1、Designation: C1114 06 (Reapproved 2013)Standard Test Method forSteady-State Thermal Transmission Properties by Means ofthe Thin-Heater Apparatus1This standard is issued under the fixed designation C1114; the number immediately following the designation indicates the year oforiginal adoption or, in t
2、he case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the determination of the steady-state thermal transmission pr
3、operties of flat-slab specimens ofthermal insulation using a thin heater of uniform power densityhaving low lateral heat flow. A thin heater with low lateralthermal conductance can reduce unwanted lateral heat flow andavoid the need for active-edge guarding.1.2 This primary test method of thermal-tr
4、ansmission mea-surement describes a principle, rather than a particular appa-ratus. The principle involves determination of the thermal fluxacross a specimen of known thickness and the temperatures ofthe hot and cold faces of the specimen.1.3 Considerable latitude is given to the designer of theappa
5、ratus in this test method; since a variety of designs ispossible, a procedure for qualifying an apparatus is given in5.3.1.4 The specimens must meet the following conditions ifthermal resistance or thermal conductance of the specimen is tobe determined by this test method2:1.4.1 The portion of the s
6、pecimen over the isothermal areaof the heater must accurately represent the whole specimen.1.4.2 The remainder of the specimen should not distort theheat flow in that part of the specimen defined in 1.4.1.1.4.3 The specimen shall be thermally homogeneous suchthat the thermal conductivity is not a fu
7、nction of the positionwithin the sample, but rather may be a function of direction,time, and temperature. The specimen shall be free of holes, ofhigh-density volumes, and of thermal bridges between the testsurfaces or the specimen edges.1.4.4 Test Method C177 describes tests that can help ascer-tain
8、 whether conditions of 1.4 are satisfied. For the purposes ofthis test method, differences in the measurements of less than2 % may be considered insignificant, and the requirementsfulfilled.1.5 The specimens shall meet one of the followingrequirements, in addition to those of 1.4.1.5.1 If homogeneou
9、s materials as defined in TerminologyC168 are tested, then the thermal resistivity and thermalconductivity can be determined by this test method.1.5.2 If materials which are layered or otherwise thermallyinhomogeneous are tested, thermal resistance and thermalconductance can be determined by this te
10、st method.1.6 Two versions of thin-heater apparatus using the sameprinciple of the standard are described in AnnexA1 and AnnexA2. They are similar in concept but differ in size andconstruction, and hence warrant separate descriptions for eachdesign. This test method in no way limits the size of thet
11、hin-heater element. One of the units described uses a thinmetal foil, while the other uses a metal screen as the heatsource. The smaller, foil apparatus is designed to make rapidmeasurements of heat transmission through specimens as thinas 0.5 cm and as thick as 2 cm; however, an apparatus using afo
12、il heater could be designed to measure much thickermaterials, if desired. The larger, screen apparatus is designed tomeasure specimens with thicknesses between 3 and 15 cm,where the exact limits depend on the thermal resistance of thespecimens. Both apparatuses use thermocouples for measuringtempera
13、ture, but other temperature-sensing systems can beused.1.7 This test method covers the theory and principles of themeasurement technique. It does not provide details of construc-tion other than those required to illustrate two devices whichmeet the prescribed requirements. Detailed information isava
14、ilable in References (1-23)3and the Adjunct.1.8 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.9 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is the1This test method
15、 is under the jurisdiction ofASTM Committee C16 on ThermalInsulation and is the direct responsibility of Subcommittee C16.30 on ThermalMeasurement.Current edition approved Nov. 1, 2006. Published January 2014. Originallyapproved 1989. Last previous edition approved 2006 as C1114 6. DOI: 10.1520/C111
16、4-06R13.2Further discussion on the definition of these limitations may be found in Tye,R. P., “What Property Do We Measure?,” Heat Transmission Measurements inThermal Insulations, ASTM STP 544, ASTM, 1974, pp 512.3The boldface numbers in parentheses refer to the list of references at the end ofthis
17、test method.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1responsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. R
