ASTM C1114-00(2006)
(Test Method)Standard Test Method for Steady-State Thermal Transmission Properties by Means of the Thin-Heater Apparatus
Standard Test Method for Steady-State Thermal Transmission Properties by Means of the Thin-Heater Apparatus
SCOPE
1.1 This test method covers the determination of the steady-state thermal transmission properties of flat-slab specimens of thermal insulation using a thin heater of uniform power density having low lateral heat flow. A thin heater with low lateral thermal conductance can reduce unwanted lateral heat flow and avoid the need for active-edge guarding.
1.2 This primary test method of thermal-transmission measurement describes a principle, rather than a particular apparatus. The principle involves determination of the thermal flux across a specimen of known thickness and the temperatures of the hot and cold faces of the specimen.
1.3 Considerable latitude is given to the designer of the apparatus in this test method; since a variety of designs is possible, a procedure for qualifying an apparatus is given in .
1.4 The specimens must meet the following conditions if thermal resistance or thermal conductance of the specimen is to be determined by this test method:
1.4.1 The portion of the specimen over the isothermal area of the heater must accurately represent the whole specimen.
1.4.2 The remainder of the specimen should not distort the heat flow in that part of the specimen defined in .
1.4.3 The specimen shall be thermally homogeneous such that the thermal conductivity is not a function of the position within the sample, but rather may be a function of direction, time, and temperature. The specimen shall be free of holes, of high-density volumes, and of thermal bridges between the test surfaces or the specimen edges.
1.4.4 Test Method C 177 describes tests that can help ascertain whether conditions of are satisfied. For the purposes of this test method, differences in the measurements of less than 2 % may be considered insignificant, and the requirements fulfilled.
1.5 The specimens shall meet one of the following requirements, in addition to those of .
1.5.1 If homogeneous materials as defined in Terminology C 168 are tested, then the thermal resistivity and thermal conductivity can be determined by this test method.
1.5.2 If materials which are layered or otherwise thermally inhomogeneous are tested, thermal resistance and thermal conductance can be determined by this test method.
1.6 Two versions of thin-heater apparatus using the same principle of the standard are described in and . They are similar in concept but differ in size and construction, and hence warrant separate descriptions for each design. This test method in no way limits the size of the thin-heater element. One of the units described uses a thin metal foil, while the other uses a metal screen as the heat source. The smaller, foil apparatus is designed to make rapid measurements of heat transmission through specimens as thin as 0.5 cm and as thick as 2 cm; however, an apparatus using a foil heater could be designed to measure much thicker materials, if desired. The larger, screen apparatus is designed to measure specimens with thicknesses between 3 and 15 cm, where the exact limits depend on the thermal resistance of the specimens. Both apparatuses use thermocouples for measuring temperature, but other temperature-sensing systems can be used.
1.7 This test method covers the theory and principles of the measurement technique. It does not provide details of construction other than those required to illustrate two devices which meet the prescribed requirements. Detailed information is available in References () and the Adjunct.
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 health practices and determine the applicability of regulatory limitations prior to use.
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Designation: C 1114 – 00 (Reapproved 2006)
Standard Test Method for
Steady-State Thermal Transmission Properties by Means of
the Thin-Heater Apparatus
This standard is issued under the fixed designation C1114; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope of less than 2% may be considered insignificant, and the
requirements fulfilled.
1.1 Thistestmethodcoversthedeterminationofthesteady-
1.5 The specimens shall meet one of the following require-
state thermal transmission properties of flat-slab specimens of
ments, in addition to those of 1.4.
thermalinsulationusingathinheaterofuniformpowerdensity
1.5.1 If homogeneous materials as defined in Terminology
having low lateral heat flow. A thin heater with low lateral
C168 are tested, then the thermal resistivity and thermal
thermalconductancecanreduceunwantedlateralheatflowand
conductivity can be determined by this test method.
avoid the need for active-edge guarding.
