1、Designation: D737 04 (Reapproved 2016)D737 18Standard Test Method forAir Permeability of Textile Fabrics1This standard is issued under the fixed designation D737; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last rev
2、ision. 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 This test method covers the measurement
3、of the air permeability of textile fabrics.1.2 This test method applies to most fabrics including woven fabrics, nonwoven fabrics, air bag fabrics, blankets, nappedfabrics, knitted fabrics, layered fabrics, and pile fabrics. The fabrics may be untreated, heavily sized, coated, resin-treated, orother
4、wise treated.1.3 The values stated in SI units are to be regarded as the standard. The values stated in inch-pound units may be approximate.1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard
5、to establish appropriate safety safety, health, and healthenvironmental practices and determine theapplicability of regulatory limitations prior to use.1.5 This international standard was developed in accordance with internationally recognized principles on standardizationestablished in the Decision
6、 on Principles for the Development of International Standards, Guides and Recommendations issuedby the World Trade Organization Technical Barriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D123 Terminology Relating to TextilesD1776 Practice for Conditioning and Testing Text
7、ilesD2904 Practice for InterlaboratoryTesting of aTextileTest Method that Produces Normally Distributed Data (Withdrawn 2008)3D2906 Practice for Statements on Precision and Bias for Textiles (Withdrawn 2008)3D4850 Terminology Relating to Fabrics and Fabric Test MethodsF778 Methods for Gas Flow Resis
8、tance Testing of Filtration Media3. Terminology3.1 For definition of textile terms used in this test method: air permeability, and fabric, refer to Terminology D4850.3.2 For definitions of cross-machine direction; machine direction and other textile terms used in this test method, refer toTerminolog
9、y D123.4. Summary of Test Method4.1 The rate of air flow passing perpendicularly through a known area of fabric is adjusted to obtain a prescribed air pressuredifferential between the two fabric surfaces. From this rate of air flow, the air permeability of the fabric is determined.5. Significance an
10、d Use5.1 This test method is considered satisfactory for acceptance testing of commercial shipments since current estimates ofbetween-laboratory precision are acceptable, and this test method is used extensively in the trade for acceptance testing.1 This test method is under the jurisdiction ofASTM
11、Committee D13 on Textiles and is the direct responsibility of Subcommittee D13.59 on Fabric Test Methods, General.Current edition approved July 1, 2016Jan. 1, 2018. Published July 2016January 2018. Originally approved in 1943 . Last previous edition approved in 20122016 asD737 04(2012).(2016). DOI:
12、10.1520/D0737-04R16.10.1520/D0737-18.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.3 The last approved vers
13、ion of this historical standard is referenced on www.astm.org.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all ch
14、anges accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959.
15、United States15.1.1 If there are differences of practical significance between reported test results for two laboratories (or more), comparativetests should be performed to determine if there is a statistical bias between them, using competent statistical assistance. As aminimum, ensure the test sam
16、ples to be used are as homogeneous as possible, are drawn from the material from which the disparatetest results were obtained, and are randomly assigned in equal number to each laboratory for testing. The test results from the twolaboratories should be compared using a statistical test for unpaired
17、 data, at a probability level chosen prior to the testing series.If bias is found, either its cause must be found and corrected, or future test results for that material must be adjusted inconsideration of the known bias.5.2 Air permeability is an important factor in the performance of such textile
18、materials as gas filters, fabrics for air bags,clothing, mosquito netting, parachutes, sails, tentage, and vacuum cleaners. In filtration, for example, efficiency is directly relatedto air permeability.Air permeability also can be used to provide an indication of the breathability of weather-resista
19、nt and rainprooffabrics, or of coated fabrics in general, and to detect changes during the manufacturing process.5.3 Performance specifications, both industrial and military, have been prepared on the basis of air permeability and are usedin the purchase of fabrics where permeability is of interest.
