1、Designation:D743820Standard Practice forField Calibration and Application of Hand-Held MoistureMeters1This standard is issued under the fixed designation D7438;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision
2、.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 practice applies to the measurement of moisturecontent of solid wood,including solid wood products contain-ing additives,that is,ch
3、emicals or adhesives,by hand-heldmoisture meters under conditions of end-use.1.1.1 This practice includes calibration,use,and interpreta-tion of meters for conditions that relate to wood productcharacteristics,such as nonuniform grain and growth ringorientation,and to end-use process conditions,such
4、 as mois-ture gradients.1.1.2 Meters employing differing technologies will not nec-essarily provide equivalent readings under the same conditions.When this practice has been applied,it is assumed that thereferenced meter is acceptable unless otherwise specified.Meters shall have been calibrated by T
5、est Methods D4444.1.2 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard1.3 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 e
6、stablish appro-priate safety,health,and environmental practices and deter-mine the applicability of regulatory limitations prior to use.1.4 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principle
7、s 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:2D9 Terminology Relating to Wood and Wood-Based Prod-uctsD2915 Practice for Sampling and Data-Analysis
8、for Struc-tural Wood and Wood-Based ProductsD4442 Test Methods for Direct Moisture Content Measure-ment of Wood and Wood-Based MaterialsD4444 Test Method for Laboratory Standardization andCalibration of Hand-Held Moisture MetersD4933 Guide for Moisture Conditioning of Wood andWood-Based MaterialsD67
9、82 Test Methods for Standardization and Calibration ofIn-Line Dry Lumber Moisture Meters2.2 Other ASTM Sources:ASTM Standards on Precision and Bias for VariousApplications,19923.Terminology3.1 Definitions:3.1.1 For definitions of general terms used in this standardrelated to wood and wood-based prod
10、ucts,refer to Terminol-ogy D9.3.2 Definitions of Terms Specific to This Standard:3.2.1 conductance metersmoisture meters that measurepredominantly ionic conductance between points of appliedvoltage,usually direct current.3.2.1.1 DiscussionDirect-current conductance metershave been commonly referred
11、to as“resistance-type”meters.Most commercial conductance meters are high-input imped-ance(about 1012),wide-range(104to 1012)ohmmeters.Their scales are calibrated to read directly in moisture content(oven-dry mass basis)for a particular calibration species and ata specific reference temperature.3.2.2
12、 capacitive-admittance metersmoisture meters thattransmit electromagnetic wave energy into the wood to detectthe influence of moisture in the wood on these waves as anestimate of moisture content.3.2.2.1 DiscussionWave energy is most often in the radiofrequency range;hand-held meters commonly are pl
13、aceddirectly on the wood surface.4.Significance and Use4.1 Hand-held meters provide a rapid means of samplingmoisture content of wood-based materials during and after1This practice is under the jurisdiction of ASTM Committee D07 on Wood andis the direct responsibility of Subcommittee D07.01 on Funda
14、mental Test Methodsand Properties.Current edition approved Oct.15,2020.Published November 2020.Originallyapproved in 2008.Last previous edition approved in 2013 as D7438 13.DOI:10.1520/D7438-20.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serv
15、iceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United StatesThis international standard was developed in accordance with int
16、ernationally 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.1processing to maintain quality assurance and compliance withstandards.However,these measurements are inferential;thatis,electrical parameters are measured and compared against acalibration to obtain an indirect measure of moisture content.The electr