1.5.2 If materials which are layered or otherwise thermally
1.2 This primary test method of thermal-transmission mea-
inhomogeneous are tested, thermal resistance and thermal
surement describes a principle, rather than a particular appa-
conductance can be determined by this test method.
ratus. The principle involves determination of the thermal flux
1.6 Two versions of thin-heater apparatus using the same
across a specimen of known thickness and the temperatures of
principleofthestandardaredescribedinAnnexA1andAnnex
the hot and cold faces of the specimen.
A2. They are similar in concept but differ in size and
1.3 Considerable latitude is given to the designer of the
construction, and hence warrant separate descriptions for each
apparatus in this test method; since a variety of designs is
design. This test method in no way limits the size of the
possible, a procedure for qualifying an apparatus is given in
thin-heater element. One of the units described uses a thin
5.3.
metal foil, while the other uses a metal screen as the heat
1.4 The specimens must meet the following conditions if
source. The smaller, foil apparatus is designed to make rapid
thermalresistanceorthermalconductanceofthespecimenisto
measurements of heat transmission through specimens as thin
be determined by this test method :
as 0.5 cm and as thick as 2 cm; however, an apparatus using a
1.4.1 The portion of the specimen over the isothermal area
foil heater could be designed to measure much thicker mate-
of the heater must accurately represent the whole specimen.
rials, if desired. The larger, screen apparatus is designed to
1.4.2 The remainder of the specimen should not distort the
measure specimens with thicknesses between 3 and 15 cm,
heat flow in that part of the specimen defined in 1.4.1.
where the exact limits depend on the thermal resistance of the
1.4.3 The specimen shall be thermally homogeneous such
specimens. Both apparatuses use thermocouples for measuring
that the thermal conductivity is not a function of the position
temperature, but other temperature-sensing systems can be
within the sample, but rather may be a function of direction,
used.
time, and temperature. The specimen shall be free of holes, of
1.7 This test method covers the theory and principles of the
high-density volumes, and of thermal bridges between the test
measurementtechnique.Itdoesnotprovidedetailsofconstruc-
surfaces or the specimen edges.
tion other than those required to illustrate two devices which
1.4.4 Test Method C177 describes tests that can help
meet the prescribed requirements. Detailed information is
ascertain whether conditions of 1.4 are satisfied. For the
available in References (1-23) and the Adjunct.
purposes of this test method, differences in the measurements
1.8 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
ThistestmethodisunderthejurisdictionofASTMCommitteeC16onThermal responsibility of the user of this standard to establish appro-
Insulation and is the direct responsibility of Subcommittee C16.30 on Thermal
priate safety and health practices and determine the applica-
Measurement.
bility of regulatory limitations prior to use.
Current edition approved March 1, 2006. Published March 2006. Originally
approved 1989. Last previous edition approved 2000 as C1114–00.
Further discussion on the definition of these limitations may be found in Tye,
R. P., “What Property Do We Measure?,” Heat Transmission Measurements in Theboldfacenumbersinparenthesesrefertothelistofreferencesattheendof
Thermal Insulations, ASTM STP 544, ASTM, 1974, pp 5–12. this test method.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
C 1114 – 00 (2006)
2. Referenced Documents screen heater is very thin, the need for a gap between the inner
and outer heater regions to act respectively as hot-plate and
2.1 ASTM Standards:
guard, is unnecessary.
C168 Terminology Relating to Thermal Insulation
C177 Test Method for Steady-State Heat Flux Measure-
5. Significance and Use
ments and Thermal Transmission Properties by Means of
the Guarded-Hot-Plate Apparatus
5.1 Factors that may influence the thermal-transmission
C518 Test Method for Steady-State Thermal Transmission
properties of a specimen of material are described in Practice
Properties by Means of the Heat Flow Meter Apparatus
C1045 and the Precision and Bias section of Test Method
C687 Practice for Determination of Thermal Resistance of
C177.
