ASTM C177-19

Standard Test Method for Steady-State Heat Flux Measurements and Thermal Transmission Properties by Means of the Guarded-Hot-Plate Apparatus

SIGNIFICANCE AND USE
5.1 This test method covers the measurement of heat flux and associated test conditions for flat specimens. The guarded-hot-plate apparatus is generally used to measure steady-state heat flux through materials having a “low” thermal conductivity and commonly denoted as “thermal insulators.” Acceptable measurement accuracy requires a specimen geometry with a large ratio of area to thickness.  
5.2 Two specimens are selected with their thickness, areas, and densities as identical as possible, and one specimen is placed on each side of the guarded-hot-plate. The faces of the specimens opposite the guarded-hot-plate and primary guard are placed in contact with the surfaces of the cold surface assemblies.  
5.3 Steady-state heat transmission through thermal insulators is not easily measured, even at room temperature. This is due to the fact heat transmission through a specimen occurs by any or all of three separate modes of heat transfer (radiation, conduction, and convection). It is possible that any inhomogeneity or anisotropy in the specimen will require special experimental precautions to measure that flow of heat. In some cases it is possible that hours or even days will be required to achieve the thermal steady-state. No guarding system can be constructed to force the metered heat to pass only through the test area of insulation specimen being measured. It is possible that moisture content within the material will cause transient behavior. It is also possible that and physical or chemical change in the material with time or environmental condition will permanently alter the specimen.  
5.4 Application of this test method on different test insulations requires that the designer make choices in the design selection of materials of construction and measurement and control systems. Thus it is possible that there will be different designs for the guarded-hot-plate apparatus when used at ambient versus cryogenic or high temperatures. Test thickness, temperature range,...
SCOPE
1.1 This test method establishes the criteria for the laboratory measurement of the steady-state heat flux through flat, homogeneous specimen(s) when their surfaces are in contact with solid, parallel boundaries held at constant temperatures using the guarded-hot-plate apparatus.  
1.2 The test apparatus designed for this purpose is known as a guarded-hot-plate apparatus and is a primary (or absolute) method. This test method is comparable, but not identical, to ISO 8302.  
1.3 This test method sets forth the general design requirements necessary to construct and operate a satisfactory guarded-hot-plate apparatus. It covers a wide variety of apparatus constructions, test conditions, and operating conditions. Detailed designs conforming to this test method are not given but must be developed within the constraints of the general requirements. Examples of analysis tools, concepts and procedures used in the design, construction, calibration and operation of a guarded-hot-plate apparatus are given in Refs (1-41).2  
1.4 This test method encompasses both the single-sided and the double-sided modes of measurement. Both distributed and line source guarded heating plate designs are permitted. The user should consult the standard practices on the single-sided mode of operation, Practice C1044, and on the line source apparatus, Practice C1043, for further details on these heater designs.  
1.5 The guarded-hot-plate apparatus can be operated with either vertical or horizontal heat flow. The user is cautioned however, since the test results from the two orientations may be different if convective heat flow occurs within the specimens.  
1.6 Although no definitive upper limit can be given for the magnitude of specimen conductance that is measurable on a guarded-hot-plate, for practical reasons the specimen conductance should be less than 16 W/(m2K).  
1.7 This test method is applicable to the measurement of a wide variety of sp...

General Information

• Status: Historical
• Publication Date: 31-Dec-2018
• ICS: 17.200.10 - Heat. Calorimetry
• Technical Committee: C16 - Thermal Insulation
• Drafting Committee: C16.30 - Thermal Measurement

