1、Designation: C870 11Standard Practice forConditioning of Thermal Insulating Materials1This standard is issued under the fixed designation C870; 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
2、parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice covers the conditioning of thermal insu-lating materials for tests. Since prior exposure of insulatingmaterials to high or low humi
3、dity will affect the equilibriummoisture content, a procedure is also given for preconditioningthe materials.1.2 The values stated in either SI units or inch-pound unitsare to be regarded separately as standard. The values stated ineach system may not be exact equivalents; therefore, eachsystem shal
4、l be used independently of the other. Combiningvalues from the two systems may result in non-conformancewith the standard.1.3 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 establish appro-
5、priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2C168 Terminology Relating to Thermal InsulationE41 Terminology Relating To ConditioningE171 Specification for Atmospheres for Conditioning andTesting
6、Flexible Barrier MaterialsE337 Test Method for Measuring Humidity with a Psy-chrometer (the Measurement of Wet- and Dry-Bulb Tem-peratures)2.2 ISO Standard:3ISO 544 Standard Atmospheres for Conditioning and/orTesting3. Terminology3.1 DefinitionsDefinitions of terms in the field of thermalinsulating
7、materials are given in Terminology C168. Thefollowing definitions are derived from Terminology E41:3.1.1 moisture contentthe moisture present in a material,as determined by definite prescribed methods, expressed as apercentage of the mass of the sample on either of the followingbases: (1) original m
8、ass (see 3.1.1); (2) moisture-free weight(see 3.1.2).3.1.1.1 DiscussionThis is variously referred to as mois-ture content, or moisture “as is” or “as received.”3.1.1.2 DiscussionThis is also referred to as moistureregain (frequently contracted to “regain”), or moisture contenton the “oven-dry,” “moi
9、sture-free,” or “dry” basis.3.1.2 moisture equilibriumthe condition reached by asample when the net difference between the amount of mois-ture sorbed and the amount desorbed, as shown by a change inmass, shows no trend and becomes insignificant.3.1.2.1 DiscussionSuperficial equilibrium with the film
10、 ofair in contact with the specimen is reached very rapidly. Stableequilibrium can be reached in a reasonable time only if the airto which the sample is exposed is in motion. Stable equilibriumwith air in motion is considered to be realized when successiveweighings do not show a progressive change i
11、n mass greaterthan the tolerances established for the various insulatingmaterials.3.1.3 moisture regainthe moisture in a material deter-mined under prescribed conditions, and expressed as a percent-age of the mass of the moisture-free specimen.3.1.3.1 DiscussionMoisture regain calculations are com-m
12、only based on the mass of a specimen that has been dried byheating in an oven. If the air in the oven contains moisture, theoven-dried specimen will contain some moisture even when itno longer shows a significant change in mass. In order toensure that the specimen is moisture-free, it must be expose
13、d todesiccated air until it shows no further significant change in itsmass. For drying temperatures above 100C 212F, themoisture content of the oven atmosphere is negligible.3.1.3.2 DiscussionMoisture regain may be calculatedfrom moisture content using Eq 1, and moisture content may becalculated fro
14、m moisture regain using Eq 2 as follows:1This practice is under the jurisdiction of ASTM Committee C16 on ThermalInsulation and is the direct responsibility of Subcommittee C16.31 on Chemical andPhysical Properties.Current edition approved April 1, 2011. Published April 2011. Originallyapproved in 1
15、977. Last previous edition approved in 2004 as C870 96 (2004).DOI: 10.1520/C0870-11.2For 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 p
16、age onthe ASTM website.3Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036, http:/www.ansi.org.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.R 5C100 2 C3 100 (1)C 5R100 1 R3 10
17、0 (2)where:C = moisture content, % (see 3.1.1), andR = moisture regain, % (see 3.1.3).3.2 Definitions of Terms Specific to This StandardThefollowing descriptions apply only to the usage of terms in thispractice:3.2.1 preconditioned moisture equilibriumThe moisturecondition reached by a sample or spe
18、cimen after exposure tomoving air at the standard atmosphere for preconditioning. Thefinal condition may be established after a specified period oftime, or at a moisture equilibrium that is considered to havebeen reached when the change in mass of a specimen insuccessive weighings made at intervals
19、of not less than 2 hdoes not exceed 0.2 % of the mass of the specimen.3.2.2 conditioned moisture equilibriumThe moisture con-dition reached by a sample or specimen during free exposure tomoving air controlled at specified conditions. For test purposes,moisture equilibrium must be reached by absorpti
20、on, startingfrom a relatively low moisture content (see 3.2.3). Moistureequilibrium for testing is considered to have been reachedwhen the rate of increase in the mass of a sample or specimendoes not exceed that specified for the material being tested. Inthe absence of a specified rate, an increase
21、of less than 0.1 %of the sample mass after a 24-h exposure is consideredsatisfactory.3.2.2.1 DiscussionBecause the standard preconditioningatmosphere covers a range of relative humidities, the closeapproach to equilibrium is, in general, warranted only at the topof the range. At lower humidities exp
22、osure for several hours isusually sufficient.3.2.3 standard preconditioning atmosphereAn atmo-sphere having uncontrolled humidity and a constant tempera-ture within the range from 100 to 120C 212 to 248F, or aspecified lower temperature if these temperatures would bedestructive to the specimens. Ref
23、er to material specification.3.2.4 standard conditioning atmosphereAir maintained ata relative humidity of 50 6 5 % and at a temperature of 23 62C 73 6 4F. This atmosphere may be used for testingwithout preconditioning specimens if it has been determinedthat the property being measured is not affect
24、ed by the moisturecontent of the material. Other atmospheric conditions may bespecified for specific materials; such conditions and theirtolerances will be included in pertinent standards. See Speci-fication E171 for other suggested atmospheric conditions.3.2.5 See Appendix X1-Appendix X3 for relate
