1、=ICAN NATIO ANSI/ASTM D 1276 68(Reapproved 1978)STANDARD-Standard Test Method for WATER VAPOR TRANSMISSION OF SHIPPING CONTAINERS BY CYCLE METHOD 1 T his St ndard is issued under I he fio:d dc,ignation()1276;the numher immediately flllln,.ing the dc.ignatinn indicates the car uf original adupliun It
2、,iq the.:nf revision,the:)car nf last rcvsion.A numhcr in parentheses indicates the year uf last rcapprm al.I.Scope 1.1 This method covers two procedures for determining the water vapor transmission of!hipping containers.a follow 1.1.1 Procedure A.for Reclosahlc Contain-ers,and 1.1.2 Procedure B.for
3、 Containers Not De-signed for Rcclosing.1.2 The test may be applied to the container as packed,or arter one ur more performance tests such as drum,vibration,drop,or actual shipping tests.as required.I.3 For!mall shipping containers requiring greater accuracy in weighing,the water vapor permeability
4、may be determined in accordance with ASTM Method D 1251.Test for Water Vapor Permeability of Packages by Cycle Method.2 2.Significance 2.I This method is normally used to deter-mine the following:2.1.1 Evaluate materials tnd constructions for a specific type of container,2.1.2 Compare performance of
5、 different types of containers,2.I.3 Determine adequacy of protection for a specific product or application,and 2.1.4 Maintain quality control.3.Definitions 3,I cycle-one series of test atmospheres to which the test specimens arc exposed.Nor-mally one cycle will consist of I week of exposure to a te
6、mperature ofO:1:5 F(-17.!2.!C)to be followed by 3 weeks of exposure at a temperature of 100 2 F(37.!:t:1.1 C)and a relative humidity of 90:t:2%.3.2 water-vapor transmission of a con-tainel-for this test.the amount of water transmitted into the container from the test atmosphere during one cycle whil
7、e u desiccant is sealed within.PROCEDURE A-FOR RE(LOSABU.:CONTAIN US 4.Apparatus 4.I Weighing Balance-A weighing balance accurate to within I i When the required amount of desic.:ant is grcttcr than can be weighed on a balance of thb cnsitivity,two or more receptacles shall be ued and weighed indivi
8、dually.When product tests are made,a regular laboratory hal.mcc and drying oven or other appropriate equipment arc required fur making standard moisture determinations pe-culiar to the product.4.2 Receptacle for Desiccant-A non-mois-ture absorptive receptable*to I in.(19 to 38 mm)deep shall be used
9、for holding the desic-cant within the container being tested.It should be equipped with a cover that will rest on the top rim of the receptacle tu protect the desiccant from picking up moisture while being weighed.The size of the weighing receptacle or receptacles shall he such that the exposed areu
10、 of desiccant is nut less than 10%of the area of 1 This mclhud i under the juri.d1 ctiun nf ASTM-63 T.AIIIIUIII Book of.ASTM St1111d11rds,Part 20.370,NOTICE:This standard has either been superseded and replaced by a new version or discontinued.Contact ASTM International(www.astm.org)for the latest i
11、nformation.the test specimen.For testing large containers,this may require u:.ing two or more weighing receptacles.The weighing rcceptade or recep-tacle!.shall be located centrally within the test specimen,using a non-absorptie support when required.4.3 Te.t Chamber-A test room or cabinet provided w
12、ith temperature and humid1ty con-trols that will allow conditioned air to circulate continuously around the specimens under test.The conditions in the chambt:r must be such that no condensation occur on the specimens except during that portion of the cycle when the exposun:is changed from a low temp
13、era-ture to a high humid temperature.5.Desiccant 5.1 A desiccant shall he used that has a high affinity fur water vapor and a high drying efficiency,that is,giving a low water vapor pressure after absorbing a large amount of water.When the test is made to determine the suito.bility of a specific pac
14、kage for a particular produ:t,that prudu:t may be used inside the test specimen instead of the desiccant.in which case the specimen shall he filled to normal capacity.Not E 1-A suitable desicc;mt i5 anhydrous cal-cium chloride in the form of small lumps that will pass a No.8(2.36-mm)sieve.and free o
15、f lines that will pass a No.30(600-11m)sieve.5.2 The quantity of desic:ant shall he suffi-cient to cover uniformly the area of the re:eptacle to a depth of not less than-1 in.(13 mm).The desiccant may require one or more replacements if it becomes noticeably moist during the test.6.Test Specimens 6.
16、1 Test spcdmcns shall he n:presentative of the containers being tested,and shall be dosed and scaled in the normal manner.6.2 Performance shall be based on tests of not less than two representative spe:imens of a given size and type of container.7.Procedure 7.1 When the test is conducted to deter-mine the water vapor transmission of the shipping container for research,development,manufacturing control,specification a:ceptan:e,etc.,use a desiccant as the water absorb-371 D 1276 ing medium.7.2 Whe