18、eferenced Documents2.1 ASTM Standards:4C168 Terminology Relating to Thermal InsulationC177 Test Method for Steady-State Heat Flux Measure-ments and Thermal Transmission Properties by Means ofthe Guarded-Hot-Plate ApparatusC518 Test Method for Steady-State Thermal TransmissionProperties by Means of t
19、he Heat Flow Meter ApparatusC687 Practice for Determination of Thermal Resistance ofLoose-Fill Building InsulationC1043 Practice for Guarded-Hot-Plate Design Using Circu-lar Line-Heat SourcesC1044 Practice for Using a Guarded-Hot-Plate Apparatus orThin-Heater Apparatus in the Single-Sided ModeC1045
20、Practice for Calculating Thermal Transmission Prop-erties Under Steady-State ConditionsC1058 Practice for Selecting Temperatures for Evaluatingand Reporting Thermal Properties of Thermal InsulationE177 Practice for Use of the Terms Precision and Bias inASTM Test Methods2.2 ASTM Adjuncts:Descriptions
21、 of Two Types of Thin-Heater Apparatus53. Terminology3.1 Applicable terms and symbols are defined in Terminol-ogy C168.Any terms or symbols not included in C168 but usedin this test method will be defined within the text.4. Summary of Test Method4.1 Principles:4.1.1 A thin-foil or metal-screen heati
22、ng apparatus operatesin accordance with the basic concept of a unidimensional,longitudinal heat-flow technique. The heater is made suffi-ciently thin so that lateral heat flow along the plane of theheater is insignificant, and so that there is no need for isolationand separate temperature control of
23、 a guard region, exceptpossibly the control of ambient temperature.4.1.2 The low mass of the thin heater apparatus minimizesdrift error and allows the apparatus to reach steady-state in asignificantly shorter time than a typical Test Method C177apparatus.4.1.3 It should be noted that all quantities
24、in this procedureare determined by direct measurement. There are no arbitraryfactors requiring calibration by comparison with a standard:thus, the apparatus yields results on an absolute basis.4.1.4 A properly designed heater will be sufficiently thin toreduce lateral heat flow from the central zone
25、 to an acceptablysmall level. The result is that within a central zone, one-dimensional, longitudinal flow of heat perpendicular to theheater is obtained through the specimen. Because the foil orscreen heater is very thin, the need for a gap between the innerand outer heater regions to act respectiv
26、ely as hot-plate andguard, is unnecessary.5. Significance and Use5.1 Factors that may influence the thermal-transmissionproperties of a specimen of material are described in PracticeC1045 and the Precision and Bias section of Test MethodC177.5.2 Because of the required test conditions prescribed byt
27、his test method, it shall be recognized that the thermalproperties obtained will not necessarily apply without modifi-cation to all conditions of service. As an example, this testmethod normally provides that the thermal properties shall beobtained on specimens that do not contain moisture, although
28、in service such conditions may not be realized. Even morebasic is the dependence of the thermal properties on variablessuch 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 ofknown
29、long-term thermal stability. Tests shall be made for eachmaterial at a minimum of two different mean temperatureswithin the operating range of each. Any differences in resultsshould be carefully studied to determine the cause and then beremoved by appropriate action. Only after a successful verifi-c
30、ation study on materials having known thermal propertiestraceable to a recognized national standards laboratory shalltest results obtained with this apparatus be considered toconform with this test method. Periodic checks of apparatusperformance are recommended.5.4 The thermal transmission propertie
31、s of many materialsdepend upon the prior thermal history. Care must be exercisedwhen testing such specimens at a number of conditions so thattests are performed in a sequence that limits such effects on theresults.5.5 Typical uses for the thin-heater apparatus include thefollowing:5.5.1 Product deve
32、lopment and quality control applications.5.5.2 Measurement of thermal conductivity at desired meantemperatures.5.5.3 Thermal properties of specimens that are moist orclose to melting point or other critical temperature (see Note1).NOTE 1Apparatus of the type covered by this test method apply to thes
33、tudy of thermal properties of specimens containing moisture because ofthe use of small temperature differences and the low thermal capacity ofthe heat source.5.5.4 Determination of thermal properties of relatively highR value insulation samples with large apparatuses. In the caseof the metal-screen
34、heater apparatus, samples with thicknessesup to 15 cm can be measured.6. Apparatus and Specimen Preparation6.1 The simplicity of this test procedure may cause veryimportant factors to be overlooked which may affect the4For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact AS
