1、Designation: E96/E96M 14E96/E96M 15Standard 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 revisi
2、on. A number 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
3、of water vapor transmission (WVT) of materials through which the passage ofwater vapor may be of importance, such as paper, plastic films, other sheet materials, fiberboards, gypsum and plaster products,wood products, and plastics. The test methods are limited to specimens not over 114 in. 32 mm in
4、thickness except as providedin Section 9. Two basic methods, the Desiccant Method and the Water Method, are provided for the measurement of permeance,and two variations include service conditions with one side wetted and service conditions with low humidity on one side and highhumidity on the other.
5、 Agreement should not be expected between results obtained by different methods. The method should beselected that more nearly approaches the conditions of use.1.2 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in eachsystem may
6、not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from thetwo systems may result in non-conformance with the standard. However, derived results can be converted from one system to theother using appropriate conversion factors (see Table 1).1.
7、3 This standard does not purport to address all of the safety problems, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Docum
8、ents2.1 ASTM Standards:2C168 Terminology Relating to Thermal InsulationE177 Practice for Use of the Terms Precision and Bias in ASTM Test MethodsD449D449/D449M Specification for Asphalt Used in Dampproofing and WaterproofingD2301 Specification for Vinyl Chloride Plastic Pressure-Sensitive Electrical
9、 Insulating Tape1 These test methods are under the jurisdiction of ASTM Committee C16 on Thermal Insulation and are the direct responsibility of Subcommittee C16.33 on InsulationFinishes and Moisture.Current edition approved Oct. 15, 2014May 1, 2015. Published January 2015September 2015. Originally
10、approved in 1953. Last previous edition approved in 20132014as E96 13. 14. DOI: 10.1520/E0096_E0096M-14.10.1520/E0096_E0096M-15.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information
11、, refer to the standards Document Summary page on the ASTM website.TABLE 1 Metric Units and Conversion FactorsA,BMultiply by To Obtain (for thesame test condition)WVTg/hm2 1.43 grains/hft2grains/hft2 0.697 g/hm2Permeanceg/Pasm2 1.75 107 1 Perm (inch-pound)1 Perm (inch-pound) 5.72 108 g/Pasm2Permeabi
12、lityg/Pasm 6.88 108 1 Perm inch1 Perm inch 1.45 109 g/PasmA These units are used in the construction trade. Other units may be used in otherstandards.B All conversions of mm Hg to Pa are made at a temperature of 0C.This document is not an ASTM standard and is intended only to provide the user of an
13、ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as publish
14、ed by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method3. Terminology3.1 Definitions of ter
15、ms used in this standard will be found in Terminology C168, from which the following is quoted:“water vapor permeabilitythe time rate of water vapor transmission through unit area of flat material of unit thickness inducedby unit vapor pressure difference between two specific surfaces, under specifi
16、ed temperature and humidity conditions.DiscussionPermeability is a property of a material, but the permeability of a body that performs like a material may be used.Permeability is the arithmetic product of permeance and thickness.water vapor permeancethe time rate of water vapor transmission through
17、 unit area of flat material or construction induced byunit vapor pressure difference between two specific surfaces, under specified temperature and humidity conditions.DiscussionPermeance is a performance evaluation and not a property of a material.3.2 water vapor transmission ratethe steady water v
18、apor flow in unit time through unit area of a body, normal to specificparallel surfaces, under specific conditions of temperature and humidity at each surface.”4. Summary of Test Methods4.1 In the Desiccant Method the test specimen is sealed to the open mouth of a test dish containing a desiccant, a
19、nd the assemblyplaced in a controlled atmosphere. Periodic weighings determine the rate of water vapor movement through the specimen into thedesiccant.4.2 In the Water Method, the dish contains distilled water, and the weighings determine the rate of vapor movement throughthe specimen from the water
