ASTM E96 E96M-2014 8930 Standard Test Methods for Water Vapor Transmission of Materials《材料的水蒸气渗透性的标准试验方法》.pdf

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1、Designation: E96/E96M 14Standard Test Methods forWater Vapor Transmission of Materials1This standard is issued under the fixed designation E96/E96M; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A numbe

2、r in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the U.S. Department of Defense.1. Scope1.1 These test methods cover the determination of watervap

3、or transmission (WVT) of materials through which thepassage of water vapor may be of importance, such as paper,plastic films, other sheet materials, fiberboards, gypsum andplaster products, wood products, and plastics. The test methodsare limited to specimens not over 114 in. 32 mm in thicknessexcep

4、t as provided in Section 9. Two basic methods, theDesiccant Method and the Water Method, are provided for themeasurement of permeance, and two variations include serviceconditions with one side wetted and service conditions withlow humidity on one side and high humidity on the other.Agreement should

5、 not be expected between results obtained bydifferent methods. The method should be selected that morenearly approaches the conditions of use.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 equiva

6、lents; therefore, eachsystem shall be used independently of the other. Combiningvalues from the two systems may result in non-conformancewith the standard. However, derived results can be convertedfrom one system to the other using appropriate conversionfactors (see Table 1).1.3 This standard does n

7、ot purport to address all of thesafety problems, 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. Referenced Documents2.1 ASTM Standar

8、ds:2C168 Terminology Relating to Thermal InsulationE177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsD449 Specification for Asphalt Used in Dampproofing andWaterproofingD2301 Specification for Vinyl Chloride Plastic Pressure-Sensitive Electrical Insulating TapeE691 Practice fo

9、r Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3. Terminology3.1 Definitions of terms used in this standard will be foundin Terminology C168, from which the following is quoted:“water vapor permeabilitythe time rate of water vaportransmission through unit area of fla

10、t material of unit thicknessinduced by unit vapor pressure difference between two specificsurfaces, under specified temperature and humidity conditions.DiscussionPermeability is a property of a material, but thepermeability of a body that performs like a material may beused. Permeability is the arit

11、hmetic product of permeance andthickness.water vapor permeancethe time rate of water vaportransmission through unit area of flat material or constructioninduced by unit vapor pressure difference between two specificsurfaces, under specified temperature and humidity conditions.DiscussionPermeance is

12、a performance evaluation and nota property of a material.3.2 water vapor transmission ratethe steady water vaporflow in unit time through unit area of a body, normal to specificparallel surfaces, under specific conditions of temperature andhumidity at each surface.”4. Summary of Test Methods4.1 In t

13、he Desiccant Method the test specimen is sealed tothe open mouth of a test dish containing a desiccant, and theassembly placed in a controlled atmosphere. Periodic weigh-ings determine the rate of water vapor movement through thespecimen into the desiccant.1These test methods are under the jurisdict

14、ion of ASTM Committee C16 onThermal Insulation and are the direct responsibility of Subcommittee C16.33 onInsulation Finishes and Moisture.Current edition approved Oct. 15, 2014. Published January 2015. Originallyapproved in 1953. Last previous edition approved in 2013 as E96 13. DOI:10.1520/E0096_E

15、0096M-14.2For 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 onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive,

16、 PO Box C700, West Conshohocken, PA 19428-2959. United States14.2 In the Water Method, the dish contains distilled water,and the weighings determine the rate of vapor movementthrough the specimen from the water to the controlled atmo-sphere. The vapor pressure difference is nominally the same inboth

17、 methods except in the variation, with extremes of humid-ity on opposite sides.5. Significance and Use5.1 The purpose of these tests is to obtain, by means ofsimple apparatus, reliable values of water vapor transferthrough permeable and semipermeable materials, expressed insuitable units. These valu

18、es are for use in design, manufacture,and marketing. A permeance value obtained under one set oftest conditions may not indicate the value under a different setof conditions. For this reason, the test conditions should beselected that most closely approach the conditions of use.While any set of cond

19、itions may be used and those conditionsreported, standard conditions that have been useful are shownin Appendix X1.6. Apparatus6.1 Test DishThe test dish shall be of any noncorrodingmaterial, impermeable to water or water vapor. It may be ofany shape. Light weight is desirable. A large, shallow dish

