1、Designation: C518 15C518 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 o
2、f 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.This standard has been approved for use by agencies of the U.S. Department of Defense.1. Scope1.1 This tes
3、t method covers the measurement of steady state thermal transmission through flat slab specimens using a heat flowmeter apparatus.1.2 The heat flow meter apparatus is used widely because it is relatively simple in concept, rapid, and applicable to a wide rangeof test specimens.The precision and bias
4、 of the heat flow meter apparatus can be excellent provided calibration is carried out withinthe range of heat flows expected. This means calibration shall be carried out with similar types of materials, of similar thermalconductances, at similar thicknesses, mean temperatures, and temperature gradi
5、ents, as expected for the test specimens.1.3 This a comparative, or secondary, method of measurement since specimens of known thermal transmission properties shallbe used to calibrate the apparatus. Properties of the calibration specimens must be traceable to an absolute measurement method.The calib
6、ration specimens should be obtained from a recognized national standards laboratory.1.4 The heat flow meter apparatus establishes steady state one-dimensional heat flux through a test specimen between twoparallel plates at constant but different temperatures. By appropriate calibration of the heat f
7、lux transducer(s) with calibrationstandards and by measurement of the plate temperatures and plate separation. Fouriers law of heat conduction is used to calculatethermal conductivity, and thermal resistivity or thermal resistance and thermal conductance.1.5 This test method shall be used in conjunc
8、tion with Practice C1045. Many advances have been made in thermal technology,both in measurement techniques and in improved understanding of the principles of heat flow through materials. These advanceshave prompted revisions in the conceptual approaches to the measurement of the thermal transmissio
9、n properties (1-4).2 All usersof this test method should be aware of these concepts.1.6 This test method is applicable to the measurement of thermal transmission through a wide range of specimen properties andenvironmental conditions. The method has been used at ambient conditions of 10 to 40C with
10、thicknesses up to approximately250 mm, and with plate temperatures from 195C to 540C at 25-mm thickness (5, 6).1.7 This test method may be used to characterize material properties, which may or may not be representative of actualconditions of use. Other test methods, such as Test Methods C236 or C97
11、6 should be used if needed.1.8 To meet the requirements of this test method the thermal resistance of the test specimen shall be greater than 0.10 m2K/Win the direction of the heat flow and edge heat losses shall be controlled, using edge insulation, or a guard heater, or both.1.9 It is not practica
12、l in a test method of this type to try to establish details of construction and procedures to cover allcontingencies that might offer difficulties to a person without pertinent technical knowledge. Thus users of this test method shallhave sufficient knowledge to satisfactorily fulfill their needs. F
13、or example, knowledge of heat transfer principles, low levelelectrical measurements, and general test procedures is required.1.10 The user of this method must be familiar with and understand the Annex. The Annex is critically important in addressingequipment design and error analysis.1.11 Standardiz
14、ation of this test method is not intended to restrict in any way the future development of improved or newmethods or procedures by research workers.1 This test method is under the jurisdiction of ASTM Committee C16 on Thermal Insulation and is the direct responsibility of Subcommittee C16.30 on Ther
15、malMeasurement.Current edition approved Sept. 1, 2015May 1, 2017. Published December 2015July 2017. Originally approved in 1963. Last previous edition approved in 20102015 asC518C518 15. 10. DOI: 10.1520/C0518-15.10.1520/C0518-17.2 The boldface numbers in parentheses refer to the list of references
16、at the end of this test method.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommen
17、ds that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States11.12 Since the de
18、sign of a heat flow meter apparatus is not a simple matter, a procedure for proving the performance of anapparatus is given in Appendix X3.1.13 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.14 This standard does not purpor
19、t to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to consult and establish appropriate safety and health practices and determine the applicability ofregulatory limitations prior to use.1.15 This international standard was d
20、eveloped in accordance with internationally recognized principles on standardizationestablished in the Decision on Principles for the Development of International Standards, Guides and Recommendations issuedby the World Trade Organization Technical Barriers to Trade (TBT) Committee.2. Referenced Doc
21、uments2.1 ASTM Standards:3C167 Test Methods for Thickness and Density of Blanket or Batt Thermal InsulationsC168 Terminology Relating to Thermal InsulationC177 Test Method for Steady-State Heat Flux Measurements and Thermal Transmission Properties by Means of theGuarded-Hot-Plate ApparatusC236 Test
22、Method for Steady-State Thermal Performance of BuildingAssemblies by Means of a Guarded Hot Box (Withdrawn2001)4C687 Practice for Determination of Thermal Resistance of Loose-Fill Building InsulationC976 Test Method for Thermal Performance of Building Assemblies by Means of a Calibrated Hot Box (Wit
23、hdrawn 2002)4C1045 Practice for Calculating Thermal Transmission Properties Under Steady-State ConditionsC1046 Practice for In-Situ Measurement of Heat Flux and Temperature on Building Envelope ComponentsC1058 Practice for Selecting Temperatures for Evaluating and Reporting Thermal Properties of The
24、rmal InsulationC1114 Test Method for Steady-State Thermal Transmission Properties by Means of the Thin-Heater ApparatusE230/E230M Specification for Temperature-Electromotive Force (emf) Tables for Standardized ThermocouplesE178 Practice for Dealing With Outlying ObservationsE456 Terminology Relating
25、 to Quality and StatisticsE691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method2.2 ISO Standard:ISO 8301:1991 Thermal InsulationDetermination of Steady-State Thermal Resistance and Related PropertiesHeat FlowMeter Apparatus53. Terminology3.1 DefinitionsFor
26、 definitions of terms and symbols used in this test method, refer to Terminology C168 and to the followingsubsections.3.2 Definitions of Terms Specific to This Standard:3.2.1 calibration, nthe process of establishing the calibration factor for a particular apparatus using calibration specimenshaving
27、 known thermal transmission properties.3.2.2 calibration transfer specimen, n(CTS) a thermal calibration specimen that has been measured by a national standardslaboratory (7).3.2.3 cold surface assembly, nthe plate that provides as isothermal boundary at the cold surface of the test specimen(s).3.2.
28、4 controlled environment, nan environment sometimes employed in the apparatus to limit lateral heat flows.3.2.5 edge insulation, nauxiliary insulation used to limit lateral heat flows, these are sometimes permanently mounted in theapparatus.3.2.6 guard, npromotes one-dimensional heat flow. Primary g
29、uards are planar, additional coplanar guards can be used andsecondary or edge guards are axial.3.2.7 heat flow meter apparatus, nthe complete assemblage of the instrument, including hot and cold isothermal surfaces, theheat flux transducer(s), and the controlled environment if used, and instrumentat
30、ion to indicate hot and cold surface temperatures,specimen thickness, and heat flux.3.2.8 hot surface assembly, nthe plate that provides an isothermal boundary at the hot surface of the test specimen(s).3 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Serv
31、ice at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.4 The last approved version of this historical standard is referenced on www.astm.org.5 Available from American National Standards Institute (ANSI), 25 W. 43r
32、d St., 4th Floor, New York, NY 10036, http:/www.ansi.org.C518 1723.2.9 heat flux transducer, na device containing a thermopile, or an equivalent, that produces an output which is a functionof the heat flux passing through it. The metering area usually consists of a number of differently connected te
33、mperature sensorsplaced on each face of a core and surface sheets to protect the assembly. A properly designed transducer will have a sensitivitythat is essentially independent of the thermal properties of the specimen.3.2.10 metering area, nthe area of the specimen(s) in contact with the sensor are
34、a of the heat flux transducer.3.2.11 secondary transfer standard, na specimen, which has been measured in a heat flow meter apparatus, which has beencalibrated with primary standards, used to calibrate additional apparatuses.3.2.12 sensitivity, nthe ratio of the heat flux passing through the transdu
35、cer to the electrical output of the heat flux transducer.3.2.13 standard reference material (SRM), na lot of material that has been characterized by a national standards laboratory(7).3.2.14 thermal transmission properties, nthose properties of a material or system that define the ability of the mat
36、erial orsystem to transfer heat. Properties, such as thermal resistance, thermal conductance, thermal conductivity, and thermal resistivitywould be included, as defined in Terminology C168.3.3 Symbols and UnitsThe symbols used in this test method have the following significance:3.3.1 thermal conduct
37、ivity, 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 between the hot and cold plate assemblies during testing, m.3.3.8 Tmm
38、ean 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 transducer output, V.3.3.13 Thtemperature of the hot plate surface, K.3.3.14 Tct
39、emperature 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 method provides a rapid means of determining the steady-state thermal transmissio
40、n properties of thermalinsulations and other materials with a high level of accuracy when the apparatus has been calibrated appropriately.4.2 Proper calibration of the heat flow meter apparatus requires that it be calibrated using specimen(s) having thermaltransmission properties determined previous
41、ly by Test Methods C177, or C1114.NOTE 1Calibration of the apparatus typically requires specimens that are similar to the types of materials, thermal conductances, thicknesses, meantemperatures, and temperature gradients as expected for the test specimens.4.3 The thermal transmission properties of s
42、pecimens of a given material or product may vary due to variability of thecomposition of the material; be affected by moisture or other conditions; change with time; change with mean temperature andtemperature difference; and depend upon the prior thermal history. It must be recognized, therefore, t
43、hat the selection of typicalvalues of thermal transmission properties representative of a material in a particular application should be based on a considerationof these factors and will not apply necessarily without modification to all service conditions.4.3.1 As an example, this test method provid
44、es that the thermal properties shall be obtained on specimens that do not containany free moisture although in service such conditions may not be realized. Even more basic is the dependence of the thermalproperties on variables, such as mean temperature and temperature difference. These dependencies
45、 should be measured or the testmade at conditions typical of use.4.4 Special care shall be taken in the measurement procedure for specimens exhibiting appreciable inhomogeneities,anisotropies, rigidity, or especially high or low resistance to heat flow (see Practice C1045). The use of a heat flow me
46、ter apparatuswhen there are thermal bridges present in the specimen may yield very unreliable results. If the thermal bridge is present andparallel to the heat flow the results obtained may well have no meaning. Special considerations also are necessary when theC518 173measurements are conducted at
47、either high or low temperatures, in ambient pressures above or below atmospheric pressure, or inspecial ambient gases that are inert or hazardous.4.5 The determination of the accuracy of the method for any given test is a function of the apparatus design, of the relatedinstrumentation, and of the ty
48、pe of specimens under test (see Section 10), but this test method is capable of determining thermaltransmission properties within 6 2 % of those determined by Test Method C177 when the ambient temperature is near the meantemperature of the test (T (ambient) = T (mean) 6 1C), and in the range of 10 t
49、o 40C. In all cases the accuracy of the heat flowmeter apparatus can never be better than the accuracy of the primary standards used to calibrate the apparatus.4.5.1 When this test method is to be used for certification testing of products, the apparatus shall have the capabilities requiredin A1.7 and one of the following procedures shall be followed:4.5.1.1 The apparatus shall have its calibration checked within 24 h before or after a certification test using either secondarytransfer standards traceable to, or calibration s
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