20、 to the controlled atmosphere. The vapor pressure difference is nominally the same in both methodsexcept in the variation, with extremes of humidity on opposite sides.5. Significance and Use5.1 The purpose of these tests is to obtain, by means of simple apparatus, reliable values of water vapor tran
21、sfer throughpermeable and semipermeable materials, expressed in suitable units. These values are for use in design, manufacture, andmarketing. A permeance value obtained under one set of test conditions may not indicate the value under a different set ofconditions. For this reason, the test conditio
22、ns should be selected that most closely approach the conditions of use. While any setof conditions may be used and those conditions reported, standard conditions that have been useful are shown in Appendix X1.6. Apparatus6.1 Test DishThe test dish shall be of any noncorroding material, impermeable t
23、o water or water vapor. It may be of any shape.Light weight is desirable.Alarge, shallow dish is preferred, but its size and weight are limited when an analytical balance is chosento detect small weight changes. The mouth of the dish shall be as large as practical and at least 4.65 in.2 3000 mm2. Th
24、e desiccantor water area shall be not less than the mouth area except if a grid is used, as provided in 12.1, its effective area shall not exceed10 % of the mouth area. An external flange or ledge around the mouth, to which the specimen may be attached, is useful whenshrinking or warping occurs. Whe
25、n the specimen area is larger than the mouth area, this overlay upon the ledge is a source of error,particularly for thick specimens. This overlay material should be masked as described in 10.1 so that the mouth area defines thetest area. The overlay material results in a positive error, indicating
26、excessive water vapor transmission. The magnitude of the erroris a complex function of the thickness, ledge width, mouth area, and possibly the permeability. This error is discussed by Joy andWilson (1)3 (see 13.4.3). This type of error should be limited to about 10 to 12 %. For a thick specimen the
27、 ledge should not exceed34 in. 19 mm for a 10-in. 254-mm or larger mouth (square or circular) or 18 in. 3 mm for a 5-in. 127-mm mouth (squareor 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 ledgemay be interpolated for intermedi
28、ate sizes or calculated according to Joy and Wilson.(1) A rim around the ledge (Fig. X2.1) maybe useful. If a rim is provided, it shall be not more than 14 in. 6 mm higher than the specimen as attached. Different depths maybe used for the Desiccant Method and Water Method, but a 34-in. 19-mm depth (
29、below the mouth) is satisfactory for eithermethod.6.2 Test ChamberThe room or cabinet where the assembled test dishes are to be placed shall have a controlled temperature(see Note 1) and relative humidity. Some standard test conditions that have been useful are given in Appendix X1. The temperaturec
30、hosen shall be determined according to the desired application of the material to be tested (see Appendix X1). The relativehumidity shall be maintained at 50 6 2 %, except where extremes of humidities are desired, when the conditions shall be 100 61.8F 38 6 1C and 90 6 2 % relative humidity. Both te
31、mperature and relative humidity shall be measured frequently4 orpreferably recorded continuously. Air shall be continuously circulated throughout the chamber, with a velocity sufficient tomaintain uniform conditions at all test locations. The air velocity over the specimen shall be between 0.066 and
32、 1 ft/s 0.02 and0.3 ms-1. Suitable racks shall be provided on which to place the test dishes within the test chamber.3 The boldface numbers in parentheses refer to the list of references at the end of this standard.4 The minimum acceptable is to perform this measurement each time the sample is weigh
33、ed.E96/E96M 152NOTE 1Simple temperature control by heating alone is usually made possible at 90F 32C. However, it is very desirable to enter the controlledspace, and a comfortable temperature is more satisfactory for that arrangement. Temperatures of 73.4F 23C and 80F 26.7C are in use and aresatisfa
34、ctory for this purpose. With cyclic control, the average test temperature may be obtained from a sensitive thermometer in a mass of dry sand. Thetemperature of the chamber walls facing a specimen over water should not be cooler than the water to avoid condensation on the test specimen.6.3 Balance an
