ASTM E1750-23
(Guide)Standard Guide for Use of Water Triple Point Cells
Standard Guide for Use of Water Triple Point Cells
SIGNIFICANCE AND USE
4.1 This guide describes a procedure for placing a water triple-point cell in service and for using it as a reference temperature in thermometer calibration.
4.2 The reference temperature attained is that of a fundamental state of pure water, the equilibrium between coexisting solid, liquid, and vapor phases.
4.3 The cell is subject to qualification but not to calibration. The cell may be qualified as capable of representing the fundamental state (see 4.2) by comparison with a bank of similar qualified cells of known history, and it may be so qualified and the qualification documented by its manufacturer.
4.4 The temperature to be attributed to a qualified water triple-point cell is exactly 273.16 K on the ITS-90, unless corrected for isotopic composition (refer to Appendix X3).
4.5 Continued accuracy of a qualified cell depends upon sustained physical integrity. This may be verified by techniques described in Section 6.
4.6 The commercially available triple point of water cells described in this standard are capable of achieving an expanded uncertainty (k=2) of between ±0.1 mK and ±0.05 mK, depending upon the method of preparation. Specified measurement procedures shall be followed to achieve these levels of uncertainty.
4.7 Commercially-available triple point of water cells of unknown isotopic composition should be capable of achieving an expanded uncertainty (k=2) of no greater than 0.25 mK, depending upon the actual isotopic composition (3). These types of cells are acceptable for use at this larger value of uncertainty.
SCOPE
1.1 This guide covers the nature of two commercial water triple-point cells (types A and B, see Fig. 1) and provides a method for preparing the cell to realize the water triple-point and calibrate thermometers. The qualifications concerning preparation and the types of glass used for a cell are discussed. Tests for assuring the integrity of a qualified cell and of cells yet to be qualified are given. Precautions for handling the cell to avoid breakage are also described.
FIG. 1 Configurations of two commonly used triple point of water cells, Type A and Type B, with ice mantle prepared for measurement at the ice/water equilibrium temperature. The cells are used immersed in an ice bath or water bath controlled close to 0.01 °C (see 5.5)
1.2 The effect of hydrostatic pressure on the temperature of a water triple-point cell is discussed.
1.3 Procedures for adjusting the observed SPRT resistance readings for the effects of self-heating and hydrostatic pressure are described in Appendix X1 and Appendix X2.
1.4 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.
1.5 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.
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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: E1750 − 23
Standard Guide for
1
Use of Water Triple Point Cells
This standard is issued under the fixed designation E1750; 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
The triple point of water is an important thermometric fixed point as defined in the International
Temperature Scale of 1990 (ITS-90). The ITS-90 assigns a value of 273.16 K to the triple point of
water which was exactly equivalent to the thermodynamic temperature in the international System (SI)
2
of units at the time of the adoption of the ITS-90 (1, 2). The triple point of water is the temperature
to which the resistance ratios W(T) = R(T) ⁄R(273.16 K) of the standard platinum resistance
thermometer (SPRT) calibrations are referred to in the ITS-90.
The triple points of various materials (where three distinct phases, for example, their solid, liquid,
and vapor phases, coexist in a state of thermal equilibrium) have fixed pressures and temperatures and
are highly reproducible. Of the ITS-90 fixed points, six are triple points. The water triple point is one
of the most accurately realizable of the defining fixed points of the ITS-90; under the best of
conditions, it can be realized with an expanded uncertainty (k=2) of less than 60.00005 K. In
comparison, it is difficult to prepare and use an ice bath with an expanded uncertainty (k=2) of less
than 60.002 K (3).
1. Scope 1.5 This international standard was developed in accor-
dance with internationally recognized principles on standard-
1.1 This guide covers the nature of two commercial water
ization established in the Decision on Principles for the
triple-point cells (types A and B, see Fig. 1) and provides a
Development of International Standards, Guides and Recom-
method for preparing the cell to realize the water triple-point
mendations issued by the World Trade Organization Technical
and calibrate thermometers. The qualifications concerning
Barriers to Trade (TBT) Committee.
preparation and the types of glass used for a cell are discussed.
Tests for assuring the integrity of a qualified cell and of cells
2. Referenced Documents
yet to be qualified are given. Precautions for handling the cell
3
2.1 ASTM Standards:
to avoid breakage are also described.
E344 Terminology Relating to Thermometry and Hydrom-
1.2 The effect of hydrostatic pressure on the temperature of
etry
a water triple-point cell is discussed.
E1594 Guide for Expression of Temperature
1.3 Procedures for adjusting the observed SPRT resistance
3. Terminology
readings for the effects of self-heating and hydrostatic pressure
are described in Appendix X1 and Appendix X2.