20、 ispreferred, but its size and weight are limited when an analyticalbalance is chosen to detect small weight changes.The mouth ofthe dish shall be as large as practical and at least 4.65 in.23000mm2. The desiccant or water area shall be not less than themouth area except if a grid is used, as provid

21、ed in 12.1, itseffective area shall not exceed 10 % of the mouth area. Anexternal flange or ledge around the mouth, to which thespecimen may be attached, is useful when shrinking or warpingoccurs. When the specimen area is larger than the mouth area,this overlay upon the ledge is a source of error,

22、particularly forthick specimens. This overlay material should be masked asdescribed in 10.1 so that the mouth area defines the test area.The overlay material results in a positive error, indicatingexcessive water vapor transmission.The magnitude of the erroris a complex function of the thickness, le

23、dge width, moutharea, and possibly the permeability. This error is discussed byJoy and Wilson (1)3(see 13.4.3). This type of error should belimited to about 10 to 12 %. For a thick specimen the ledgeshould not exceed34 in. 19 mm for a 10-in. 254-mm orlarger mouth (square or circular) or18 in. 3 mm f

24、or a 5-in.127-mm mouth (square or circular). For a 3-in. 76-mmmouth (square or circular) the ledge should not exceed 0.11 in.2.8 mm wide. An allowable ledge may be interpolated forintermediate sizes or calculated according to Joy and Wil-son.(1) A rim around the ledge (Fig. X2.1) may be useful. If a

25、rim is provided, it shall be not more than14 in. 6 mm higherthan the specimen as attached. Different depths may be usedfor the Desiccant Method and Water Method, but a34-in.19-mm depth (below the mouth) is satisfactory for eithermethod.6.2 Test ChamberThe room or cabinet where the as-sembled test di

26、shes are to be placed shall have a controlledtemperature (see Note 1) and relative humidity. Some standardtest conditions that have been useful are given in Appendix X1.The temperature chosen shall be determined according to thedesired application of the material to be tested (see AppendixX1). The r

27、elative humidity shall be maintained at 50 6 2%,except where extremes of humidities are desired, when theconditions shall be 100 6 1.8F 38 6 1C and 90 6 2%relative humidity. Both temperature and relative humidity shallbe measured frequently4or preferably recorded continuously.Air shall be continuous

28、ly circulated throughout the chamber,with a velocity sufficient to maintain uniform conditions at alltest locations. The air velocity over the specimen shall bebetween 0.066 and 1 ft/s 0.02 and 0.3 ms-1. Suitable racksshall be provided on which to place the test dishes within thetest chamber.NOTE 1S

29、imple temperature control by heating alone is usually madepossible at 90F 32C. However, it is very desirable to enter thecontrolled space, and a comfortable temperature is more satisfactory forthat arrangement. Temperatures of 73.4F 23C and 80F 26.7C are inuse and are satisfactory for this purpose.

30、With cyclic control, the averagetest temperature may be obtained from a sensitive thermometer in a massof dry sand. The temperature of the chamber walls facing a specimen overwater should not be cooler than the water to avoid condensation on the testspecimen.6.3 Balance and WeightsThe balance shall

31、be sensitive toa change smaller than 1 % of the weight change during theperiod when a steady state is considered to exist. The weightsused shall be accurate to 1 % of the weight change during thesteady-state period (Note 2). A light wire sling may besubstituted for the usual pan to accommodate a lar

32、ger andheavier load.6.4 Thickness-Measuring GageThe nominal thickness ofthe specimen shall be determined using a thickness-measuringgage with an accuracy of 61 % of the reading or 0.0001 in.0.0025 mm, whichever is greater.NOTE 2For example: 1-perm 57 ngPa-1s-1m-2 specimen 10 in.254 mm square at 80F

33、26.7C passes 8.6 grains or 0.56 g/day. In 18days of steady state, the transfer is 10 g. For this usage, the balance musthave a sensitivity of 1 % of 10 g or 0.1 g and the weights must be accurateto 0.1 g. If, however, the balance has a sensitivity of 0.2 g or the weightsare no better than 0.2 g, the

34、 requirements of this paragraph can be met by3The boldface numbers in parentheses refer to the list of references at the end ofthis standard.4The minimum acceptable is to perform this measurement each time the sampleis weighed.TABLE 1 Metric Units and Conversion FactorsA,BMultiply byTo Obtain (for t

