ASTM E563-22

Standard Practice for Preparation and Use of an Ice-Point Bath as a Reference Temperature

SIGNIFICANCE AND USE
5.1 This practice is adequate for use with other ASTM standards that specify the ice point as a reference. It is also intended to be adequate for most other ice-point reference purposes.  
5.2 The ice point is a common practical industrial reference point of thermometry. The ice point is relatively simple to realize and provides a readily available natural fixed-point reference temperature.  
5.3 Use in Resistance Thermometry:  
5.3.1 The ice point was a defining fixed point on practical temperature scales prior to 1960.  
5.3.2 The ITS-90 defines W(T90) = R(T90)/R(273.16 K), the measured resistance ratio of a Standard Platinum Resistance Thermometer (SPRT), in reference to the water triple point, not the ice point (1).3 In many instances, where the water triple point is not available, or when the accuracy obtainable with the water triple point is not required, reference to a properly established and maintained ice-point reference is used. For industrial-quality resistance thermometers, the resistance value is determined for 0 °C, and an uncertainty that is appropriate for the quality of the ice-point realization is assigned.  
5.4 Use in Thermoelectric Thermometry:  
5.4.1 In thermoelectric thermometry, the ice point is ordinarily used as the reference temperature (2).  
5.4.2 Adequate thermoelectric reference requires that thermocouple junctions be well-coupled thermally to the bath, electrically isolated from each other and from the bath, and adequately immersed to avoid perturbing the reference-junction temperatures by radiation and longitudinal conduction of heat along the thermoelements (3 and 4).  
5.5 Use in Liquid-in-Glass Thermometry:  
5.5.1 In liquid-in-glass thermometry, the ice point is ordinarily used as the reference temperature (5).  
5.5.2 The periodic recalibration of a liquid-in-glass thermometer at the ice point provides a reliable indication of the effect of gradual relaxation of residual mechanical strains in the glass that have a...
SCOPE
1.1 This practice covers a method of preparing, maintaining, and using a temperature reference bath of a mixture of shaved ice and water, saturated with air at a pressure of 101 325 Pa (1 atm).  
1.2 An industrial practice for relating values referenced to the ice point and to the water triple point on the ITS-90 is included.  
1.3 Methods to promote uniformity of bath temperature by mechanical stirring or agitation are not described in detail.  
1.4 Methods of approximating the ice point, as by thermostatically-controlled refrigeration, are not covered by this practice.  
1.5 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.  
1.6 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: 71.040.20 - Laboratory ware and related apparatus
• Technical Committee: E20 - Temperature Measurement
• Drafting Committee: E20.07 - Fundamentals in Thermometry

Relations

• Refers: ASTM E344-23 - Terminology Relating to Thermometry and Hydrometry
• Effective Date: 01-Dec-2023
• Refers: ASTM E344-19 - Terminology Relating to Thermometry and Hydrometry
• Effective Date: 01-Sep-2019
• Refers: ASTM E344-18 - Terminology Relating to Thermometry and Hydrometry
• Effective Date: 01-Apr-2018
• Refers: ASTM E344-16 - Terminology Relating to Thermometry and Hydrometry
• Effective Date: 01-Nov-2016
• Refers: ASTM E344-13 - Terminology Relating to Thermometry and Hydrometry
• Effective Date: 01-May-2013
• Refers: ASTM E344-12 - Terminology Relating to Thermometry and Hydrometry
• Effective Date: 01-May-2012
• Refers: ASTM E1594-11 - Standard Guide for Expression of Temperature
• Effective Date: 01-Nov-2011
• Refers: ASTM E344-10 - Terminology Relating to Thermometry and Hydrometry
• Effective Date: 01-Nov-2010
• Refers: ASTM E344-08 - Terminology Relating to Thermometry and Hydrometry
• Effective Date: 15-Nov-2008
• Refers: ASTM E344-07 - Terminology Relating to Thermometry and Hydrometry
• Effective Date: 01-Jun-2007
• Refers: ASTM E1594-06 - Standard Guide for Expression of Temperature
• Effective Date: 01-Nov-2006
• Refers: ASTM E344-06 - Terminology Relating to Thermometry and Hydrometry
• Effective Date: 01-May-2006
• Refers: ASTM D1193-06 - Standard Specification for Reagent Water
• Effective Date: 01-Mar-2006
• Refers: ASTM E344-02 - Terminology Relating to Thermometry and Hydrometry
• Effective Date: 10-Oct-2002
• Refers: ASTM E344-00 - Terminology Relating to Thermometry and Hydrometry
• Effective Date: 10-Oct-2001

