1、Designation: C518 17Standard Test Method forSteady-State Thermal Transmission Properties by Means ofthe Heat Flow Meter Apparatus1This standard is issued under the fixed designation C518; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revis
2、ion, 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.This standard has been approved for use by agencies of the U.S. Department of Defense.1. Scope1.1 This test metho
3、d covers the measurement of steady statethermal transmission through flat slab specimens using a heatflow meter apparatus.1.2 The heat flow meter apparatus is used widely because itis relatively simple in concept, rapid, and applicable to a widerange of test specimens. The precision and bias of the
4、heat flowmeter apparatus can be excellent provided calibration is carriedout within the range of heat flows expected. This meanscalibration shall be carried out with similar types of materials,of similar thermal conductances, at similar thicknesses, meantemperatures, and temperature gradients, as ex
5、pected for thetest specimens.1.3 This a comparative, or secondary, method of measure-ment since specimens of known thermal transmission proper-ties shall be used to calibrate the apparatus. Properties of thecalibration specimens must be traceable to an absolute mea-surement method. The calibration s
6、pecimens should be ob-tained from a recognized national standards laboratory.1.4 The heat flow meter apparatus establishes steady stateone-dimensional heat flux through a test specimen between twoparallel plates at constant but different temperatures. Byappropriate calibration of the heat flux trans
7、ducer(s) withcalibration standards and by measurement of the plate tempera-tures and plate separation. Fouriers law of heat conduction isused to calculate thermal conductivity, and thermal resistivityor thermal resistance and thermal conductance.1.5 This test method shall be used in conjunction with
8、Practice C1045. Many advances have been made in thermaltechnology, both in measurement techniques and in improvedunderstanding of the principles of heat flow through materials.These advances have prompted revisions in the conceptualapproaches to the measurement of the thermal transmissionproperties
9、(1-4).2All users of this test method should be awareof these concepts.1.6 This test method is applicable to the measurement ofthermal transmission through a wide range of specimen prop-erties and environmental conditions. The method has been usedat ambient conditions of 10 to 40C with thicknesses up
10、 toapproximately 250 mm, and with plate temperatures from195C to 540C at 25-mm thickness (5, 6).1.7 This test method may be used to characterize materialproperties, which may or may not be representative of actualconditions of use. Other test methods, such as Test MethodsC236 or C976 should be used
11、if needed.1.8 To meet the requirements of this test method the thermalresistance of the test specimen shall be greater than 0.10m2K/W in the direction of the heat flow and edge heat lossesshall be controlled, using edge insulation, or a guard heater, orboth.1.9 It is not practical in a test method o
12、f this type to try toestablish details of construction and procedures to cover allcontingencies that might offer difficulties to a person withoutpertinent technical knowledge. Thus users of this test methodshall have sufficient knowledge to satisfactorily fulfill theirneeds. For example, knowledge o
13、f heat transfer principles, lowlevel electrical measurements, and general test procedures isrequired.1.10 The user of this method must be familiar with andunderstand the Annex. The Annex is critically important inaddressing equipment design and error analysis.1.11 Standardization of this test method
14、 is not intended torestrict in any way the future development of improved or newmethods or procedures by research workers.1.12 Since the design of a heat flow meter apparatus is nota simple matter, a procedure for proving the performance of anapparatus is given in Appendix X3.1This test method is un
15、der the jurisdiction ofASTM Committee C16 on ThermalInsulation and is the direct responsibility of Subcommittee C16.30 on ThermalMeasurement.Current edition approved May 1, 2017. Published July 2017. Originally approvedin 1963. Last previous edition approved in 2015 as C518 15. DOI: 10.1520/C0518-17
16、.2The boldface numbers in parentheses refer to the list of references at the end ofthis test method.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized
17、 principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.11.13 The values stated in SI units are to be regarded asstandard. No
