ASTM C1114-06(2013)
(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
SIGNIFICANCE AND USE
5.1 Factors that may influence the thermal-transmission properties of a specimen of material are described in Practice C1045 and the Precision and Bias section of Test Method C177.
5.2 Because of the required test conditions prescribed by this test method, it shall be recognized that the thermal properties obtained will not necessarily apply without modification to all conditions of service. As an example, this test method normally provides that the thermal properties shall be obtained on specimens that do not contain moisture, although in service such conditions may not be realized. Even more basic is the dependence of the thermal properties on variables such as mean temperature and temperature difference.
5.3 When a new or modified design of apparatus is evolved, tests shall be made on at least two sets of differing material of known long-term thermal stability. Tests shall be made for each material at a minimum of two different mean temperatures within the operating range of each. Any differences in results should be carefully studied to determine the cause and then be removed by appropriate action. Only after a successful verification study on materials having known thermal properties traceable to a recognized national standards laboratory shall test results obtained with this apparatus be considered to conform with this test method. Periodic checks of apparatus performance are recommended.
5.4 The thermal transmission properties of many materials depend upon the prior thermal history. Care must be exercised when testing such specimens at a number of conditions so that tests are performed in a sequence that limits such effects on the results.
5.5 Typical uses for the thin-heater apparatus include the following:
5.5.1 Product development and quality control applications.
5.5.2 Measurement of thermal conductivity at desired mean temperatures.
5.5.3 Thermal properties of specimens that are moist or close to melting point or other critical tempe...
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 5.3.
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 method2:
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 1.4.1.
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 C177 describes tests that can help ascertain whether conditions of 1.4 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 1.4.
1.5.1 If homogeneous materi...
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Designation: C1114 − 06 (Reapproved 2013)
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 (´) indicates an editorial change since the last revision or reapproval.
1. Scope this test method, differences in the measurements of less than
2% may be considered insignificant, and the requirements
1.1 Thistestmethodcoversthedeterminationofthesteady-
fulfilled.
state thermal transmission properties of flat-slab specimens of
1.5 The specimens shall meet one of the following
thermalinsulationusingathinheaterofuniformpowerdensity
requirements, in addition to those of 1.4.
having low lateral heat flow. A thin heater with low lateral
1.5.1 If homogeneous materials as defined in Terminology
thermalconductancecanreduceunwantedlateralheatflowand
C168 are tested, then the thermal resistivity and thermal
avoid the need for active-edge guarding.
conductivity can be determined by this test method.
1.2 This primary test method of thermal-transmission mea-
1.5.2 If materials which are layered or otherwise thermally
surement describes a principle, rather than a particular appa-
inhomogeneous are tested, thermal resistance and thermal
ratus. The principle involves determination of the thermal flux
conductance can be determined by this test method.
across a specimen of known thickness and the temperatures of
1.6 Two versions of thin-heater apparatus using the same
the hot and cold faces of the specimen.
principleofthestandardaredescribedinAnnexA1andAnnex
1.3 Considerable latitude is given to the designer of the
A2. They are similar in concept but differ in size and
apparatus in this test method; since a variety of designs is
construction, and hence warrant separate descriptions for each
possible, a procedure for qualifying an apparatus is given in
design. This test method in no way limits the size of the
5.3.
thin-heater element. One of the units described uses a thin
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
of the heater must accurately represent the whole specimen.
materials,ifdesired.Thelarger,screenapparatusisdesignedto
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 ascer-
meet the prescribed requirements. Detailed information is
tainwhetherconditionsof1.4aresatisfied.Forthepurposesof
available in References (1-23) and the Adjunct.
1.8 The values stated in SI units are to be regarded as
standard. No other units of measurement are included in this
ThistestmethodisunderthejurisdictionofASTMCommitteeC16onThermal
Insulation and is the direct responsibility of Subcommittee C16.30 on Thermal standard.
Measurement.
1.9 This standard does not purport to address all of the
Current edition approved Sept. 1, 2013. Published January 2014. Originally
safety concerns, if any, associated with its use. It is the
approved 1989. Last previous edition approved 2006 as C1114–6. DOI: 10.1520/
C1114-06R13.
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
C1114 − 06 (2013)
responsibility of the user of this standard to establish appro- dimensional, longitudinal flow of heat perpendicular to the
priate safety and health practices and determine the applica- heater is obtained through the specimen. Because the foil or
bility of regulatory limitations prior to use. 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. Referenced Documents
guard, is unnecessary.
2.1 ASTM Standards:
5. Significance and Use
C168Terminology Relating to Thermal Insulation
C177Test Method for Steady-State Heat Flux Measure- 5.1 Factors that may influence the thermal-transmission
ments and Thermal Transmission Properties by Means of
properties of a specimen of material are described in Practice
the Guarded-Hot-Plate Apparatus C1045 and the Precision and Bias section of Test Method
C518Test Method for Steady-State Thermal Transmission
C177.
Properties by Means of the Heat Flow Meter Apparatus
5.2 Because of the required test conditions prescribed by
C687Practice for Determination of Thermal Resistance of
this test method, it shall be recognized that the thermal
Loose-Fill Building Insulation
properties obtained will not necessarily apply without modifi-
C1043Practice for Guarded-Hot-Plate Design Using Circu-
cation to all conditions of service. As an example, this test
lar Line-Heat Sources
method normally provides that the thermal properties shall be
C1044Practice for Using a Guarded-Hot-PlateApparatus or
obtained on specimens that do not contain moisture, although
Thin-Heater Apparatus in the Single-Sided Mode
in service such conditions may not be realized. Even more
C1045Practice for Calculating Thermal Transmission Prop-
basic is the dependence of the thermal properties on variables
erties Under Steady-State Conditions
such as mean temperature and temperature difference.