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: C177 − 19
Standard Test Method for
Steady-State Heat Flux Measurements and Thermal
Transmission Properties by Means of the Guarded-Hot-Plate
1
Apparatus
This standard is issued under the fixed designation C177; 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.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope 1.6 Although no definitive upper limit can be given for the
magnitude of specimen conductance that is measurable on a
1.1 This test method establishes the criteria for the labora-
guarded-hot-plate, for practical reasons the specimen conduc-
tory measurement of the steady-state heat flux through flat,
2
tance should be less than 16 W/(m K).
homogeneous specimen(s) when their surfaces are in contact
with solid, parallel boundaries held at constant temperatures
1.7 This test method is applicable to the measurement of a
using the guarded-hot-plate apparatus.
wide variety of specimens, ranging from opaque solids to
porous or transparent materials, and a wide range of environ-
1.2 The test apparatus designed for this purpose is known as
mental conditions including measurements conducted at ex-
a guarded-hot-plate apparatus and is a primary (or absolute)
tremes of temperature and with various gases and pressures.
method. This test method is comparable, but not identical, to
ISO 8302.
1.8 Inhomogeneities normal to the heat flux direction, such
as layered structures, can be successfully evaluated using this
1.3 This test method sets forth the general design require-
test method. However, testing specimens with inhomogeneities
ments necessary to construct and operate a satisfactory
in the heat flux direction, such as an insulation system with
guarded-hot-plate apparatus. It covers a wide variety of appa-
thermal bridges, can yield results that are location specific and
ratus constructions, test conditions, and operating conditions.
shall not be attempted with this type of apparatus. See Test
Detailed designs conforming to this test method are not given
Method C1363 for guidance in testing these systems.
but must be developed within the constraints of the general
requirements. Examples of analysis tools, concepts and proce-
1.9 Calculations of thermal transmission properties based
dures used in the design, construction, calibration and opera-
upon measurements using this method shall be performed in
2
tion of a guarded-hot-plate apparatus are given in Refs (1-41).
conformance with Practice C1045.
1.4 This test method encompasses both the single-sided and
1.10 In order to ensure the level of precision and accuracy
the double-sided modes of measurement. Both distributed and
expected, persons applying this standard must possess a
line source guarded heating plate designs are permitted. The
knowledge of the requirements of thermal measurements and
user should consult the standard practices on the single-sided
testing practice and of the practical application of heat transfer
mode of operation, Practice C1044, and on the line source
theory relating to thermal insulation materials and systems.
apparatus, Practice C1043, for further details on these heater
Detailed operating procedures, including design schematics
designs.
and electrical drawings, should be available for each apparatus
1.5 The guarded-hot-plate apparatus can be operated with to ensure that tests are in accordance with this test method. In
either vertical or horizontal heat flow. The user is cautioned
addition, automated data collecting and handling systems
however, since the test results from the two orientations may be connected to the apparatus must be verified as to their
different if convective heat flow occurs within the specimens.
accuracy. This can be done by calibration and inputting data
sets, which have known results associated with them, into
computer programs.
1
This test method is under the jurisdiction of ASTM Committee C16 on Thermal
1.11 It is not practical for a test method of this type to
Insulation and is the direct responsibility of Subcommittee C16.30 on Thermal
establish details of design and construction and the procedures
Measurement.
Current edition approved Jan. 1, 2019. Published January 2019. Originally
to cover all contingencies that might offer difficulties to a
approved in 1942. Last previous edition approved in 2013 as C177 – 13. DOI:
person without technical knowledge concerning theory of heat
10.1520/C0177-19.
2 flow, temperature measurements and general testing practices.
The boldface numbers given in parentheses refer to the list of references at the
...

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: C177 − 13 C177 − 19
Standard Test Method for
Steady-State Heat Flux Measurements and Thermal
Transmission Properties by Means of the Guarded-Hot-Plate
1
Apparatus
This standard is issued under the fixed designation C177; 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.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope
1.1 This test method establishes the criteria for the laboratory measurement of the steady-state heat flux through flat,
homogeneous specimen(s) when their surfaces are in contact with solid, parallel boundaries held at constant temperatures using
the guarded-hot-plate apparatus.
1.2 The test apparatus designed for this purpose is known as a guarded-hot-plate apparatus and is a primary (or absolute)
method. This test method is comparable, but not identical, to ISO 8302.
1.3 This test method sets forth the general design requirements necessary to construct and operate a satisfactory guarded-hot-
plate apparatus. It covers a wide variety of apparatus constructions, test conditions, and operating conditions. Detailed designs
conforming to this test method are not given but must be developed within the constraints of the general requirements. Examples
of analysis tools, concepts and procedures used in the design, construction, calibration and operation of a guarded-hot-plate
2
apparatus are given in Refs (1-41).
1.4 This test method encompasses both the single-sided and the double-sided modes of measurement. Both distributed and line
source guarded heating plate designs are permitted. The user should consult the standard practices on the single-sided mode of
operation, Practice C1044, and on the line source apparatus, Practice C1043, for further details on these heater designs.
1.5 The guarded-hot-plate apparatus can be operated with either vertical or horizontal heat flow. The user is cautioned however,
since the test results from the two orientations may be different if convective heat flow occurs within the specimens.
1.6 Although no definitive upper limit can be given for the magnitude of specimen conductance that is measurable on a
2
guarded-hot-plate, for practical reasons the specimen conductance should be less than 16 W/(m K).
1.7 This test method is applicable to the measurement of a wide variety of specimens, ranging from opaque solids to porous
or transparent materials, and a wide range of environmental conditions including measurements conducted at extremes of
temperature and with various gases and pressures.
1.8 Inhomogeneities normal to the heat flux direction, such as layered structures, can be successfully evaluated using this test
method. However, testing specimens with inhomogeneities in the heat flux direction, such as an insulation system with thermal
bridges, can yield results that are location specific and shall not be attempted with this type of apparatus. See Test Method C1363
for guidance in testing these systems.
1.9 Calculations of thermal transmission properties based upon measurements using this method shall be performed in
conformance with Practice C1045.
1.10 In order to ensure the level of precision and accuracy expected, persons applying this standard must possess a knowledge
of the requirements of thermal measurements and testing practice and of the practical application of heat transfer theory relating
to thermal insulation materials and systems. Detailed operating procedures, including design schematics and electrical drawings,
should be available for each apparatus to ensure that tests are in accordance with this test method. In addition, automated data
1
This test method is under the jurisdiction of ASTM Committee C16 on Thermal Insulation and is the direct responsibility of Subcommittee C16.30 on Thermal
Measurement.
Current edition approved Sept. 15, 2013Jan. 1, 2019. Published October 2013January 2019. Originally approved in 1942. Last previous edition approved in 20102013 as
C177 – 10C177 – 13. . DOI: 10.1520/C0177-13.10.1520/C0177-19.
2
The boldface numbers given in parentheses refer to the list of references at the end of this standard.
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