35、TM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.5Available from ASTM International Headquarters. Order Adjunct No.ADJC1114.C1114 06 (2013)2results. To ensure accuracy of measurements, the use
36、r of thisapparatus should know how to measure temperature and poweras they relate to testing of thermal resistance. It is alsonecessary that the specimens be properly selected and preparedfor evaluation.6.2 Normally, test specimens are selected in pairs from thesample lot. The specimens selected sho
37、uld be uniform andhomogeneous to ensure that test apparatus symmetry is main-tained. Appropriate thermal modeling may allow tests ofnonuniform specimens, such as small specimens positionedwithin larger ones, or composite or layered specimens.6.3 Test specimens shall be prepared and conditioned inacc
38、ordance with the appropriate material specification. Theconditioning of the test specimens shall be reported.6.3.1 The surfaces of the specimens shall be prepared toensure uniform thermal contact with the heater andtemperature-controlled plates. Further details may be found inthe Specimen Preparatio
39、n section of Test Method C177.6.3.2 When evaluating compressible specimens, providemeans to maintain a definite, known test thickness. Onemethod is to insert rigid equal-length spacers made of lowthermal-conductivity material in the corners of specimens. Analternative method involves using mechanica
40、l arrangements toestablish fixed and known spacing and parallelism between theheater and cold plates.6.3.3 The maximum allowable distance between the heaterand cold plates (specimen thickness) is limited by the specimenthermal resistance, the ambient temperature, and the ratio ofmeasurement area to
41、apparatus size. The isothermal areaestablished in the center of the heater is influenced by thesefactors. The isothermal area must be large enough to establishthe equilibrium heat flux (W/m2) through a representative areaof the specimen. References are presented which will helpguide users in determi
42、ning the maximum thickness that can beused for specimens in their apparatus.6.4 The distance between the heater and the cold plates mustbe adjusted to confine the specimens with pressure sufficient toensure good thermal contact between the specimens and thebounding surfaces. For rigid specimens, a p
43、ressure of 2.5 kPais recommended. For compressible specimens, see 6.3.2.7. Procedure7.1 The testing procedure includes the following steps:7.1.1 Specimen selection,7.1.2 Specimen preparation and installation, and7.1.3 Test execution.7.2 Specimen SelectionOnly those specimen selection fac-tors import
44、ant to the performance of the apparatus are consid-ered here. Those factors dictated by the objectives related toobtaining derived thermal properties are described in PracticeC1045 and material specifications. For the two-sided mode ofoperation, the two specimens should be selected to be assimilar i
45、n thickness and thermal characteristics as possible.7.2.1 SizeThe maximum specimen thickness that can bemeasured to a given accuracy is dependent on severalparameters, including the size of the apparatus, thermal resis-tance of the specimen, and the accuracy desired. To maintainedge heat losses to b
46、elow about 0.5 %, the recommendedmaximum thickness of the specimen is one third the minimumlinear dimension of the metered region, if different from thethin-heater area. For more specific quantitative information onthis limitation see Refs. (24), (25), (26), and (27).7.2.1.1 The specimen may be size
47、d to extend beyond themetered area by a distance sufficient to ensure one-dimensionalheat flow within the metered area.7.2.2 Homogeneity There are two potential problems indetermining the heat flux through highly inhomogeneousspecimens. One is related to the interpretation and applicationof the resu
48、lting data; it is discussed in Practice C1045. Theother is connected with the degradation in performance of theapparatus. If the specimen itself is highly inhomogeneous, thatis, the heat flux density varies appreciably over the meteredarea, several errors can be significantly increased. The tem-pera
49、ture distribution of the thin heater can deviate appreciablyfrom isothermal conditions which, in turn, can cause largeuncertainties in the average temperature difference across thespecimen. The increased temperature variations of the thinheater can also lead to increased edge heat losses. Theimportance of measuring temperatures of the thin heater orspecimen surface at numerous points is greatly increased undersuch conditions.7.3 Specimen Preparation and InstallationThe specimenshall be conditioned in accordance with the appropriate mate-rial specification. The following guidel
