ASTM D7407-2007 781 Standard Guide for Determining The Transmission of Gases Through Geomembranes《测定通过土工膜气体的传输用标准指南》.pdf

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1、Designation: D 7407 07Standard Guide for DeterminingThe Transmission of Gases Through Geomembranes1This standard is issued under the fixed designation D 7407; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revisio

2、n. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This guide is used as a discussion of the relevancy ofseveral methods to obtain the vapor transmission of geomem-branes.1.2 This

3、guide discusses applicable test methods, test mate-rials and conditions.1.3 The guide assumes the material being measured exhibitsFickian behavior.1.4 This guide does not purport to critique barrier systempermeability,1.5 The guide does not address transmission through seams,1.6 This standard does n

4、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 Standard

5、s:2D 1434 Test Method for Determining Gas PermeabilityCharacteristics of Plastic Film and SheetingD 3985 Test Method for Oxygen Gas Transmission RateThrough Plastic Film and Sheeting Using a CoulometricSensorD 4439 Terminology for GeosyntheticsE 96/E 96M Test Methods for Water Vapor Transmission ofM

6、aterialsF 1249 Test Method for Water Vapor Transmission RateThrough Plastic Film and Sheeting Using a ModulatedInfrared SensorF 1769 Test Method for Measurement of Diffusivity, Solu-bility, and Permeability of Organic Vapor Barriers Using aFlame Ionization Detector3F 1927 Test Method for Determinati

7、on of Oxygen GasTransmission Rate, Permeability and Permeance at Con-trolled Relative Humidity Through Barrier Materials Usinga Coulometric Detector3. Terminology3.1 Definitions:3.1.1 Definitions of terms applying to this test methodappear in Terminology D 44393.1.2 atmosphere for testing geosynthet

8、ics, nair main-tained at a relative humidity between 50 to 70 % and atemperature of 21 6 2C (70 6 4F).4. Summary of Guide4.1 This guide gives commentary as to the relevancy ofseveral methods to obtain Fickian diffusion through a geomem-brane. The tests evaluate gas and vapor transfer throughsemi-per

9、meable and permeable geomembranes. The data isimportant for design of containment systems.5. D 1434 Test Method for Determining Gas PermeabilityCharacteristics of Plastic Film and Sheeting5.1 This test method covers the estimation of the steady-state rate of transmission of a gas through plastics in

10、 the formof film, sheeting, laminates, and plastic-coated papers orfabrics. This test method provides for the determination of (1)gas transmission rate (GTR), (2) permeance, and, in the case ofhomogeneous materials, (3) permeability.5.2 Two procedures are provided: M Manometric and VVolumetric.5.3 T

11、his is an old test which relies of the physical measure-ment of gas through a geomembrane with respect to log time.This test has poor accuracy and takes a very long time.6. D 3985 Test Method for Oxygen Gas TransmissionRate Through Plastic Film and Sheeting Using aCoulometric Sensor6.1 This test met

12、hod covers a procedure for determinationof the steady-state rate of transmission of oxygen gas throughplastics in the form of film, sheeting, laminates, coextrusions,or plastic-coated papers or fabrics. It provides for the determi-nation of (1) oxygen gas transmission rate (O2GTR), (2) the1This guid

13、e is under the jurisdiction ofASTM Committee D35 on Geosyntheticsand is the direct responsibility of Subcommittee D35.10 on Geomembranes.Current edition approved Dec. 1, 2007. Published January 2008.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service

14、 at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Withdrawn.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.permeance of the film to oxygen gas

15、(PO2), and ( 3) oxygenpermeability coefficient (PO2) in the case of homogeneousmaterials. 7.2 7.36.2 This test method does not purport to be the only methodfor measurement of O2GTR. There may be other methods ofO2GTR determination that use other oxygen sensors andprocedures.6.3 This method is used i

16、n the food packaging industry wereplastic films rather than sheet are used. The method looks atoxygen transmission exclusively. Although interesting for foodapplications, results from this method may not correlate well togeomembrane performance in other non-food containmentapplications.7. E 96/E 96M

17、 Standard Test Methods for Water VaporTransmission of Materials7.1 These test methods cover the determination of watervapor 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

18、 products, wood products, and plastics. The test methodsare limited to specimens not over 1.25 in. (32 mm) inthickness. Two basic methods, the Desiccant Method and theWater Method, are provided for the measurement of per-meance, and two variations include service conditions with oneside wetted and s

19、ervice conditions with low humidity on oneside and high humidity on the other. Agreement should not beexpected between results obtained by different methods. Themethod should be selected that more nearly approaches theconditions of use.7.2 The values stated in inch-pound units are to be regardedsepa

20、rately as the standard. Within the text, the SI units areshown in parentheses. The values stated in each system are notexact equivalents; therefore each system must be used inde-pendently of the other. Combining values from two systemswill result in non-conformance with the standard. Howeverderived

21、results can be converted from one system to otherusing appropriate conversion factors (see Table 1).7.3 A cup is filled with distilled water leaving a small gap(0.759 to 0.259) of air space between the specimen and thewater. The cup is then sealed to prevent vapor loss exceptthrough the test sample.

