1、Designation: D 737 04 (Reapproved 2008)1Standard Test Method forAir Permeability of Textile Fabrics1This standard is issued under the fixed designation D 737; 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 () indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defense.1NOTEEditorial changes were made in August 2008.1. Scope1.1 T
3、his test method covers the measurement of the airpermeability of textile fabrics.1.2 This test method applies to most fabrics includingwoven fabrics, nonwoven fabrics, air bag fabrics, blankets,napped fabrics, knitted fabrics, layered fabrics, and pile fabrics.The fabrics may be untreated, heavily s
4、ized, coated, resin-treated, or otherwise treated.1.3 The values stated in SI units are to be regarded as thestandard. The values stated in inch-pound units may beapproximate.1.4 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibi
5、lity 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:2D 123 Terminology Relating to TextilesD 1776 Practice for Conditioning and Testing TextilesD 2904
6、 Practice for Interlaboratory Testing of a Textile TestMethod that Produces Normally Distributed DataD 2906 Practice for Statements on Precision and Bias forTextilesD 4850 Terminology Relating to FabricF 778 Methods for Gas Flow Resistance Testing of Filtra-tion Media3. Terminology3.1 For definition
7、 of textile terms used in this test method:air permeability, and fabric, refer to Terminology D 4850.3.2 For definitions of cross-machine direction; machinedirection and other textile terms used in this test method, referto Terminology D 123.4. Summary of Test Method4.1 The rate of air flow passing
8、perpendicularly through aknown area of fabric is adjusted to obtain a prescribed airpressure differential between the two fabric surfaces. From thisrate of air flow, the air permeability of the fabric is determined.5. Significance and Use5.1 This test method is considered satisfactory for accep-tanc
9、e testing of commercial shipments since current estimatesof between-laboratory precision are acceptable, and this testmethod is used extensively in the trade for acceptance testing.5.1.1 If there are differences of practical significance be-tween reported test results for two laboratories (or more),
10、comparative tests should be performed to determine if there isa statistical bias between them, using competent statisticalassistance. As a minimum, ensure the test samples to be usedare as homogeneous as possible, are drawn from the materialfrom which the disparate test results were obtained, and ar
11、erandomly assigned in equal number to each laboratory fortesting. The test results from the two laboratories should becompared using a statistical test for unpaired data, at aprobability level chosen prior to the testing series. If bias isfound, either its cause must be found and corrected, or futur
12、etest results for that material must be adjusted in considerationof the known bias.5.2 Air permeability is an important factor in the perfor-mance of such textile materials as gas filters, fabrics for airbags, clothing, mosquito netting, parachutes, sails, tentage, andvacuum cleaners. In filtration,
13、 for example, efficiency isdirectly related to air permeability.Air permeability also can be1This test method is under the jurisdiction of ASTM Committee D13 on Textilesand is the direct responsibility of Subcommittee D13.59 on Fabric Test Methods,General.Current edition approved July 1, 2008. Publi
14、shed August 2008. Originallyapproved in 1943 . Last previous edition approved in 2004 as D 737 04.2For 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 Docu
15、ment Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.used to provide an indication of the breathability of weather-resistant and rainproof fabrics, or of coated fabrics in general,and to detect changes
16、 during the manufacturing process.5.3 Performance specifications, both industrial and military,have been prepared on the basis of air permeability and areused in the purchase of fabrics where permeability is ofinterest.5.4 Construction factors and finishing techniques can havean appreciable effect u
17、pon air permeability by causing a changein the length of airflow paths through a fabric. Hot calendaringcan be used to flatten fabric components, thus reducing airpermeability. Fabrics with different surface textures on eitherside can have a different air permeability depending upon thedirection of