25、d nonman-datory information.4. Summary of Practice4.1 Specimens are brought to a low moisture content in thepreconditioning atmosphere, and subsequently brought to con-ditioned moisture equilibrium in the conditioning atmospherein accordance with the specified test method.5. Significance and Use5.1
26、The conditioning prescribed in this recommended prac-tice is designed to obtain reproducible test results on thermalinsulating materials. Results of tests obtained on these materi-als under uncontrolled atmospheric conditions are not compa-rable with each other. Some of the physical properties ofthe
27、rmal insulating materials are influenced by relative humidityand temperature in a manner that affects the results of tests. Inthis regard, such information is provided in pertinent materialspecifications and test methods by stating the physical proper-ties relative to the specific ambient or test co
28、nditions.NOTE 1In some cases (for example, dimensionally unstable materi-als), the dry mass cannot easily be established and original mass has to beused.6. Apparatus6.1 Conditioning Room or Chamber:6.1.1 Equipment for maintaining the standard atmospherefor testing insulating materials throughout the
29、 room or chamberwithin the tolerance given in 3.2.4, and including facilities forcirculating the air over the exposed sample or specimen or,alternatively, facilities such as a revolving rack for moving thespecimens in the prevailing atmosphere.6.1.2 Equipment for recording the temperature and relati
30、vehumidity of the air in the conditioning room or chamber.6.2 Instrumentation, for checking the recorded relative hu-midity, as directed on Test Method E337.6.3 Preconditioning Cabinet, Room, or Chamber, equippedwith apparatus for maintaining to standard preconditioningatmosphere throughout, within
31、the tolerance given in 3.2.3.6.4 Balance, having a sensitivity of 1 part in 1000 of themass of the specimen.7. Procedure7.1 Determine the temperature and relative humidity of theair in the conditioning room or chamber (6.1) and, if precon-ditioning is required, in the preconditioning chamber (6.3)in
32、accordance with Test Method E337. If necessary, adjust theconditions within the specified limits before proceeding tocondition the sample or specimen.7.2 If both preconditioning and conditioning are specified inthe test method or in a material specification, proceed asdirected in 7.3, 7.4, and 7.5.
33、If preconditioning is not required,condition the sample or specimen as directed in 7.3 and 7.5.7.3 Expose the specimens or samples in the preconditioningor conditioning atmosphere in such a manner that the movingair will have access freely to all surfaces of the material. Unlessotherwise specified i
34、n the applicable test method or materialspecification, expose specimens after cutting and sizing.7.4 Place the specimen or sample in the standard precondi-tioning atmosphere. Keep the sample or specimen in thisatmosphere until it has attained moisture equilibrium forpreconditioning as defined in 3.2
35、.1.7.5 Place the specimen or sample in the standard condition-ing atmosphere as defined in 3.2.4. Keep the sample orspecimen in this atmosphere until the material has attainedconditioned moisture equilibrium for testing as defined in3.2.2.C870 1128. Keywords8.1 conditioning; preconditioning; thermal
36、 insulatingmaterialsAPPENDIXES(Nonmandatory Information)X1. IMPORTANCE OF TEMPERATUREX1.1 A tolerance of 61C has been adopted in a number ofcountries. It is recommended, along with 62 % relative hu-midity, by Specification E171 and ISO 544 on standard atmo-spheres whenever close tolerances are requi
37、red. Both tempera-ture and relative humidity can have significant effects on thephysical properties of insulating materials. For some propertiesa change of 1C may have nearly as much effect as a change of2 % relative humidity. For organic fibers and foam materials,the temperature effect may be great
38、er than the relative humidityeffect.X2. IMPORTANCE OF PRECONDITIONINGX2.1 The physical properties of a sample at 50 % relativehumidity depend upon whether the sample was brought to50 % from higher or lower relative humidities. This “humidityhysteresis effect” can be 5 to 25 % of the test value for m
39、anyphysical properties. For example, a hysteresis effect of 1.5 %moisture content (or 25 % of the test value of 6 % moisturecontent) is typical. Preconditioning on the dry side with ahumidity range specified would avoid most of the hysteresiseffect and result in the moisture content of a given sampl
40、ebeing established within 0.15 %, when the sample is laterconditioned to 50 % relative humidity and 23C. Conditioningdown to 50 % gives most materials a moisture content verynearly the same as conditioning up to 60 %.X2.2 For the sake of obtaining close interlaboratory agree-ment, especially on phys
41、ical properties, a specified precondi-tioning procedure is necessary, but not always sufficient. Whilepreconditioning practically eliminates the hysteresis effect, ithas little influence on strain relaxation effects. The latterdepends upon the entire previous moisture history of thesample, especiall
42、y on the conditions of initial drying andtension, and on the duration and degree of subsequent excur-sions to high humidities (that is, above about 58 % relativehumidity). Consequently, for very close interlaboratory agree-ment, a standardized procedure for handling the sample frommanufacture to res
43、ting may be required.X2.3 For production control and similar intralaboratorypurposes, the preconditioning step often may be eliminated.For some properties and materials preconditioning may not benecessary, either because of the smallness of the humidityhysteresis effect or because of lower test accu
44、racyrequirements.X3. IMPORTANCE OF ACCURATE RELATIVE HUMIDITY CONDITIONINGX3.1 It is essential that the relative humidity be determinedwith accuracy and that it be rechecked frequently. The proce-dure of Test Method E337 should be followed closely.ASTM International takes no position respecting the
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46、subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Head
47、quarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This sta
48、ndard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org). Permission rights to photocopy the standard may also be secured from the ASTM website (www.astm.org/COPYRIGHT/).C870 113