22、 An initial weight is taken of theapparatus and then periodically weighed over time until resultsbecome linear. Caution must be used to assure that all weightloss is due to water vapor transmission through the specimen.7.4 For geomembrane: inverted cup technique is generallyconducted with water. Sta

23、ndard conditions are 50 % relativehumidity and 23 deg Celsius. The problem with the test is twofold, a) the mass loss is very small over time compared to themass of the apparatus being measured and b) the seal of theapparatus to the geomembrane needs to be less permeable thanthe geomembrane itself.

24、This second point is difficult toaccomplish for geomembranes greater than 20 mil thickness.8. F 1249 Standard Test Method for Water VaporTransmission Rate Through Plastic Film and SheetingUsing a Modulated Infrared Sensor8.1 This test method covers a procedure for determining therate of water vapor

25、transmission through flexible barriermaterials. The method is applicable to sheets and films up to 3mm (0.1 in.) in thickness, consisting of single or multilayersynthetic or natural polymers and foils, including coatedmaterials. It provides for the determination of ( 1) water vaportransmission rate

26、(WVTR), (2) the permeance of the film towater vapor, and (3) for homogeneous materials, water vaporpermeability coefficient.8.2 Values for water vapor permeance and water vaporpermeability must be used with caution. The inverse relation-ship of WVTR to thickness and the direct relationship ofWVTR to

27、 the partial pressure differential of water vapor maynot always apply.8.3 This is a good test for geomembranes unfortunately thedevice used for the method is proprietary.8.4 Like many of the methods critiqued, sealing issues ofthe device to the geomembrane exist.8.5 This high end test is sophisticat

28、ed and relinquishesresults quickly.9. F 1769 Standard Test Method for Measurement ofDiffusivity, Solubility, and Permeability of OrganicVapor Barriers Using a Flame Ionization Detector9.1 This test method covers the measurement of volatileorganic-vapor-barrier properties of films, plastic sheeting,c

29、oated papers, and laminates. The specific material propertiesmeasured include diffusivity, solubility, and permeability coef-ficients; parameter values which are required for the solution ofmass transfer problems associated with nonsteady state andsteady state conditions.9.2 Applicable test vapors i

30、nclude volatile organic com-pounds which are detectable by a flame ionization detector.Examples of applicable permeation compounds include sol-vents, organic film additives, flavor compounds, and aromacompounds.9.3 This test method assumes the material being measuredexhibits Fickian behavior and use

31、s the solutions to Ficks Lawsfor a planar surface as the data regression model.TABLE 1 Grouping of Test Methods for measuring GasTransmission with Respect to ApplicationASTM Method Oxygen OTRM Vapor MVTR Volatile Organic OTM MethaneD 1434 yes no no yesD 3985 yes no no noE 96 no yes no noF 1249 yes n

32、o no noF 1769 no no yes yesF 1927 yes no no noD74070729.4 This high end test that yields breakthrough time understeady state conditions. The accuracy of the test is an order ofmagnitude better than Test Method D 1434. However, there iscurrently only one commercial manufacturer of this equipment.10.

33、F 1927 Test Method for Determination of OxygenGas Transmission Rate, Permeability and Permeanceat Controlled Relative Humidity Through BarrierMaterials Using a Coulometric Detector10.1 This test method covers a procedure for determinationof the rate of transmission of oxygen gas, at steady-state, at

34、 agiven temperature and %RH level, through film, sheeting,laminates, co-extrusions, or plastic-coated papers or fabrics.This test method extends the common practice dealing withzero humidity or, at best, an assumed humidity. Humidity playsan important role in the oxygen gas transmission rate (O2GTR)

35、of many materials. This test method provides for the determi-nation of oxygen gas transmission rate (O2GTR), the per-meance of the film to oxygen gas (PO2), and oxygen perme-ability coefficient (PO2) in the case of homogeneousmaterials at given temperature and %RH levels(s).10.2 Oxygen is held on on

