ASTM E96 E96M-2010 8125 9725 Standard Test Methods for Water Vapor Transmission of Materials《材料的水蒸气散布的标准试验方法》.pdf

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1、Designation: E96/E96M 10Standard 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 Department of Defense.1. Scope1.1 These test methods cover the determination of watervapor tr

3、ansmission (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 thicknessexcept a

4、s 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 no

5、t 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 equivalen

6、ts; 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 not

7、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 Standards:

8、2C168 Terminology Relating to Thermal InsulationD449 Specification for Asphalt Used in Dampproofing andWaterproofingD2301 Specification for Vinyl Chloride Plastic Pressure-Sensitive Electrical Insulating TapeE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Me

9、thod3. 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 flat material of unit thicknessinduced by unit vapor pressure difference betwee

10、n two specificsurfaces, under specified temperature and humidity conditions.3.1.1 DiscussionPermeability is a property of a material,but the permeability of a body that performs like a materialmay be used. Permeability is the arithmetic product of per-meance and thickness.water vapor permeancethe ti

11、me 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.3.1.2 DiscussionPermeance is a performance evaluationand not a property of a material.3.2 w

12、ater 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 the Desiccant Method the test specimen is sealed tothe open mou

13、th of a test dish containing a desiccant, and the1These test methods are under the jurisdiction of ASTM Committee C16 onThermal Insulation and are the direct responsibility of Subcommittee C16.33 onInsulation Finishes and Moisture.Current edition approved Oct. 1, 2010. Published February 2011. Origi

14、nallyapproved in 1953. Last previous edition approved in 2000 as E96 001. DOI:10.1520/E0096_E0096M-10.2For 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

15、Document Summary page onthe ASTM website.TABLE 1 Metric Units and Conversion FactorsA,BMultiply byTo Obtain (for thesame test condition)WVTg/hm21.43 grains/hft2grains/hft20.697 g/hm2Permeanceg/Pasm21.75 3 1071 Perm (inch-pound)1 Perm (inch-pound) 5.72 3 108g/Pasm2Permeabilityg/Pasm 6.88 3 1081 Perm

16、inch1 Perm inch 1.45 3 109g/PasmAThese units are used in the construction trade. Other units may be used inother standards.BAll conversions of mm Hg to Pa are made at a temperature of 0C.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United State

17、s.assembly placed in a controlled atmosphere. Periodic weigh-ings determine the rate of water vapor movement through thespecimen into the desiccant.4.2 In the Water Method, the dish contains distilled water,and the weighings determine the rate of vapor movementthrough the specimen from the water to

18、the controlled atmo-sphere. The vapor pressure difference is nominally the same inboth 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 transfe

19、rthrough permeable and semipermeable materials, expressed insuitable units. These values 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 sh

20、ould beselected that most closely approach the conditions of use.While any set of conditions 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 o

21、r water vapor. It may be ofany shape. Light weight is desirable. A large, shallow dish 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.2(3000mm2). The desicca

22、nt or water area shall be not less than themouth area except if a grid is used, as provided 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 speci

23、men area is larger than the mouth area,this overlay upon the ledge is a source of error, 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 wate

24、r vapor transmission. The magnitude of the erroris a complex function of the thickness, ledge 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

25、exceed34 in. (19 mm) for a 10-in. (254-mm) orlarger mouth (square or circular) or18 in. (3 mm) for a 5-in.(127-mm) mouth (square or circular). For a 3-in. (76-mm)mouth (square or circular) the ledge should not exceed 0.11 in.(2.8 mm) wide. An allowable ledge may be interpolated forintermediate sizes

26、 or calculated according to Joy and Wil-son.(1) A rim around the ledge (Fig. X2.1) may be useful. If arim 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 th

27、e mouth) is satisfactory for eithermethod.6.2 Test ChamberThe room or cabinet where the as-sembled test dishes are to be placed shall have a controlledtemperature (see Note 1) and relative humidity. Some standardtest conditions that have been useful are given inAppendix X1.The temperature chosen sha

28、ll be determined according to thedesired application of the material to be tested (see AppendixX1). The relative 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 an

29、d relative humidity shallbe measured frequently4or preferably recorded continuously.Air shall be continuously 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 an

30、d 0.3 ms-1). Suitable racksshall be provided on which to place the test dishes within thetest chamber.NOTE 1Simple 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

31、 forthat arrangement. Temperatures of 73.4F (23C) and 80F (26.7C) are inuse and are satisfactory for this purpose. 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 shou

32、ld not be cooler than the water to avoid condensation on the testspecimen.6.3 Balance and WeightsThe balance shall 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

33、during thesteady-state period (Note 2). A light wire sling may besubstituted for the usual pan to accommodate a larger 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 0.000

34、1 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 (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 weight

35、s 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 requirements of this paragraph can be met bycontinuing the steady state for 36 days. An analytical balance that is muchmore sensitive will permit more rapid results on specimen

36、s below 1 perm(57 ngPa-1s-1m-2) when the assembled dish is not excessively heavy.7. Materials7.1 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. 8(2.36-mm) sieve, and free of fines that will pass a No. 30(600-m) sieve, s

37、hall be used (Note 3). It shall be dried at400F (200C) before use.3The 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.E96/E96M 102NOTE 3If CaCl2will react chemically on t

38、he 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 specimen

39、 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 affec

40、t 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 under

41、test. 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 re

42、presentative 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 the

43、 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 tested

44、 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 qu

47、adrant 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 additi

48、onal 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

49、 increases 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 duplicates themouth shape and size and is directly above it. A tem