1、Designation: C 518 04Standard Test Method forSteady-State Thermal Transmission Properties by Means ofthe Heat Flow Meter Apparatus1This standard is issued under the fixed designation C 518; the number immediately following the designation indicates the year oforiginal adoption or, in the case of rev
2、ision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defense.1. Scope1.1 This test method
3、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 he
4、at 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 expe
5、cted 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 spe
6、cimens 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 transdu
7、cer(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 withPr
8、actice C 1045. 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 MethodsC 236 or C 976 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
12、of 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
13、of 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 metho
14、d 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 u
15、nder the jurisdiction ofASTM Committee C16 on ThermalInsulation and is the direct responsibility of Subcommittee C16.30 on ThermalMeasurement.Current edition approved May 1, 2004. Published June 2004. Originallyapproved in 1963. Last previous edition approved in 2002 as C 518 02e1.2The boldface numb
16、ers in parentheses refer to the list of references at the end ofthis test method.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.1.13 This standard does not purport to address all of thesafety concerns, if any, associated with its us
17、e. It is theresponsibility of the user of this standard to consult andestablish appropriate safety and health practices and deter-mine the applicability of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:3C 167 Test Methods for Thickness and Density of Blanketor Batt Th
18、ermal InsulationsC 168 Terminology Relating to Thermal InsulationC 177 Test Method for Steady-State Heat Flux Measure-ments and Thermal Transmission Properties by Means ofthe Guarded Hot Plate ApparatusC 236 Test Method for Steady-State Thermal Performanceof Building Assemblies by Means of a Guarded
19、 Hot BoxC 687 Practice for Determination of the Thermal Resistanceof Loose-Fill Building InsulationC 976 Test Method for Thermal Performance of BuildingAssemblies by Means of a Calibrated Hot BoxC 1045 Practice for Calculating Thermal TransmissionProperties Under Steady-State ConditionsC 1046 Practi
20、ce for In-Situ Measurement of Heat Flux andTemperature on Building Envelope ComponentsC 1058 Practice for Selecting Temperatures for Evaluatingand Reporting Thermal Properties of Thermal InsulationC 1114 Test Method for Steady-State Thermal TransmissionProperties by Means of the Thin-Heater Apparatu
21、sC 1363 Test Method for the Thermal Performance of Build-ing Assemblies by Means of a Hot Box ApparatusE 230 Specification and Temperature-Electromotive Force(EMF) Tables for Standardized ThermocouplesE 178 Practice for Dealing with Outlying ObservationsE 691 Practice for Conducting an Interlaborato
22、ry Study toDetermine the Precision of a Test Method2.2 ISO Standard:ISO 8301:1991 Thermal InsulationDetermination ofSteady-State Thermal Resistance and RelatedPropertiesHeat Flow Meter Apparatus43. Terminology3.1 DefinitionsFor definitions of terms and symbols usedin this test method, refer to Termi
23、nology C 168 and to thefollowing subsections.3.2 Definitions of Terms Specific to This Standard:3.2.1 calibration, nthe process of establishing the calibra-tion factor for a particular apparatus using calibration speci-mens having known thermal transmission properties.3.2.2 calibration transfer spec
24、imen, n(CTS) a thermalcalibration specimen that has been measured by a nationalstandards laboratory (26).3.2.3 cold surface assembly, nthe plate 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 ap
25、paratus to limit lateral heat flows.3.2.5 edge insulation, nauxiliary insulation used to limitlateral heat flows, these are sometimes permanently mounted inthe apparatus.3.2.6 guard, npromotes one-dimensional heat flow. Pri-mary guards are planar, additional coplanar guards can be usedand secondary
26、or edge guards are axial.3.2.7 heat flow meter apparatus, nthe complete assem-blage of the instrument, including hot and cold isothermalsurfaces, the heat flux transducer(s), and the controlled envi-ronment if used, and instrumentation to indicate hot and coldsurface temperatures, specimen thickness
27、, 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 heat flux transducer, na device containing a ther-mopile, or an equivalent, that produces an output which is afunction of the heat flux passing through it. The
28、metering areausually consists of a number of differently connected tempera-ture sensors placed on each face of a core and surface sheets toprotect the assembly. A properly designed transducer will havea sensitivity that is essentially independent of the thermalproperties of the specimen.3.2.10 meter
29、ing area, nthe area of the specimen(s) incontact with the sensor area of the heat flux transducer.3.2.11 secondary transfer standard, na specimen, whichhas been measured in a heat flow meter apparatus, which hasbeen calibrated with primary standards, used to calibrateadditional apparatuses.3.2.12 se
30、nsitivity, nthe ratio of the heat flux passingthrough the transducer to the electrical output of the heat fluxtransducer.3.2.13 standard reference material (SRM), na lot ofmaterial that has been characterized by a national standardslaboratory (26).3.2.14 thermal transmission properties, nthose prope
31、rtiesof a material or system that define the ability of the material orsystem to transfer heat. Properties, such as thermal resistance,thermal conductance, thermal conductivity, and thermal resis-tivity would be included, as defined in Terminology C 168.3.3 Symbols and UnitsThe symbols used in this
32、testmethod have the following significance:3.3.1 lthermal 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 Lseparation betw
33、een the hot and cold plate assem-blies during testing, m.3.3.8 Tmmean temperature, (Th+Tc)/2, K.3.3.9 DTtemperature difference across the specimen, K.3.3.10 r(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 transducer outp
34、ut, V.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 standards Document Summary page onthe ASTM website.4Available from American National Standards Institute (
35、ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036.C5180423.3.13 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 astatistical term used to define significance level
36、.4. Significance and Use4.1 This test method 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
37、 apparatusrequires that it be calibrated using specimen(s) having thermaltransmission properties determined previously by Test Meth-ods C 177,orC 1114.NOTE 1Calibration of the apparatus typically requires specimens thatare similar to the types of materials, thermal conductances, thicknesses,mean tem
38、peratures, and temperature gradients as expected 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 temp
39、eratureand temperature difference; and depend 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 no
40、t apply necessarilywithout modification to all 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
41、 thethermal properties on variables, such as 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,anisotropie
42、s, rigidity, or especially high or low resistance toheat flow (see Practice C 1045). 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 we
43、ll have no meaning. Special considerationsalso 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
44、anygiven test is a function of the apparatus design, 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 C 177 when the ambient temperatu
45、re isnear the mean temperature of the test (T (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
46、 certificationtesting of products, the apparatus 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 traceabl
47、e 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 average value. When
48、the change in calibration factor isgreater than 1 %, the standard specimen shall be retested and anew average calculated. If the change in calibration factor isstill greater than 1 % the apparatus shall be calibrated using theprocedure in Section 6.4.5.1.2 Where both the short and long term stabilit
49、y of theapparatus have been proven to be better than 1 % of the reading(see Section 10), the apparatus may be calibrated at lessfrequent intervals, not exceeding 30 days. The specimens sotested cannot be certified until after the calibration test follow-ing the test and then only if the change in calibration factorfrom the previous calibration test is less than 1 %. When thechange in calibration is greater than 1 %, test results from thisinterval shall be considered void and the tests repeated inaccordance with 4.5.1.1.4.5.2 The precisi
