1、Designation:D307994(Reapproved 2009)1Standard Test Method forWater Vapor Transmission of Flexible Heat-Sealed Packagesfor Dry Products1This standard is issued under the fixed designation D3079;the number immediately following the designation indicates the year oforiginal adoption or,in the case of r
2、evision,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.1NOTEUnits information was revised editorially in May 2009.1.Scope1.1 This test method covers the determination of
3、 the amountof water vapor transmission for flexible heat-sealed packagesunder specified conditions of exposure.NOTE1Adequate heat-seal efficiency should be determined prior tothis test method.1.2 The values stated in SI units are to be regarded asstandard.No other units of measurement are included i
4、n thisstandard.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-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2.R
5、eferenced Documents2.1 ASTM Standards:2E691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3.Terminology3.1 Definitions:3.1.1 water vapor transmission of a desiccant-filledpackagethe increase in mass after exposure to a specifiedhumid environment(90 6 2%re
6、lative humidity,37.8 61.1C).The mass increase may be divided by a time unit togive a rate(for example,grams per 30 days).It is assumed thatthis mass increase is due to water vapor transmission(throughthe package)from the test environment to the desiccant.4.Summary of Test Method4.1 Test samples are
7、filled with desiccant and after sealingare exposed to 37.8 6 1.1C and 90 6 2%relative humidityfor at least 1 month.Measurements of mass are taken atintervals to determine the average rate of mass change.Controls are used to monitor mass gain of package materials.5.Significance and Use5.1 This test m
8、ethod determines the water vapor barrierproperties of the package.With proper precautions and back-ground experience,reproducible results can be obtained to aidin the selection of proper package materials required to providethe product shelf-life desired.This test method may be used toestablish a pe
9、rformance specification.6.Apparatus6.1 Weighing BalanceAnalytical balance accurate to 1mg.6.2 Test ChamberA test room or cabinet provided withconditioned air that is continuously circulated around thespecimens under test.The conditions in the chamber shall besuch that no condensation occurs on the s
10、pecimens.7.Materials7.1 DesiccantAnhydrous calcium chloride in the form ofsmall lumps is recommended for this test method.This shouldpass a No.8(2.36-mm)sieve,and be free of fines that will passa No.30(600-m)sieve.The desiccant should be dried for atleast 24 h at 200C prior to use.8.Test Specimens8.
11、1 Test specimens shall be representative of the packagesbeing tested,and shall be closed and sealed in the normalmanner.8.2 Review the precision and bias statement to determinethe number of samples required to meet requirements.Gener-ally,three to five samples have been found to be sufficient formos
12、t applications.8.3 Each test specimen should be half full of desiccant up to100 g of desiccant.If the half-full capacity is greater than 1001This test method is under the jurisdiction ofASTM Committee F02 on FlexibleBarrier Packaging and is the direct responsibility of Subcommittee F02.10 onPermeati
13、on.Current edition approved May 1,2009.Published June 2009.Originallyapproved in 1972.Last previous edition approved in 2003 as D3079 94(2003).DOI:10.1520/D3079-94R09E01.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual B
14、ook 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 States1 g of desiccant,the package shall be less than half full,but eachshall contain approxim
15、ately the same quantity of desiccant.8.4 If more than one type of package is tested for compari-son purposes,all types should have the same(as close aspossible)surface area and shape,and should contain the samequantity of desiccant.8.5 An appropriate number of identical control packagesshall be prep
16、ared,containing no desiccant.9.Procedure9.1 Place the selected quantity of the desiccant inside thetest specimen with no other contents,but with a suitable liner,if the package normally requires a liner,so that the package canbe handled with the regular automatic packaging machinery.Close and seal the specimens and controls in exactly the samemanner that packages with normal contents are closed andsealed.This test method may be applied to hand-sealedpackages,but take great care to ensure a compl
