reference temperatures, and in fact, the International
2
Temperature Scale of 1990 (ITS-90) relies on the melting and freezing points of some highly purified
metals as defining fixed points. Fixed points can be realized in commercially available systems
incorporating fixed-point cells. When the cells are properly made and used, they establish useful
reference temperatures for the calibration of thermometers and for other industrial and laboratory
3
purposes; with care, these fixed points can be realized with an uncertainty of a few millikelvins or
less.
1. Scope
1.1 This guide describes the essential features of fixed-point cells and auxiliary apparatus, and the techniques required to realize
3
fixed points in the temperature range from 2929 °C to 1085°C.1085 °C.
1.2 Design and construction requirements of fixed-point cells are not addressed in this guide. Typical examples are given in Figs.
1 and 2.
1.3 This guide is intended to describe good practice and establish uniform procedures for the realization of fixed points.
1.4 This guide emphasizes principles. The emphasis on principles is intended to aid the user in evaluating cells, in improving
technique for using cells, and in establishing procedures for specific applications.
1.5 For the purposes of this guide, the use of fixed-point cells for the accurate calibration of thermometers is restricted to
immersion-type thermometers that, when inserted into the reentrant well of the cell, (1) indicate the temperature only of the
isothermal region of the well, and (2) do not significantly alter the temperature of the isothermal region of the well by heat transfer.
1
This guide is under the jurisdiction of ASTM Committee E20 on Temperature Measurement and is the direct responsibility of Subcommittee E20.07 on Fundamentals
in Thermometry.
Current edition approved May 1, 2016June 1, 2022. Published September 2016July 2022. Originally approved in 1992. Last previous edition approved in 20102016 as
E1502 – 10.E1502 – 16. DOI: 10.1520/E1502-16. 10.1520/E1502-22.
2
Preston-Thomas, H., “The International Temperature Scale of 1990 (ITS-90),” Metrologia, Vol 27, No. 1, 1990, pp. 3–10. For errata see ibid, Vol 27, No. 2, 1990, p.
107.
3
In this guide, temperature intervals are expressed in kelvins (K) and millikelvins (mK). Values of temperature are expressed in degrees Celsius (°C), ITS-90.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1
---------------------- Page: 1 ----------------------
E1502 − 22
FIG. 1 Examples of Fixed-Point Cells
1.6 This guide does not address all of the details of thermometer calibration.
1.7 This guide is intended to complement special operating instructions supplied by manufacturers of fixed-point apparatus.
1.8 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.9 The following hazard caveat pertains only to the test method portion, Section 7, of this guide. 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 safety, health, and healthenvironmental practices and determine the applicability of regulatory limitations prior
to use.
1.10 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 Tra
...
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