Loose-Fill Building Insulation
5.2 Because of the required test conditions prescribed by
C1043 Practice for Guarded-Hot-Plate Design Using Cir-
this test method, it shall be recognized that the thermal
cular Line-Heat Sources
properties obtained will not necessarily apply without modifi-
C1044 Practice for Using a Guarded-Hot-Plate Apparatus
cation to all conditions of service. As an example, this test
or Thin-Heater Apparatus in the Single-Sided Mode
method normally provides that the thermal properties shall be
C1045 Practice for Calculating Thermal Transmission
obtained on specimens that do not contain moisture, although
Properties Under Steady-State Conditions
in service such conditions may not be realized. Even more
C1058 Practice for Selecting Temperatures for Evaluating
basic is the dependence of the thermal properties on variables
and Reporting Thermal Properties of Thermal Insulation
such as mean temperature and temperature difference.
E177 Practice for Use of the Terms Precision and Bias in
5.3 Whenanewormodifieddesignofapparatusisevolved,
ASTM Test Methods
tests shall be made on at least two sets of differing material of
2.2 ASTM Adjuncts:
knownlong-termthermalstability.Testsshallbemadeforeach
Descriptions of Two Types of Thin-Heater Apparatus
material at a minimum of two different mean temperatures
within the operating range of each. Any differences in results
3. Terminology
should be carefully studied to determine the cause and then be
3.1 Applicable terms and symbols are defined in Terminol-
removed by appropriate action. Only after a successful verifi-
ogy C168. Any terms or symbols not included in C168 but
cation study on materials having known thermal properties
used in this test method will be defined within the text.
traceable to a recognized national standards laboratory shall
test results obtained with this apparatus be considered to
4. Summary of Test Method
conform with this test method. Periodic checks of apparatus
4.1 Principles:
performance are recommended.
4.1.1 Athin-foil or metal-screen heating apparatus operates
5.4 The thermal transmission properties of many materials
in accordance with the basic concept of a unidimensional,
depend upon the prior thermal history. Care must be exercised
longitudinal heat-flow technique. The heater is made suffi-
when testing such specimens at a number of conditions so that
ciently thin so that lateral heat flow along the plane of the
testsareperformedinasequencethatlimitssucheffectsonthe
heater is insignificant, and so that there is no need for isolation
results.
and separate temperature control of a guard region, except
5.5 Typical uses for the thin-heater apparatus include the
possibly the control of ambient temperature.
following:
4.1.2 The low mass of the thin heater apparatus minimizes
5.5.1 Product development and quality control applications.
drift error and allows the apparatus to reach steady-state in a
5.5.2 Measurement of thermal conductivity at desired mean
significantly shorter time than a typical Test Method C177
temperatures.
apparatus.
5.5.3 Thermal properties of specimens that are moist or
4.1.3 It should be noted that all quantities in this procedure
close to melting point or other critical temperature (see Note
are determined by direct measurement. There are no arbitrary
1).
factors requiring calibration by comparison with a standard:
thus, the apparatus yields results on an absolute basis.
NOTE 1—Apparatusofthetypecoveredbythistestmethodapplytothe
study of thermal properties of specimens containing moisture because of
4.1.4 Aproperly designed heater will be sufficiently thin to
the use of small temperature differences and the low thermal capacity of
reduce lateral heat flow from the central zone to an acceptably
the heat source.
small level. The result is that within a central zone, one-
dimensional, longitudinal flow of heat perpendicular to the
5.5.4 Determination of thermal properties of relatively high
heater is obtained through the specimen. Because the foil or
R value insulation samples with large apparatuses. In the case
of the metal-screen heater apparatus, samples with thicknesses
up to 15 cm can be measured.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
6. Apparatus and Specimen Preparation
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website.