18、air flow.5.4.1 For woven fabric, yarn twist also is important.As twistincreases, the circularity and density of the yarn increases, thusreducing the yarn diameter and the cover factor and increasingthe air permeability. Yarn crimp and weave influence the shapeand area of the interstices between yarn
19、s and may permit yarnsto extend easily. Such yarn extension would open up the fabric,increase the free area, and increase the air permeability.5.4.2 Increasing yarn twist also may allow the more circular,high-density yarns to be packed closely together in a tightlywoven structure with reduced air pe
20、rmeability. For example, aworsted gabardine fabric may have lower air permeability thana woolen hopsacking fabric.6. Apparatus6.1 Air Permeability Testing Apparatus3consisting of thefollowing:6.1.1 Test Head that provides a circular test area of 38.3cm2(5.93 in.2)6 0.3 %.NOTE 1Alternate test areas m
21、ay be used, such as 5 cm2(0.75 in.2),6.45 cm2(1.0 in.2), and 100 cm2(15.5 in.2).6.1.2 Clamping System to Secure Test Specimens, of differ-ent thicknesses under a force of at least 50 6 5N(116 1 lbf)to the test head without distortion and minimal edge leakageunderneath the test specimen.6.1.2.1 A sui
22、table means to minimize edge leakage is to usea 55 Type A durometer hardness polychloroprene (neoprene)clamping ring 20 mm (0.75 in.) wide and 3 mm (0.125 in.)thick around the test area above and underneath the testspecimen.NOTE 2Since air leakage may affect test results, precautions must betaken, e
23、specially with very heavy or lofty fabrics, to prevent leakage. Theuse of a weighted ring and rubber gaskets on the clamp surfaces has beenfound to be helpful. Methods F 778 describes a series of usable clampingadaptions to eliminate edge leakage. Gaskets should be used with cautionbecause in some c
24、ases, and with repeated-use gaskets may deformresulting in a small change in test area. A weighted ring can be used withfabrics, such as knits or those that readily conform to the test head. Theweighted ring is not recommended for lofty or stiff fabric.6.1.3 Means for drawing a steady flow of air pe
25、rpendicu-larly through the test area and for adjusting the airflow rate thatpreferably provides pressure differentials of between 100 and2500 Pa (10 and 250 mm or 0.4 and 10 in. of water) betweenthe two surfaces of the fabric being tested. At a minimum, thetest apparatus must provide a pressure drop
26、 of 125 Pa (12.7mm or 0.5 in. of water) across the specimen.6.1.4 Pressure Gage or Manometer, connected to the testhead underneath the test specimen to measure the pressure dropacross the test specimen in pascals (millimetres or inches) ofwater with an accuracy of 62%.6.1.5 Flowmeter, volumetric cou
27、nter or measuring apertureto measure air velocity through the test area in cm3/s/cm2(ft3/min/ft2) with an accuracy of 62%.6.1.6 Calibration Plate, or other means, with a known airpermeability at the prescribed test pressure differential to verifythe apparatus.6.1.7 Means of calculating and displayin
28、g the requiredresults, such as scales, digital display, and computer-drivensystems.6.2 Cutting Dies or Templates, to cut specimens havingdimensions at least equal to the area of the clamping surfacesof the test apparatus (optional).7. Sampling and Test Specimens7.1 Lot SampleAs a lot sample for acce
29、ptance testing,randomly select the number of rolls or pieces of fabric directedin an applicable material specification or other agreementbetween the purchaser and the supplier. Consider the rolls orpieces of fabric to be the primary sampling units. In theabsence of such an agreement, take the number
30、 of fabric rollsor pieces specified in Table 1.NOTE 3An adequate specification or other agreement between thepurchaser and the supplier requires taking into account the variabilitybetween rolls or pieces of fabric and between specimens from a swatchfrom a roll or piece of fabric to provide a samplin
31、g plan with a meaningfulproducers risk, consumers risk, acceptable quality level, and limitingquality level.7.2 Laboratory SampleFor acceptance testing, take aswatch extending the width of the fabric and approximately 1m (1 yd) along the lengthwise direction from each roll or piecein the lot sample.