36、e side of the geomembrane whileNitrogen is held on the other. Specimen is in a controlledhumidity which is advantages for EVOH and Nylon.11. Keywords11.1 diffusion; geomembrane; film; permeability; per-meance; sheet; transmissionAPPENDIXX1. Examples Showing the Conversion of Permeance to Permeabilit

37、y of a GeomembraneX1.1 Water-Vapor Transmission. Since nothing isabsolutely impermeable, the assessment of the relativeimpermeability of geomembranes is an often discussedissue. The discussion is placed along with physicalproperties for want of a better location. The test itselfcould use an adapted

38、form of a geotechnicalengineering test using water as the permeant; however,this would be impractical. In such a case, the hydraulicheads required are so great that leaks or failedspecimens invariably result. At lower heads, long testtimes leading to evaporation problems become a majorobstacle. Inst

39、ead, a completely different approach istaken whereby water vapor is used as the permeantand diffusion is the fundamental mechanism ofpermeation. In the water-vapor transmission (WVT)test, a test specimen is sealed over an aluminum cupwith either water or a desiccant in it and a controlledrelative hu

40、midity difference across the geomembraneboundary is maintained. The ASTM test method iscovered under E96. With water in the cup (i.e., 100%relative humidity) and a lower relative humidityoutside of it, a weight loss over time can bemonitored. The required test time varies, but it isusually from 3 to

41、 40 days. Water vapor transmission,permeance, and (diffusion) permeability are thencalculated, as shown in Example 1 and 2.X1.2 Example 1 Calculate the WVT, permeance, and(diffusion) permeability of a 0.75 mm thick fPPgeomembrane of area 0.003 m2, and a forty daymass change of 0.216 g at an 80% rela

42、tive-humiditydifference while being maintained at a temperatureof 30C. Solution: Calculations proceed in stages asfollows.(a) Find the water vapor transmission:WVT5g 3 24t 3 awhere:g = weight change (g),t = time interval (h), anda = area of specimen (m2).WVT 50.216!24!40!24!0.003!5 1.80 g/m22 day(b)

43、 The permeance is given as:permeance 5WVTDP2WVTS R12 R2!where:DP = vapor pressure difference across membrane (mmHg),S = saturation vapor pressure at test temperature (mmHg),R1= relative humidity within cup, andR2= relative humidity outside cup (in environmentalchamber).permeance 5180321.00 2 0.20!5

44、0.0703 metric perm(c) (Diffusion) permeability = permeance 3 thickness =(0.0703)(0.75) = 0.0527 metric perm-mmNOTE X1.1This is a vapor-diffusion permeability following Fickiandiffusion and not the customary Darcian permeability as seen in thefollowing example. This is bad science, mixing the two the

45、ories istechnically undependable however, after numerous request we haveillustrated it below in Example 2.X1.3 Example 2 Using the information and data fromExample 1, calculate an equivalent hydraulicpermeability (i.e., a Darcian permeability, or hydraulicconductivity) of the geomembrane as is custo

46、marilymeasured in a geotechnical engineering test on claysoils. ,Solution: The parallel theories areDarcys formula for hydraulic permeability, q = kiA,D7407073qScm3sD 5 k ScmsDDhD1Scm H2Ocm soilD Acm2!and the WVT test for Fickian diffusion permeability,flowScm3sD5 kScm3cm22 s 2 cm 2 H2O/cm linerDpre

47、ssureSDcm H2Ocm linerDAcm2!Thus we must now modify the data used in Example 5.1 into the properunits.WVT 5 1.80gm2 day11024!24!60!60!5 2.08 3 1029gcm2 spermeance5WVTDP5WVTSR1 R2!52.08 3 1029321.00 0.20!5 0.812 3 10210gcm2 s mm Hgpermeability5 permeance 3 liner thickness5 0.812 3 102100.075!5 0.609 3

48、 10211gcm2 s mm Hg/cm liner5 6.09 3 10211gcm2 s cm Hg/cm linerIn terms of water pressure,hydraulic conductivity5 6.09 3 10211gcm2 s cm Hgcm liner13.6watermercury5 0.448 3 10211gcm2 s cm watercm liner gNow using the density of water,hydraulic conductivity5 0.448 3 10211gcm2 s cm watercm liner1.0gcm3a

49、nd canceling the units out, we get a comparable Darcian k-value for thegeomembrane ofk 5 0.5 3 10211cm/sor0.5 3 10213 m/sNOTE X1.2It should be mentioned, however, that the above describedtest method is extremely difficult to conduct for thick geomembranes andparticularly for HDPE since its WVT values are so low. The least amountof leakage around the test specimen-to-container seal will greatly distortthe resulting test results. As such the test is not recommended for generaluse and an entirely different configuration may be necessary, alth