1、Designation:C16817Standard Terminology Relating toThermal Insulation1This standard is issued under the fixed designation C168;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
2、 the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This standard provides definitions,symbols,units,andabbreviations of terms used in ASTM standards pertaining tothermal insulating materials,and to materials associated wi
3、ththem.1.2 This terminology is not intended to be used to classifyinsulation materials as having particular properties.Rather,classification of insulation materials is to be done by thematerial standards themselves.1.3 This standard does not purport to address all of thesafety concerns,if any,associ
4、ated with its use.It is theresponsibility 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.1.4 This international standard was developed in accor-dance with internationally recognized principles
5、 on standard-ization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade(TBT)Committee.2.Referenced Documents2.1 ASTM Standards:2D3574 Test Methods for Flexible Cellular
6、MaterialsSlab,Bonded,and Molded Urethane FoamsE456 Terminology Relating to Quality and StatisticsE2282 Guide for Defining the Test Result of a Test Method2.2 ISO Standard:ISO 7345 Thermal InsulationPhysical Quantities andDefinitions33.Terminology3.1 Definitions:absorptance,nthe ratio of the radiant
7、flux absorbed by abody to that incident upon it.absorption,ntransformation of radiant energy to a differentform of energy by interaction with matter.apparent thermal conductivity,a,ka,na thermal conduc-tivity assigned to a material that exhibits thermal transmis-sion by several modes of heat transfe
8、r resulting in propertyvariation with specimen thickness,or surface emittance.Seeconductivity,thermal.DISCUSSIONThermal conductivity and resistivity are normally con-sidered to be intrinsic or specific properties of materials and,as such,should be independent of thickness.When nonconductive modes of
9、heat transfer are present within the specimen(radiation,free convec-tion)this may not be the case.To indicate the possible presence of thisphenomena(for example,thickness effect)the modifier“apparent”isused,as in apparent thermal conductivity.DISCUSSIONTest data using the“apparent”modifier must be q
10、uotedonly for the conditions of the measurement.Values of thermal conduc-tance(material C)and thermal resistance(material R)calculated fromapparent thermal conductivity or resistivity,are valid only for the sameconditions.DISCUSSIONTest data labeled with“apparent”shall not include anyequipment relat
11、ed measurement errors induced due to measurementattempts beyond an apparatus range or calibration.DISCUSSIONUse of the“apparent”modifier with system C or systemR measurements is not permitted.apparent thermal resistivity,ra,na thermal resistivityassigned to a material that exhibits thermal transmiss
12、ion byseveral modes of heat transfer resulting in property variationwith specimen thickness,or surface emittance.Seeresistivity,thermal.DISCUSSIONSee entire discussion under apparent thermal conduc-tivity.area weight,nweight per unit area for a specified sample,inunits of lb/ft2(kg/m2).aerogel,na ho
13、mogeneous,low-density solid phase materialderived from a gel,in which the liquid component of the gelhas been replaced with a gas.DISCUSSIONThe resulting material has a porous structure with anaverage pore size below the mean free path of air molecules at standardatmospheric pressure and temperature
14、.1This terminology is under the jurisdiction of ASTM Committee C16 onThermal Insulation and is the direct responsibility of Subcommittee C16.94 onTerminology.Current edition approved June 1,2017.Published June 2017.Originallyapproved in 1941.Last previous edition approved in 2015 as C168 15a.DOI:101
15、520/C0168-17.2For 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.3Available from American National Standards Institute
16、(ANSI),25 W.43rd St.,4th Floor,New York,NY 10036,http:/www.ansi.org.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 batt,nbl