C1058Practice for Selecting Temperatures for Evaluating
5.3 Whenanewormodifieddesignofapparatusisevolved,
and Reporting Thermal Properties of Thermal Insulation
tests shall be made on at least two sets of differing material of
E177Practice for Use of the Terms Precision and Bias in
knownlong-termthermalstability.Testsshallbemadeforeach
ASTM Test Methods
material at a minimum of two different mean temperatures
2.2 ASTM Adjuncts:
5 within the operating range of each. Any differences in results
Descriptions of Two Types of Thin-Heater Apparatus
should be carefully studied to determine the cause and then be
removed by appropriate action. Only after a successful verifi-
3. Terminology
cation study on materials having known thermal properties
3.1 Applicable terms and symbols are defined in Terminol-
traceable to a recognized national standards laboratory shall
ogyC168.AnytermsorsymbolsnotincludedinC168butused
test results obtained with this apparatus be considered to
in this test method will be defined within the text.
conform with this test method. Periodic checks of apparatus
performance are recommended.
4. Summary of Test Method
5.4 The thermal transmission properties of many materials
4.1 Principles:
depend upon the prior thermal history. Care must be exercised
4.1.1 Athin-foil or metal-screen heating apparatus operates
when testing such specimens at a number of conditions so that
in accordance with the basic concept of a unidimensional,
testsareperformedinasequencethatlimitssucheffectsonthe
longitudinal heat-flow technique. The heater is made suffi-
results.
ciently thin so that lateral heat flow along the plane of the
heater is insignificant, and so that there is no need for isolation
5.5 Typical uses for the thin-heater apparatus include the
and separate temperature control of a guard region, except
following:
possibly the control of ambient temperature.
5.5.1 Product development and quality control applications.
4.1.2 The low mass of the thin heater apparatus minimizes
5.5.2 Measurement of thermal conductivity at desired mean
drift error and allows the apparatus to reach steady-state in a
temperatures.
significantly shorter time than a typical Test Method C177
5.5.3 Thermal properties of specimens that are moist or
apparatus.
close to melting point or other critical temperature (see Note
4.1.3 It should be noted that all quantities in this procedure
1).
are determined by direct measurement. There are no arbitrary
NOTE1—Apparatusofthetypecoveredbythistestmethodapplytothe
factors requiring calibration by comparison with a standard:
study of thermal properties of specimens containing moisture because of
thus, the apparatus yields results on an absolute basis.
the use of small temperature differences and the low thermal capacity of
4.1.4 Aproperly designed heater will be sufficiently thin to
the heat source.
reduce lateral heat flow from the central zone to an acceptably
5.5.4 Determination of thermal properties of relatively high
small level. The result is that within a central zone, one-
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
Standards volume information, refer to the standard’s Document Summary page on 6. Apparatus and Specimen Preparation
the ASTM website.
6.1 The simplicity of this test procedure may cause very
Available from ASTM International Headquarters. Order Adjunct No.
ADJC1114. important factors to be overlooked which may affect the
C1114 − 06 (2013)
results. To ensure accuracy of measurements, the user of this edge heat losses to below about 0.5%, the recommended
apparatusshouldknowhowtomeasuretemperatureandpower maximum thickness of the specimen is one third the minimum
as they relate to testing of thermal resistance. It is also
linear dimension of the metered region, if different from the
necessarythatthespecimensbeproperlyselectedandprepared thin-heater area. For more specific quantitative information on
for evaluation.
this limitation see Refs. (24), (25), (26), and (27).
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-
tained. Appropriate thermal modeling may allow tests of
7.2.2 Homogeneity— There are two potential problems in
nonuniform specimens, such as small specimens positioned
determining the heat flux through highly inhomogeneous
within larger ones, or composite or layered specimens.
specimens. One is related to the interpretation and application
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
the Specimen Preparation section of Test Method C177. from isothermal conditions which, in turn, can cause large
uncertainties in the average temperature difference across the
6.3.2 When evaluating compressible specimens, provide
means to maintain a definite, known test thickness. One specimen. The increased temperature variations of the thin
heater can also lead to increased edge heat losses. The
method is to insert rigid equal-length spacers made of low
thermal-conductivity material in the corners of specimens.An importance of measuring temperatures of the thin heater or
alternative method involves using mechanical arrangements to specimensurfaceatnumerouspointsisgreatlyincreasedunder
establishfixedandknownspacingandparallelismbetweenthe such conditions.
heater and cold plates.
7.3 Specimen Preparation and Installation—The specimen
6.3.3 The maximum allowable distance between the heater
shall be conditioned in accordance with the appropriate mate-
andcoldplates(specimenthickness)islimitedbythespecimen
rial specification. The following guidelines for specimen
thermal resistance, the ambient temperature, and the ratio of
preparationapplywhenthematerialspecificationisincomplete
measurement area to apparatus size. The isothermal area
or unavailable. In general, the surfaces of the specimen should
established in the center of the heater is influenced by these
be prepared to ensure uniform thermal contact with the thin
factors. The isothermal area must be large enough to establish
heater and the cooling plates.
the equilibrium heat flux (W/m ) through a representative area
7.3.1 Compressible Specimens—Also, for compressible
of the specimen. References are presented which will help
specimensthesurfacesoftheuncompressedspecimensmaybe
guide users in determining the maximum thickness that can be
comparatively rough so long as these undulations essentially
used for specimens in their apparatus.
vanish under test compression. Under more extreme
6.4 Thedistancebetweentheheaterandthecoldplatesmust
conditions, it may be necessary to smooth the specimen
beadjustedtoconfinethespecimenswithpressuresufficientto
surfaces to achieve better specimen contact. If the apparent
ensure good thermal contact between the specimens and the
thermal conductivity of the contact void is greater than
...
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