Overview

ASTM E563-22: Standard Practice for Preparation and Use of an Ice-Point Bath as a Reference Temperature is an internationally recognized guideline published by ASTM International. This standard defines procedures for preparing, maintaining, and using an ice-point bath - a mixture of shaved ice and water saturated with air at one atmosphere pressure - as a reference temperature, typically 0°C. Widely used in laboratory and industrial temperature calibration, the ice-point bath offers a practical, easily reproducible fixed-point temperature reference for various thermometry applications. The standard covers best practices to ensure bath integrity and precise realization of the ice point, vital for accurate temperature measurement and instrument recalibration.

Key Topics

• Preparation of the Ice-Point Bath:

  • Use of high-purity, distilled, or reagent-grade water (Type IV or better)
  • Formation of the bath with finely shaved or crushed ice saturated with chilled water
  • Ensuring the bath is open to the atmosphere and in thermal equilibrium before use

• Bath Maintenance:

  • Regular removal of excess melt water, which can raise the bath temperature above the true ice point
  • Addition of ice and chilled water as needed to maintain slush consistency
  • Prevention of contamination, as impurities affect accuracy

• Thermometer Immersion:

  • Proper immersion depth for resistance thermometers, thermocouples, and liquid-in-glass thermometers
  • Ensuring thermal equilibrium between the device under calibration and the bath

• Sources of Error:

  • Impurities in water, excess water, insufficient ice-to-water ratios, or improper preparation
  • Effects of atmospheric and hydrostatic pressure on bath temperature
  • Thermal conduction, radiation, or Joule heating from devices

• Reference Points in Temperature Scales:

  • The ice point as a practical fixed point, especially where the higher-accuracy water triple point is unavailable or not required

Applications

ASTM E563-22 is essential across sectors that require precise temperature measurement and calibration, including:

• Calibration of Thermometers:

  • Reference bath for periodic recalibration of resistance thermometers, thermocouples, and liquid-in-glass thermometers at 0°C

• Industrial and Laboratory Quality Assurance:

  • Ensuring traceability of temperature measurements to internationally recognized reference points
  • Useful where more complex fixed-point cells (like the water triple point) are impractical or unnecessary

• Resistance Thermometry:

  • Used to set or check the zero point for Standard Platinum Resistance Thermometers (SPRTs) and industrial thermometers

• Thermoelectric Thermometry:

  • Ice-point baths serve as stable reference junctions for thermocouple measurement systems

• Glass Thermometry:

  • Supports recalibration and drift-checking of liquid-in-glass thermometers due to mechanical glass relaxation over time

Related Standards

• ASTM D1193 - Specification for Reagent Water:
  Specifies water purity required for ice-point bath preparation.

• ASTM E344 - Terminology Relating to Thermometry and Hydrometry:
  Provides essential definitions related to temperature measurement.

• ASTM E1594 - Guide for Expression of Temperature:
  Outlines protocols for expressing and interpreting temperature values.

• ITS-90 (International Temperature Scale of 1990):
  Reference for alignment of temperature scales using fixed points like the water triple point and ice point.

Practical Value

Implementing the guidelines from ASTM E563-22 ensures accurate, reproducible temperature reference points crucial for the calibration and validation of temperature sensors and instruments. Proper application of this standard minimizes uncertainties and errors, supports compliance with metrological traceability, and enhances confidence in temperature-dependent processes across scientific and industrial domains. By following this practice, organizations benefit from cost-effective, straightforward temperature calibration solutions that align with international standards.