6.1 The simplicity of this test procedure may cause very
Consult Test Methods C177, C518, and Practice C1045 for the correct
important factors to be overlooked which may affect the
application of this test method.
results. To ensure accuracy of measurements, the user of this
Available from ASTM International Headquarters. Order Adjunct No.
ADJC1114. apparatusshouldknowhowtomeasuretemperatureandpower
C 1114 – 00 (2006)
as they relate to testing of thermal resistance. It is also heater area. For more specific quantitative information on this
necessarythatthespecimensbeproperlyselectedandprepared limitation see Refs. (24), (25), (26), and (27).
for evaluation.
7.2.1.1 The specimen may be sized to extend beyond the
6.2 Normally, test specimens are selected in pairs from the
meteredareabyadistancesufficienttoensureone-dimensional
sample lot. The specimens selected should be uniform and
heat flow within the metered area.
homogeneous to ensure that test apparatus symmetry is main-
7.2.2 Homogeneity— There are two potential problems in
tained. Appropriate thermal modeling may allow tests of
determining the heat flux through highly inhomogeneous
nonuniform specimens, such as small specimens positioned
specimens. One is related to the interpretation and application
within larger ones, or composite or layered specimens.
of the resulting data; it is discussed in Practice C1045. The
6.3 Test specimens shall be prepared and conditioned in
other is connected with the degradation in performance of the
accordance with the appropriate material specification. The
apparatus. If the specimen itself is highly inhomogeneous, that
conditioning of the test specimens shall be reported.
is, the heat flux density varies appreciably over the metered
6.3.1 The surfaces of the specimens shall be prepared to
area, several errors can be significantly increased. The tem-
ensure uniform thermal contact with the heater and
perature distribution of the thin heater can deviate appreciably
temperature-controlled plates. Further details may be found in
from isothermal conditions which, in turn, can cause large
the Specimen Preparation section of Test Method C177.
uncertainties in the average temperature difference across the
6.3.2 When evaluating compressible specimens, provide
specimen. The increased temperature variations of the thin
means to maintain a definite, known test thickness. One
heater can also lead to increased edge heat losses. The
method is to insert rigid equal-length spacers made of low
importance of measuring temperatures of the thin heater or
thermal-conductivity material in the corners of specimens.An
specimensurfaceatnumerouspointsisgreatlyincreasedunder
alternative method involves using mechanical arrangements to
such conditions.
establishfixedandknownspacingandparallelismbetweenthe
7.3 Specimen Preparation and Installation—The specimen
heater and cold plates.
shall be conditioned in accordance with the appropriate mate-
6.3.3 The maximum allowable distance between the heater
rial specification. The following guidelines for specimen
andcoldplates(specimenthickness)islimitedbythespecimen
preparationapplywhenthematerialspecificationisincomplete
thermal resistance, the ambient temperature, and the ratio of
or unavailable. In general, the surfaces of the specimen should
measurement area to apparatus size. The isothermal area
be prepared to ensure uniform thermal contact with the thin
established in the center of the heater is influenced by these
heater and the cooling plates.
factors. The isothermal area must be large enough to establish
7.3.1 Compressible Specimens—Also, for compressible
the equilibrium heat flux (W/m ) through a representative area
specimensthesurfacesoftheuncompressedspecimensmaybe
of the specimen. References are presented which will help
comparatively rough so long as these undulations essentially
guide users in determining the maximum thickness that can be
vanish under test compression. Under more extreme condi-
used for specimens in their apparatus.
tions, it may be necessary to smooth the specimen surfaces to
6.4 Thedistancebetweentheheaterandthecoldplatesmust
achieve better specimen contact. If the apparent thermal
beadjustedtoconfinethespecimenswithpressuresufficientto
conductivity of the contact void is greater than that of the
ensure good thermal contact between the specimens and the
specimen, the measured R value will be smaller than the R
bounding surfaces. For rigid specimens, a pressure of 2.5 kPa
valuethatwouldbeobtainedifthevoidswereabsent.Thisma
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