35、hesame test condition)WVTg/hm21.43 grains/hft2grains/hft20.697 g/hm2Permeanceg/Pasm21.75 1071 Perm (inch-pound)1 Perm (inch-pound) 5.72 108g/Pasm2Permeabilityg/Pasm 6.88 1081 Perm inch1 Perm inch 1.45 109g/PasmAThese units are used in the construction trade. Other units may be used in otherstandards

36、.BAll conversions of mm Hg to Pa are made at a temperature of 0C.E96/E96M 142continuing the steady state for 36 days.An analytical balance that is muchmore sensitive will permit more rapid results on specimens below 1 perm57 ngPa-1s-1m-2 when the assembled dish is not excessively heavy.7. Materials7

37、.1 Desiccant and Water:7.1.1 For the Desiccant Method, anhydrous calcium chlo-ride in the form of small lumps that will pass a No. 82.36-mm sieve, and free of fines that will pass a No. 30600-m sieve, shall be used (Note 3). It shall be dried at400F 200C before use.NOTE 3If CaCl2will react chemicall

38、y on the specimen, an adsorbingdesiccant such as silica gel, activated at 400F 200C, may be used; butthe moisture gain by this desiccant during the test must be limited to 4 %.7.1.2 For the Water Method, distilled water shall be used inthe test dish.7.2 SealantThe sealant used for attaching the spec

39、imen tothe dish, in order to be suitable for this purpose, must be highlyresistant to the passage of water vapor (and water). It must notlose weight to, or gain weight from, the atmosphere in anamount, over the required period of time, that would affect thetest result by more than 2 %. It must not a

40、ffect the vaporpressure in a water-filled dish. Molten asphalt or wax isrequired for permeance tests below 4 perms 230 ngm-2s-1Pa-1. Sealing methods are discussed in Appendix X2.8. Sampling8.1 The material shall be sampled in accordance withstandard methods of sampling applicable to the material und

41、ertest. The sample shall be of uniform thickness. If the materialis of nonsymmetrical construction, the two faces shall bedesignated by distinguishing marks (for example, on a one-side-coated sample, “I” for the coated side and “II” for theuncoated side).9. Test Specimens9.1 Test specimens shall be

42、representative of the materialtested. When a product is designed for use in only one position,three specimens shall be tested by the same method with thevapor flow in the designated direction. When the sides of aproduct are indistinguishable, three specimens shall be testedby the same method. When t

43、he sides of a product are differentand either side may face the vapor source, four specimens shallbe tested by the same method, two being tested with the vaporflow in each direction and so reported.9.2 A slab, produced and used as a laminate (such as afoamed plastic with natural “skins”) may be test

44、ed in thethickness of use. Alternatively, it may be sliced into two ormore sheets, each being separately tested and so reported asprovided in 9.4, provided also, that the “overlay upon the cupledge” (6.1) of any laminate shall not exceed18 in. 3 mm.9.3 When the material as used has a pitted or textu

45、redsurface, the tested thickness shall be that of use. When it ishomogeneous, however, a thinner slice of the slab may betested as provided in 9.4.9.4 In either case (9.2 or 9.3), the tested overall thickness, ifless than that of use, shall be at least five times the sum of themaximum pit depths in

46、both its faces, and its tested permeanceshall be not greater than 5 perms 300 ngm-2s-1Pa-1.9.5 For homogeneous (not laminated) materials with thick-ness greater than12 in., the overall nominal thickness of eachspecimen shall be measured with an accuracy of 61%ofthereading at the center of each quadr

47、ant and the results averaged.9.6 When testing any material with a permeance less than0.05 perms 3 ngm-2s-1Pa-1 or when testing a low permeancematerial that may be expected to lose or gain weight through-out the test (because of evaporation or oxidation), it is stronglyrecommended that an additional

48、specimen, or “dummy,” betested exactly like the others, except that no desiccant or wateris put in the dish. Failure to use this dummy specimen toestablish modified dish weights may significantly increase thetime required to complete the test. Because time to reachequilibrium of water permeance incr

49、eases as the square ofthickness, thick, particularly hygroscopic, materials may takeas long as 60 days to reach equilibrium conditions.10. Attachment of Specimen to Test Dish10.1 Attach the specimen to the dish by sealing (andclamping if desired) in such a manner that the dish mouthdefines the area of the specimen exposed to the vapor pressurein the dish. If necessary, mask the specimen top surface,exposed to conditioned air so that its exposure duplicat