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: E563 − 22
Standard Practice for
Preparation and Use of an Ice-Point Bath as a Reference
Temperature
This standard is issued under the fixed designation E563; 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 3. Terminology
1.1 Thispracticecoversamethodofpreparing,maintaining, 3.1 Definitions—Definitions given in Terminology E344,
and using a temperature reference bath of a mixture of shaved unless otherwise defined herein, apply to terms as used in this
ice and water, saturated with air at a pressure of 101 325 Pa (1 practice.
atm).
3.2 Temperature relationships given in Guide E1594, unless
1.2 An industrial practice for relating values referenced to otherwise defined herein, apply to temperature values as used
the ice point and to the water triple point on the ITS-90 is in this practice.
included.
3.3 Definitions of Terms Specific to This Standard:
1.3 Methods to promote uniformity of bath temperature by 3.3.1 ice-point bath, n—physical system containing ice and
mechanical stirring or agitation are not described in detail. water assembled to realize the ice point as a reference
temperature, or to establish a constant temperature near 0 °C.
1.4 Methods of approximating the ice point, as by
thermostatically-controlled refrigeration, are not covered by
4. Summary of Practice
this practice.
4.1 The ice-point bath described by this practice consists of
1.5 This standard does not purport to address all of the
an intimate mixture, without voids, of pure shaved ice or ice
safety concerns, if any, associated with its use. It is the
particles and distilled air-saturated water in a thermally insu-
responsibility of the user of this standard to establish appro-
lating vessel open to the atmosphere.
priate safety, health, and environmental practices and deter-
4.2 The ice bath realization of the ice point physically
mine the applicability of regulatory limitations prior to use.
approximates, with small uncertainty, a natural fixed-point
1.6 This international standard was developed in accor-
temperature.
dance with internationally recognized principles on standard-
4.2.1 An ice-point bath prepared by rigorous application of
ization established in the Decision on Principles for the
this practice, using distilled-water ice and air-saturated, chilled
Development of International Standards, Guides and Recom-
distilled water, typically has a temperature of 0.000 °C 6
mendations issued by the World Trade Organization Technical
0.002 °C at a barometric pressure of 101 325 Pa (1 standard
Barriers to Trade (TBT) Committee.
atmosphere). See Section 8, Precision and Bias.
4.2.2 The ice-point bath is open to the atmosphere. Equili-
2. Referenced Documents
bration of the liquid phase of the ice bath with the air is
2.1 ASTM Standards:
necessary for a stable equilibrium temperature. Changes in the
D1193 Specification for Reagent Water
localatmosphericpressurewillresultincorrespondingchanges
E344 Terminology Relating to Thermometry and Hydrom-
in the ice bath temperature (see 8.5.4, Precision and Bias).
etry
4.3 The ice-bath temperature can also be measured with an
E1594 Guide for Expression of Temperature
accurately calibrated thermometer or compared to a water
triple point cell and the bath temperature reported as the
ThispracticeisunderthejurisdictionofASTMCommitteeE20onTemperature measured temperature with an uncertainty that is attributed to
Measurement and is the direct responsibility of Subcommittee E20.07 on Funda-
the measurement, not to the ice point.
mentals in Thermometry.
Current edition approved May 1, 2022. Published August 2022. Originally
5. Significance and Use
approved in 1976. Last previous edition approved in 2016 as E563 – 11 (2016).
DOI: 10.1520/E0563-22.
5.1 This practice is adequate for use with other ASTM
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
standards that specify the ice point as a reference. It is also
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
intended to be adequate for most other ice-point reference
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. purposes.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E563 − 22
5.2 The ice point is a common practical industrial reference delayed long enough to establish thermal equilibrium, and the
point of thermometry. The ice point is relatively simple to particles shall be sufficiently small so that the bath approaches
realize and provides a readily available natural fixed-point the required state of ice and air-saturated water in intimate
reference temperature. contact.