18、other units of measurement are included in thisstandard.1.14 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to consult andestablish appropriate safety and health practices and deter-mine the a
19、pplicability of regulatory limitations prior to use.1.15 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued
20、 by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:3C167 Test Methods for Thickness and Density of Blanket orBatt Thermal InsulationsC168 Terminology Relating to Thermal InsulationC177 Test Method for Steady-State Heat Flux Measure-m
21、ents and Thermal Transmission Properties by Means ofthe Guarded-Hot-Plate ApparatusC236 Test Method for Steady-State Thermal Performance ofBuilding Assemblies by Means of a Guarded Hot Box(Withdrawn 2001)4C687 Practice for Determination of Thermal Resistance ofLoose-Fill Building InsulationC976 Test
22、 Method for Thermal Performance of BuildingAssemblies by Means of a Calibrated Hot Box (With-drawn 2002)4C1045 Practice for Calculating Thermal Transmission Prop-erties Under Steady-State ConditionsC1046 Practice for In-Situ Measurement of Heat Flux andTemperature on Building Envelope ComponentsC105
23、8 Practice for Selecting Temperatures for Evaluatingand Reporting Thermal Properties of Thermal InsulationC1114 Test Method for Steady-State Thermal TransmissionProperties by Means of the Thin-Heater ApparatusE230/E230M Specification for Temperature-ElectromotiveForce (emf) Tables for Standardized T
24、hermocouplesE178 Practice for Dealing With Outlying ObservationsE456 Terminology Relating to Quality and StatisticsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method2.2 ISO Standard:ISO 8301:1991 Thermal InsulationDetermination ofSteady-State Thermal Res
25、istance and RelatedPropertiesHeat Flow Meter Apparatus53. Terminology3.1 DefinitionsFor definitions of terms and symbols usedin this test method, refer to Terminology C168 and to thefollowing subsections.3.2 Definitions of Terms Specific to This Standard:3.2.1 calibration, nthe process of establishi
26、ng the calibra-tion factor for a particular apparatus using calibration speci-mens having known thermal transmission properties.3.2.2 calibration transfer specimen, n(CTS) a thermalcalibration specimen that has been measured by a nationalstandards laboratory (7).3.2.3 cold surface assembly, nthe pla
27、te that provides asisothermal boundary at the cold surface of the test specimen(s).3.2.4 controlled environment, nan environment some-times employed in the apparatus to limit lateral heat flows.3.2.5 edge insulation, nauxiliary insulation used to limitlateral heat flows, these are sometimes permanen
28、tly mounted inthe apparatus.3.2.6 guard, npromotes one-dimensional heat flow. Pri-mary guards are planar, additional coplanar guards can be usedand secondary or edge guards are axial.3.2.7 heat flow meter apparatus, nthe complete assem-blage of the instrument, including hot and cold isothermalsurfac
29、es, the heat flux transducer(s), and the controlled envi-ronment if used, and instrumentation to indicate hot and coldsurface temperatures, specimen thickness, and heat flux.3.2.8 hot surface assembly, nthe plate that provides anisothermal boundary at the hot surface of the test specimen(s).3.2.9 he
30、at flux transducer, na device containing athermopile, or an equivalent, that produces an output which isa function of the heat flux passing through it. The metering areausually consists of a number of differently connected tempera-ture sensors placed on each face of a core and surface sheets toprote
31、ct the assembly. A properly designed transducer will havea sensitivity that is essentially independent of the thermalproperties of the specimen.3.2.10 metering area, nthe area of the specimen(s) incontact with the sensor area of the heat flux transducer.3.2.11 secondary transfer standard, na specime
32、n, whichhas been measured in a heat flow meter apparatus, which hasbeen calibrated with primary standards, used to calibrateadditional apparatuses.3.2.12 sensitivity, nthe ratio of the heat flux passingthrough the transducer to the electrical output of the heat fluxtransducer.3.2.13 standard referen
33、ce material (SRM), na lot of ma-terial that has been characterized by a national standardslaboratory (7).3.2.14 thermal transmission properties, nthose propertiesof a material or system that define the ability of the material orsystem to transfer heat. Properties, such as thermal resistance,thermal
34、conductance, thermal conductivity, and thermal resis-tivity would be included, as defined in Terminology C168.3For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the st
