1、Designation:D493316(Reapproved 2021)Standard Guide forMoisture Conditioning of Wood and Wood-Based Materials1This standard is issued under the fixed designation D4933;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last r
2、evision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This guide covers standard procedures for conditioningand equilibrating wood and wood-based materials to constantmoisture content
3、.The procedures apply to solid wood,wood-based fiber and particulate materials and panels,and woodproducts containing adhesives.They are intended for use inresearch and development activities,testing laboratories,qual-ity control,and for all other classes of producers and users.This guide includes b
4、ackground material on the importance ofmoisture content control,important definitions and technicaldata,possible types of apparatus,procedures,and the impor-tance of conditioning time.Users should recognize that thenecessary degree of precision and bias varies with the inten-tions of the users.Some
5、research and testing,for example,might require very close control of moisture content,whereascontrol in an industrial storage facility might not require suchclose control.This guide offers procedures that include thesedifferent requirements.1.2 The values stated in SI units are to be regarded asstan
6、dard.The values of temperature in degrees Fahrenheitgiven in Table X1.2 are mathematical conversions that areprovided for information only and are not considered standard.1.3 The following safety hazards caveat pertains only to theprocedure section,Section 6,of this guide.This standard doesnot purpo
7、rt to address all of the safety concerns,if any,associated with its use.It is the responsibility of the user of thisstandard to establish appropriate safety,health,and environ-mental practices and determine the applicability of regulatorylimitations prior to use.1.4 This international standard was d
8、eveloped in accor-dance with internationally recognized principles 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 Docu
9、ments2.1 ASTM Standards:2D9 Terminology Relating to Wood and Wood-Based Prod-uctsD4442 Test Methods for Direct Moisture Content Measure-ment of Wood and Wood-Based MaterialsE104 Practice for Maintaining Constant Relative Humidityby Means of Aqueous Solutions2.2 ISO Standard:ISO 554 Atmospheres for C
10、onditioning and/or TestingSpecifications33.Terminology3.1 Definitions:3.1.1 The following terms are defined in accordance withTerminology D9.3.1.2 equilibrium moisture content,nmoisture content atwhich wood neither gains nor loses moisture to the surroundingair.3.1.2.1 DiscussionEquilibrium moisture
11、 content(EMC)generally connotes a moisture content at which a nominalspecies of solid wood will equilibrate.“Nominal”is used in thesense of a“hypothetical average”rather than an actual species.At constant EMC environmental conditions,however,variouswood-base materials can reach different levels of E
12、MC.It ismore appropriate,therefore,to refer to conditioning at speci-fied relative humidity(RH)and temperature conditions than toa particular EMC.Recommendations for conditioning aregiven in ISO 554.Nominal values for equilibrium moisturecontent(EMC)are given in Appendix X1.Caution must beused in ca
13、lculating or using these values since they represent a1This guide is under the jurisdiction of ASTM Committee D07 on Wood and isthe direct responsibility of Subcommittee D07.01 on Fundamental Test Methods andProperties.Current edition approved Oct.15,2021.Published November 2021.Originallyapproved i
14、n 1989.Last previous edition approved in 2016 as D4933 16.DOI:10.1520/D4933-16R21.2For 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 ont
15、he ASTM website.3Available from American National Standards Institute(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
16、 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?compromise between variation with species,and adsorptionand desorption.Also,wood containing high levels of extrac-tives or chemicals may equilibrate at different moisture con-tents.The data in Tables X1.1 and X1.2 were generated fromthe re