35、d WeightsThe balance shall be sensitive to a change smaller than 1 % of the weight change during the periodwhen a steady state is considered to exist. The weights used shall be accurate to 1 % of the weight change during the steady-stateperiod (Note 2). A light wire sling may be substituted for the
36、usual pan to accommodate a larger and heavier load.6.4 Thickness-Measuring GageThe nominal thickness of the specimen shall be determined using a thickness-measuring gagewith 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 spe
37、cimen 10 in. 254 mm square at 80F 26.7C passes 8.6 grains or 0.56 g/day. In 18 days ofsteady state, the transfer is 10 g. For this usage, the balance must have a sensitivity of 1 % of 10 g or 0.1 g and the weights must be accurate to 0.1 g.If, however, the balance has a sensitivity of 0.2 g or the w
38、eights are no better than 0.2 g, the requirements of this paragraph can be met by continuingthe steady state for 36 days. An analytical balance that is much more sensitive will permit more rapid results on specimens below 1 perm 57ngPa-1s-1m-2 when the assembled dish is not excessively heavy.7. Mate
39、rials7.1 Desiccant and Water:7.1.1 For the Desiccant Method, anhydrous calcium chloride 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, shall be used (Note 3). It shall be dried at 400F 200C before use.NOTE 3If CaCl2 will react c
40、hemically on the specimen, an adsorbing desiccant such as silica gel, activated at 400F 200C, may be used; but themoisture gain by this desiccant during the test must be limited to 4 %.7.1.2 For the Water Method, distilled water shall be used in the test dish.7.2 SealantThe sealant used for attachin
41、g the specimen to the dish, in order to be suitable for this purpose, must be highlyresistant to the passage of water vapor (and water). It must not lose weight to, or gain weight from, the atmosphere in an amount,over the required period of time, that would affect the test result by more than 2 %.
42、It must not affect the vapor pressure in awater-filled dish. Molten asphalt or wax is required for permeance tests below 4 perms 230 ngm-2 s-1Pa-1. Sealing methods arediscussed in Appendix X2.8. Sampling8.1 The material shall be sampled in accordance with standard methods of sampling applicable to t
43、he material under test. Thesample shall be of uniform thickness. If the material is of nonsymmetrical construction, the two faces shall be designated bydistinguishing marks (for example, on a one-side-coated sample, “I” for the coated side and “II” for the uncoated side).9. Test Specimens9.1 Test sp
44、ecimens shall be representative of the material tested. When a product is designed for use in only one position, threespecimens shall be tested by the same method with the vapor flow in the designated direction. When the sides of a product areindistinguishable, three specimens shall be tested by the
45、 same method. When the sides of a product are different and either sidemay face the vapor source, four specimens shall be tested by the same method, two being tested with the vapor flow in eachdirection and so reported.9.2 A slab, produced and used as a laminate (such as a foamed plastic with natura
46、l “skins”) may be tested in the thickness ofuse. Alternatively, it may be sliced into two or more sheets, each being separately tested and so reported as provided in 9.4,provided also, that the “overlay upon the cup ledge” (6.1) of any laminate shall not exceed 18 in. 3 mm.9.3 When the material as u
47、sed has a pitted or textured surface, the tested thickness shall be that of use. When it is homogeneous,however, a thinner slice of the slab may be tested as provided in 9.4.9.4 In either case (9.2 or 9.3), the tested overall thickness, if less than that of use, shall be at least five times the sum
48、of themaximum pit depths in both its faces, and its tested permeance shall be not greater than 5 perms 300 ngm-2s-1Pa-1.9.5 For homogeneous (not laminated) materials with thickness greater than 12 in., the overall nominal thickness of eachspecimen shall be measured with an accuracy of 61 % of the re
49、ading at the center of each quadrant and the results averaged.9.6 When testing any material with a permeance less than 0.05 perms 3 ngm-2s-1Pa-1 or when testing a low permeancematerial that may be expected to lose or gain weight throughout the test (because of evaporation or oxidation), it is stronglyrecommended that an additional specimen, or “dummy,” be tested exactly like the others, except that no desiccant or water is putin the dish. Failure to u