35、andards Document Summary page onthe ASTM website.4The last approved version of this historical standard is referenced onwww.astm.org.5Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036, http:/www.ansi.org.C518 1723.3 Symbols and UnitsThe symbols
36、 used in this testmethod have the following significance:3.3.1 thermal conductivity, W/(mK).3.3.2 Cthermal conductance, W/(m2K)3.3.3 Rthermal resistance, (m2K)/W.3.3.4 qheat flux (heat flow rate, Q, through area A), W/m2.3.3.5 Qheat flow rate in the metered area, W.3.3.6 Ametering area, m2.3.3.7 Lse
37、paration between the hot and cold plate assem-blies during testing, m.3.3.8 Tmmean temperature, (Th+Tc)/2, K.3.3.9 Ttemperature difference across the specimen, K.3.3.10 (bulk) density of the material tested, kg/m3.3.3.11 Scalibration factor of the heat flux transducer,(W/m2)/V.3.3.12 Eheat flux tran
38、sducer output, V.3.3.13 Thtemperature of the hot plate surface, K.3.3.14 Tctemperature of the cold plate surface, K.3.4 Subscripts:3.4.1 hhot.3.4.2 ccold3.4.3 a, bfirst and second specimen.3.4.4 mmean.3.4.5 statistical term used to define significance level.4. Significance and Use4.1 This test metho
39、d provides a rapid means of determiningthe steady-state thermal transmission properties of thermalinsulations and other materials with a high level of accuracywhen the apparatus has been calibrated appropriately.4.2 Proper calibration of the heat flow meter apparatusrequires that it be calibrated us
40、ing specimen(s) having thermaltransmission properties determined previously by Test Meth-ods C177,orC1114.NOTE 1Calibration of the apparatus typically requires specimens thatare similar to the types of materials, thermal conductances, thicknesses,mean temperatures, and temperature gradients as expec
41、ted for the testspecimens.4.3 The thermal transmission properties of specimens of agiven material or product may vary due to variability of thecomposition of the material; be affected by moisture or otherconditions; change with time; change with mean temperatureand temperature difference; and depend
42、 upon the prior thermalhistory. It must be recognized, therefore, that the selection oftypical values of thermal transmission properties representativeof a material in a particular application should be based on aconsideration of these factors and will not apply necessarilywithout modification to al
43、l service conditions.4.3.1 As an example, this test method provides that thethermal properties shall be obtained on specimens that do notcontain any free moisture although in service such conditionsmay not be realized. Even more basic is the dependence of thethermal properties on variables, such as
44、mean temperature andtemperature difference. These dependencies should be mea-sured or the test made at conditions typical of use.4.4 Special care shall be taken in the measurement proce-dure for specimens exhibiting appreciable inhomogeneities,anisotropies, rigidity, or especially high or low resist
45、ance toheat flow (see Practice C1045). The use of a heat flow meterapparatus when there are thermal bridges present in thespecimen may yield very unreliable results. If the thermalbridge is present and parallel to the heat flow the resultsobtained may well have no meaning. Special considerationsalso
46、 are necessary when the measurements are conducted ateither high or low temperatures, in ambient pressures above orbelow atmospheric pressure, or in special ambient gases thatare inert or hazardous.4.5 The determination of the accuracy of the method for anygiven test is a function of the apparatus d
47、esign, of the relatedinstrumentation, and of the type of specimens under test (seeSection 10), but this test method is capable of determiningthermal transmission properties within 6 2 % of those deter-mined by Test Method C177 when the ambient temperature isnear the mean temperature of the test (T (
48、ambient) = T (mean)6 1C), and in the range of 10 to 40C. In all cases theaccuracy of the heat flow meter apparatus can never be betterthan the accuracy of the primary standards used to calibrate theapparatus.4.5.1 When this test method is to be used for certificationtesting of products, the apparatu
49、s shall have the capabilitiesrequired in A1.7 and one of the following procedures shall befollowed:4.5.1.1 The apparatus shall have its calibration checkedwithin 24 h before or after a certification test using eithersecondary transfer standards traceable to, or calibration stan-dards whose values have been established by, a recognizednational standards laboratory not more than five years prior tothe certification date. The average of two calibrations shall beused as the calibration factor and the specimen(s) certified withthis av