5.3 Use in Resistance Thermometry:
6.4 Cleanliness is essential as small amounts of dissolved
5.3.1 The ice point was a defining fixed point on practical salts, and other contaminants can cause the equilibrium tem-
temperature scales prior to 1960.
perature to be below that of the ice-point temperature.
5.3.2 The ITS-90 definesW(T ) = R(T )/R(273.16 K), the
90 90
measured resistance ratio of a Standard Platinum Resistance
7. Procedure
Thermometer (SPRT), in reference to the water triple point, not
7.1 In the practical use of the ice-point bath, two objectives
the ice point (1). In many instances, where the water triple
shall be accomplished: (1) the bath shall be established and
point is not available, or when the accuracy obtainable with the
maintained so that its temperature is a good approximation to
water triple point is not required, reference to a properly
that of the ice point, and (2) the object for which the reference
established and maintained ice-point reference is used. For
temperature is to be obtained shall be in thermal equilibrium
industrial-quality resistance thermometers, the resistance value
with the water-ice equilibrium temperature (water-ice interface
is determined for 0 °C, and an uncertainty that is appropriate
temperature).
for the quality of the ice-point realization is assigned.
7.2 Establishing the Ice-Point:
5.4 Use in Thermoelectric Thermometry:
7.2.1 All equipment that comes in contact with the water
5.4.1 In thermoelectric thermometry, the ice point is ordi-
andiceofanice-pointbathshallbeclean.Thoroughlyrinsethe
narily used as the reference temperature (2).
equipment with tap water, then rinse with the type of water
5.4.2 Adequate thermoelectric reference requires that ther-
used for the ice-point bath medium. Use clean plastic gloves to
mocouple junctions be well-coupled thermally to the bath,
handle the ice and equipment.
electrically isolated from each other and from the bath, and
7.2.2 UsewaterofpurityequivalenttoorbetterthantypeIV
adequately immersed to avoid perturbing the reference-
reagent water, Specification D1193, for the ice-point bath
junction temperatures by radiation and longitudinal conduction
medium. Chill a quantity of the water to near 0 °C in a flask
of heat along the thermoelements (3 and 4).
and shake vigorously to aerate the water. Freeze another
5.5 Use in Liquid-in-Glass Thermometry:
portion of the water to produce ice for the bath.
5.5.1 In liquid-in-glass thermometry, the ice point is ordi-
7.2.3 Prepare finely divided ice by shaving or crushing.
narily used as the reference temperature (5).
Shaved ice resembling snow is preferred, but crushed ice is
5.5.2 The periodic recalibration of a liquid-in-glass ther-
acceptable if the particles are small (not exceeding 2 mm to
mometer at the ice point provides a reliable indication of the
3 mm in diameter).
effectofgradualrelaxationofresidualmechanicalstrainsinthe
7.2.4 Prepare the bath in a clean thermally insulated vessel,
glass that have a significant effect on the volume of the bulb
preferably a wide-mouthed Dewar vacuum flask fitted with an
(5).
insulating closure such as a stopper. The vessel should be large
enough that its size does not affect the water-ice equilibrium
6. Hazards
temperature and of such diameter and depth that in thermal
6.1 Excess water accumulating in any region, particularly equilibrium the test objects will not significantly modify the
around the reference location, can elevate the temperature in temperature of the bath over the region to which the ice point
that vicinity above the ice point. Errors, usually somewhat less is to be applied. For usual applications, a diameter of at least
than4 °C,canoccurfromthiscauseinpoorlymaintainedbaths 70 mm and a depth of at least 300 mm may be adequate.
and with poorly positioned test objects (3 and 4).
7.2.5 Alternately add shaved ice and chilled water to the
vessel, using enough water to saturate the ice but not enough to
6.2 For a stirred bath, the temperature of the bath will
float it. As the vessel fills, compress the ice-water mixture to
depend on the heat gained by the bath, the amount of water and
force out excess water. The objective is to surround each
ice, and the vigor of stirring. The uniformity of temperature of
particle of ice with water, filling all voids, but to keep the ice
the bath can be enhanced by slowly stirring or agitating the
particles as close together as possible. Continue adding ice and
slush of ice and water either manually or by a powered stirring
water and compressing until the vessel is filled to the requi
...