20、5.4 Construction factors and finishing techniques can have an appreciable effect upon air permeability by causing a change inthe length of airflow paths through a fabric. Hot calendaring can be used to flatten fabric components, thus reducing airpermeability. Fabrics with different surface textures
21、on either side can have a different air permeability depending upon thedirection of air flow.5.4.1 For woven fabric, yarn twist also is important. As twist increases, the circularity and density of the yarn increases, thusreducing the yarn diameter and the cover factor and increasing the air permeab
22、ility. Yarn crimp and weave influence the shape andarea of the interstices between yarns and may permit yarns to extend easily. Such yarn extension would open up the fabric, increasethe free area, and increase the air permeability.5.4.2 Increasing yarn twist also may allow the more circular, high-de
23、nsity yarns to be packed closely together in a tightly wovenstructure with reduced air permeability. For example, a worsted gabardine fabric may have lower air permeability than a woolenhopsacking fabric.6. Apparatus6.1 Air Permeability Testing Apparatus4consisting of the following:6.1.1 Test Head t
24、hat provides a circular test area of 38.3 cm2 (5.93 in.2)6 0.3 %.NOTE 1Alternate test areas may 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 different thicknesses under a force of at least 50 6 5 N (11 6 1 lbf) to
25、 thetest head without distortion and minimal edge leakage underneath the test specimen.6.1.2.1 A suitable means to minimize edge leakage is to use a 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 un
26、derneath the test specimen.NOTE 2Since air leakage may affect test results, precautions must be taken, especially with very heavy or lofty fabrics, to prevent leakage. The useof a weighted ring and rubber gaskets on the clamp surfaces has been found to be helpful. Methods F778 describes a series of
27、usable clamping adaptionsto eliminate edge leakage. Gaskets should be used with caution because in some cases, and with repeated-use gaskets may deform resulting in a smallchange in test area. A weighted ring can be used with fabrics, such as knits or those that readily conform to the test head. The
28、 weighted ring is notrecommended for lofty or stiff fabric.6.1.3 Means for drawing a steady flow of air perpendicularly through the test area and for adjusting the airflow rate thatpreferably provides pressure differentials of between 100 and 2500 Pa (10 and 250 mm or 0.4 and 10 in. of water) betwee
29、n thetwo surfaces of the fabric being tested. At a minimum, the test apparatus must provide a pressure drop of 125 Pa (12.7 mm or 0.5in. of water) across the specimen.6.1.4 Pressure Gage or Manometer, connected to the test head underneath the test specimen to measure the pressure drop acrossthe test
30、 specimen in pascals (millimetres or inches of water) with an accuracy of 62 %.6.1.5 Flowmeter, volumetric counter or measuring aperture to 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 air permeabi
31、lity at the prescribed test pressure differential to verify theapparatus.6.1.7 Means of calculating and displaying the required results, such as scales, digital display, and computer-driven systems.6.2 Cutting Dies or Templates, to cut specimens having dimensions at least equal to the area of the cl
32、amping surfaces of thetest apparatus (optional).4 For additional information on obtaining apparatus, equipment, or supplies that may be suitable for use in this standard, please visit theASTM ManufacturersEquipmentDirectory at www.astm.org.D737 1827. Sampling and Test Specimens7.1 Lot SampleAs a lot
33、 sample for acceptance testing, randomly select the number of rolls or pieces of fabric directed in anapplicable material specification or other agreement between the purchaser and the supplier. Consider the rolls or pieces of fabricto be the primary sampling units. In the absence of such an agreeme
34、nt, take the number of fabric rolls or pieces specified in Table1.NOTE 3An adequate specification or other agreement between the purchaser and the supplier requires taking into account the variability between rollsor pieces of fabric and between specimens from a swatch from a roll or piece of fabric
35、 to provide a sampling plan with a meaningful producers risk,consumers risk, acceptable quality level, and limiting quality level.7.2 Laboratory SampleFor acceptance testing, take a swatch extending the width of the fabric and approximately 1 m (1 yd)along the lengthwise direction from each roll or
36、piece in the lot sample. For rolls of fabric, take a sample that will exclude fabricfrom the outer wrap of the roll or the inner wrap around the core of the roll of fabric.7.3 Test SpecimensFrom each laboratory sampling unit, take ten specimens unless otherwise agreed upon between purchaserand suppl
37、ier. Use the cutting die or template described in 6.2, or if practical, make air permeability tests of a textile fabric withoutcutting.7.3.1 Cutting Test SpecimensWhen cutting specimens, cut having dimensions at least equal to the area of the clampingmechanism. Label to maintain specimen identity.7.
38、3.1.1 Take specimens or position test areas representing a broad distribution across the length and width, preferably along thediagonal of the laboratory sample, and no nearer the edge than one tenth its width unless otherwise agreed upon between thepurchaser and supplier. Ensure specimens are free
39、of folds, creases, or wrinkles. Avoid getting oil, water, grease, and so forth, onthe specimens when handling.8. Preparation of Test Apparatus Apparatus, Calibration and CalibrationVerification8.1 Set-up procedures for machines from different manufacturers may vary. Prepare and verify calibration of
40、 the airpermeability tester as directed in the manufacturers instructions.8.2 When using microprocessor automatic data gathering systems, set the appropriate parameters as specified in themanufacturers instructions.8.3 For best results, level the test instrument.instrument according to the manufactu
41、rers recommendations.8.4 Verify calibration for the range and required water pressure differential that is expected for the material to betested.Verification checks, based upon frequency of your own quality procedures as per internal laboratory requirements, shall beperformed to ensure that the mach
42、ine is working correctly.8.4.1 Verification checks should be performed over the range and pressure differential being used during testing.9. