ASTM_C_518_-_17.pdf

Designation:C51817Standard 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 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 test method 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 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 expected 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 specimens 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 transducer(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 withPractice 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(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 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 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 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 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 method 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 under 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/C0518-17.2The 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 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.1 1.13 The values stated in SI