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: E563 − 11 (Reapproved 2016) E563 − 22
Standard Practice for
Preparation and Use of an Ice-Point Bath as a Reference
Temperature
This standard is issued under the fixed designation E563; 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 practice covers a method of preparing, maintaining, and using a temperature reference bath of a mixture of shaved ice
and water, saturated with air at a pressure of 101 325 Pa 101 325 Pa (1 atm).
1.2 An industrial practice for relating values referenced to the ice point and to the water triple point on the ITS-90 is included.
1.3 Methods to promote uniformity of bath temperature by mechanical stirring or agitation are not described in detail.
1.4 Methods of approximating the ice point, as by thermostatically-controlled refrigeration, are not covered by this practice.
1.5 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.
1.6 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
2.1 ASTM Standards:
D1193 Specification for Reagent Water
E344 Terminology Relating to Thermometry and Hydrometry
E1594 Guide for Expression of Temperature
3. Terminology
3.1 Definitions—Definitions given in Terminology E344, unless otherwise defined herein, apply to terms as used in this practice.
3.2 Temperature relationships given in Guide E1594, unless otherwise defined herein, apply to temperature values as used in this
practice.
This practice 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, 2016May 1, 2022. Published May 2016August 2022. Originally approved in 1976. Discontinued February 1996 and reinstated in 1997
as E563 – 97.Last previous ediitonedition approved in 20112016 as E563 – 11.E563 – 11 (2016). DOI: 10.1520/E0563-11R16.10.1520/E0563-22.
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.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E563 − 22
3.3 Definitions of Terms Specific to This Standard:
3.3.1 ice-point bath, n—physical system containing ice and water assembled to realize the ice point as a reference temperature,
or to establish a constant temperature near 0 °C.
4. Summary of Practice
4.1 The ice-point bath described by this practice consists of an intimate mixture, without voids, of pure shaved ice or ice particles
and distilled air-saturated water in a thermally insulating vessel open to the atmosphere.
4.2 The ice bath realization of the ice point physically approximates, with small uncertainty, a natural fixed-point temperature.
4.2.1 An ice-point bath prepared by rigorous application of this practice, using distilled-water ice and air-saturated, chilled
distilled water, typically has a temperature of 0.0000.000 °C 6 0.002 °C at a barometric pressure of 101,325101 325 Pa (1 standard
atmosphere). See Section 8, Precision and Bias.
4.2.2 The ice-point bath is open to the atmosphere. The solubility of air in water, which affects phase change, is directly
proportional to the atmospheric pressure. The effect of barometric pressure on the pure ice point is −74 nK/Pa (−7.5 mK/atm). With
saturated air in solution, the effect is increased to approximately -0.1 μK/Pa (-10 mK/atm). The initial pressure gradient with
elevation in the atmosphere is approximately -11.4 Pa/m. Accordingly, the change in the air-saturated ice-point temperature
resulting from an increase in elevation above sea level is approximately 1.1 mK/km for the first 1000 m increaseEquilibration of
the liquid phase of the ice bath with the air is necessary for a stable equilibrium temperature. Changes in the local atmospheric
pressure will result in corresponding changes in the ice bath temperature (see 8.5.4in altitude (0.33 mK per 1000 ft increase in
altitude)., Precision and Bias).
4.3 The ice-bath temperature can also be measured with an accurately calibrated thermometer or compared to a water triple point
cell and the bath temperature reported as the measured temperature with an uncertainty that is attributed to the measurement, not
to the ice point.
5. Significance and Use
5.1 This practice is adequate for use with other ASTM standards that specify the ice point as a reference. It is also intended to
be adequate for most other ice-point reference purposes.
5.2 The ice point is a common practical industrial reference point of thermometry. The ice point is relatively simple to realize and
provides a readily available natural fixed-point reference temperature.
5.3 Use in Resistance Thermometry : Thermometry:
5.3.1 The ice point was a defining fixed point on practical temperature scales prior to 1960.
5.3.2 The ITS-90 defines W(T ) = R(T )/R(273.16 K), the measured resistance ratio of a Standard Platinum Resistance
90 90
Thermometer (SPRT), in reference to the water triple point, not the ice point (1). In many instances, where the water triple point
is not available, or when the accuracy obtainable with the water triple point is not required, reference to a properly established and
maintained ice-point reference is used. For industrial-quality resistance thermometers, the resistance value is determined for 0 °C,
and an uncertainty that is appropriate for the quality of the ice-point realization is assigned.
5.4 Use in Thermoelectric Thermometry:
5.4.1 In thermoelectric thermometry, the ice point is ordinarily used as the reference temperature (2).
5.4.2 Adequate thermoelectric reference requires that thermocouple junctions be well-coupled thermally to the bath, electrically
isolated from each other and from the bath, and adequately immersed to avoid perturbing the reference-junction temperatures by
radiation and longitudinal conduction of heat along the thermoelements (3 and 4).
The boldface numbers in parentheses refer to the list of references at the end of this standard.
E563 − 22
5.5 Use in Liquid-in-Glass Thermometry:
5.5.1 In liquid-in-glass thermometry, the ice point is ordinarily used as the reference temperature (5).
5.5.2 The periodic recalibration of a liquid-in-glass thermometer at the ice point provides a reliable indication of the effect of
gradual relaxation of residual mechanical strains in the glass that have a significant effect on the volume of the bulb (5).
6. Hazards
6.1 Excess water accumulating in any region, particularly around the reference location, can elevate the temperature in that
vicinity above the ice point. Errors, usually somewhat less than 4 °C, can occur from this cause in poorly maintained baths and
with poorly positioned test objects (3 and 4).
6.2 For a stirred bath, the temperature of the bath will depend on the heat gained by the bath, the amount of water and ice, and
the vigor of stirring. The uniformity of temperature of the bath can be enhanced by slowly stirring or agitating the slush of ice and
water either manually or by a powered stirring means so that all of the ice and water in the bath come into intimate contact.
6.3 Ice making machines operate below 0 °C. Therefore, when excessively large ice particles are used to prepare the ice-point
bath, the initial temperature of the bath can briefly be slightly below the ice point. Also, some of the water may freeze and bridge
some of the particles. Use of the bath must be delayed long enough to establish thermal equilibrium, and the particles shall be
sufficiently small so that the bath approaches the required state of ice and air-saturated water in intimate contact.
6.4 Cleanliness is essential as small amounts of dissolved salts, and other contaminants can cause the equilibrium temperature to
be below that of the ice-point temperature.
7. Procedure
7.1 In the practical use of the ice-point bath, two objectives shall be accomplished: (1) the bath shall be established and maintained
so that its temperature is a good approximation to that of the ice point, and (2) the object for which the reference temperature is
to be obtained shall be in thermal equilibrium with the water-ice equilibrium temperature (water-ice interface temperature).
7.2 Establishing the Ice-Point : Ice-Point:
7.2.1 All equipment that comes in contact with the water and ice of an ice-point bath shall be clean. Thoroughly rinse the
equipment with tap water, then rinse with the type of water used for the ice-point bath medium. Use clean plastic gloves to handle
the ice and equipment.
7.2.2 Use water of purity equivalent to or better than type IV reagent water, Specification D1193, for the ice-point bath medium.
Chill a quantity of the water to near 0 °C in a flask and shake vigorously to aerate the water. Freeze another portion of the water
to produce ice for the bath.
7.2.3 Prepare finely divided ice by shaving or crushing. Shaved ice resembling snow is preferred, but crushed ice is acceptable
if the particles are small (not exceeding 22 mm to 3 mm 3 mm in diameter).
7.2.4 Prepare the bath in a clean thermally insulated vessel, preferably a wide-mouthed Dewar vacuum flask fitted with an
insulating
...