32、 For rolls of fabric, take a sample that willexclude fabric from the outer wrap of the roll or the inner wraparound the core of the roll of fabric.7.3 Test SpecimensFrom each laboratory sampling unit,take ten specimens unless otherwise agreed upon betweenpurchaser and supplier. Use the cutting die o
33、r template de-scribed in 6.2, or if practical, make air permeability tests of atextile fabric without cutting.7.3.1 Cutting Test SpecimensWhen cutting specimens, cuthaving dimensions at least equal to the area of the clampingmechanism. Label to maintain specimen identity.3: For additional informatio
34、n on obtaining apparatus, equipment, or supplies thatmay be suitable for use in this standard, please visit the ASTM ManufacturersEquipment Directory at www.astm.org.TABLE 1 Number of Rolls or Pieces of Fabric in the Lot SampleNumber of Rolls or Pieces inLot, InclusiveNumber of Rolls or Piecesin Lot
35、 Sample1to3 all4to24 425 to 50 5over 50 10 % to a maximum of 10 rolls or piecesD 737 04 (2008)127.3.1.1 Take specimens or position test areas representing abroad distribution across the length and width, preferably alongthe diagonal of the laboratory sample, and no nearer the edgethan one tenth its
36、width unless otherwise agreed upon betweenthe purchaser and supplier. Ensure specimens are free of folds,creases, or wrinkles. Avoid getting oil, water, grease, and soforth, on the specimens when handling.8. Preparation of Test Apparatus and Calibration8.1 Set-up procedures for machines from differe
37、nt manufac-turers may vary. Prepare and verify calibration of the airpermeability tester as directed in the manufacturers instruc-tions.8.2 When using microprocessor automatic data gatheringsystems, set the appropriate parameters as specified in themanufacturers instructions.8.3 For best results, le
38、vel the test instrument.8.4 Verify calibration for the range and required waterpressure differential that is expected for the material to betested.9. Conditioning9.1 Precondition the specimens by bringing them to ap-proximate moisture equilibrium in the standard atmosphere forpreconditioning textile
39、s as specified in Practice D 1776.9.2 After preconditioning, bring the test specimens to mois-ture equilibrium for testing in the standard atmosphere fortesting textiles as specified in Practice D 1776 or, if applicable,in the specified atmosphere in which the testing is to beperformed.9.3 When it i
40、s known that the material to be tested is notaffected by heat or moisture, preconditioning and conditioningis not required when agreed upon in a material specification orcontract order.10. Procedure10.1 Test the conditioned specimens in the standard atmo-sphere for testing textiles, which is 21 6 1C
41、 (70 6 2F) and65 6 2 % relative humidity, unless otherwise specified in amaterial specification or contract order.10.2 Handle the test specimens carefully to avoid alteringthe natural state of the material.10.3 Place each test specimen onto the test head of the testinstrument, and perform the test a
42、s specified in the manufac-turers operating instructions.10.3.1 Place coated test specimens with the coated sidedown (towards low pressure side) to minimize edge leakage.10.4 Make tests at the water pressure differential specifiedin a material specification or contract order. In the absence ofa mate
43、rial specification or contract order, use a water pressuredifferential of 125 Pa (12.7 mm or 0.5 in. of water).10.5 Read and record the individual test results in SI units ascm3/s/cm2and in inch-pound units as ft3/min/ft2rounded tothree significant digits.10.5.1 For special applications, the total e
44、dge leakage un-derneath and through the test specimen may be measured in aseparate test, with the test specimen covered by an airtightcover, and subtracted from the original test result to obtain theeffective air permeability.10.6 Remove the tested specimen and continue as directedin 10.3-10.5 until
45、 ten specimens have been tested for eachlaboratory sampling unit.10.6.1 When a 95 % confidence level for results has beenagreed upon in a material specification or contract order, fewertest specimens may be sufficient. In any event, the number oftests should be at least four.11. Calculation11.1 Air
46、Permeability, Individual SpecimensCalculate theair permeability of individual specimens using values readdirectly from the test instrument in SI units as cm3/s/cm2and ininch-pound units as ft3/min/ft2, rounded to three significantdigits. When calculating air permeability results, follow themanufactu
47、rers instructions as applicable.NOTE 4For air permeability results obtained 600 m (2000 ft) abovesea level, correction factors may be required.11.2 Air Permeability, AverageCalculate the average airpermeability for each laboratory sampling unit and for the lot.11.3 Standard Deviation, Coeffcient of
48、VariationCalculate when requested.11.4 Computer-Processed DataWhen data are automati-cally computer-processed, calculations are generally containedin the associated software. It is recommended that computer-processed data be verified against known property values andits software described in the rep
49、ort.12. Report12.1 Report that the air permeability was determined inaccordance with Test Method D 737. Describe the material orproduct sampled and the method of sampling used.12.2 Report the following information for each laboratorysampling unit and for the lot as applicable to a materialspecification or contract order:12.2.1 Air permeability.12.2.2 When calculated, the standard deviation or the coef-ficient of variation.12.2.3 Pressure differential between the fabric surfaces.12.2.4 For computer-processed data, identify the program(software) used.12.2.5 M
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