3.1 Definitions—The definitions given in Terminology E344
apply to terms used in this guide.
1.4 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
3.2 Definitions of Terms Specific to This Standard:
responsibility of the user of this standard to establish appro-
3.2.1 inner melt, n—a thin continuous layer of water be-
priate safety, health, and environmental practices and deter-
tween the thermometer well and the ice mantle of a water
mine the applicability of regulatory limitations prior to use.
triple-point cell.
3.2.2 reference temperature, n—the temperature of a phase
1 equilibrium state of a pure substance at a specified pressure, for
This guide is under the jurisdiction of ASTM Committee E20 on Temperature
Measurement and is the direct responsibility of Subcommittee E20.07 on Funda- example, the assigned temperature of a fixed point.
mentals in Thermometry.
Current edition approved Nov. 1, 2023. Published December 2023. Originally
3
approved in 1995. Last previous edition approved in 2016 as E1750 – 10 (2016). For referenced ASTM standards, visit the ASTM website, www.astm.org, or
DOI: 10.1520/E1750-23. contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
2
The boldface numbers in parentheses refer to the list of references at the end of Standards volume information, refer to the standard’s Document Summary page on
this standard. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1
---------------------- Page: 1 ----------------------
E1750 − 23
FIG. 1 Configurations of two commonly used triple point of wa-
ter cells, Type A and Type B, with ice mantle prepared for mea-
surement at the ice/water equilibrium temp
...
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: E1750 − 10 (Reapproved 2016) E1750 − 23
Standard Guide for
1
Use of Water Triple Point Cells
This standard is issued under the fixed designation E1750; 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
The triple point of water is an important thermometric fixed point common to the definition of two
temperature scales of science and technology, the Kelvin Thermodynamic Temperature Scale (KTTS)
and the as defined in the International Temperature Scale of 1990 (ITS-90). The ITS-90 was designed
to be as close to the KTTS as the experimental data available at the time of the adoption of the ITS-90
would permit. The temperatures (T) on the KTTS are defined by assigning the value assigns a value
of 273.16 K to the triple point of water, thus defining the thermodynamic unit of temperature, kelvin
(K), as 1/273.16 of the thermodynamic temperature of the triple point of water water which was
exactly equivalent to the thermodynamic temperature in the international System (SI) of units at the
2
time of the adoption of the ITS-90 (1, 2). The triple point of water, one of the fixed points used to
define the ITS-90, water is the temperature to which the resistance ratios W(T) = R(T) ⁄R(273.16 K)
of the standard platinum resistance thermometer (SPRT) calibrations are referred.referred to in the
ITS-90.
The triple points of various materials (where three distinct phases, for example, their solid, liquid,
and vapor phases, coexist in a state of thermal equilibrium) have fixed pressures and temperatures and
are highly reproducible. Of the ITS-90 fixed points, six are triple points. The water triple point is one
of the most accurately realizable of the defining fixed points of the ITS-90; under the best of
conditions, it can be realized with an expanded uncertainty (k=2) of less than 60.00005 K. In
comparison, it is difficult to prepare and use an ice bath with an expanded uncertainty (k=2) of less
than 60.002 K (3).
1. Scope
1.1 This guide covers the nature of two commercial water triple-point cells (types A and B, see Fig. 1) and provides a method for
preparing the cell to realize the water triple-point and calibrate thermometers. The qualifications concerning preparation and the
types of glass used for a cell are discussed. Tests for assuring the integrity of a qualified cell and of cells yet to be qualified are
given. Precautions for handling the cell to avoid breakage are also described.
1.2 The effect of hydrostatic pressure on the temperature of a water triple-point cell is discussed.
1.3 Procedures for adjusting the observed SPRT resistance readings for the effects of self-heating and hydrostatic pressure are
described in Appendix X1 and Appendix X2.
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, 2016Nov. 1, 2023. Published May 2016December 2023. Originally approved in 1995. Last previous edition approved in 20102016 as
E1750 – 10.E1750 – 10 (2016). DOI: 10.1520/E1750-10R16.10.1520/E1750-23.
2
The boldface numbers in parentheses refer to the list of references at the end of this standard.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1
---------------------- Page: 1 ----------------------
E1750 − 23
FIG. 1 Configurations of two commonly used triple point of wa-
ter cells, Type A and Type B, with ice mantle prepared for mea-
surement at the ice/water equilibrium temperature. The cells are
used immersed in an ice bath or water bath controlled close to
0.01°C0.01 °C (see 5.45.5)
1.4 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 and healthsafety, health, and environmental practices and determine
the applicability of regulatory limitations prior to use.
1.5 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) C
...
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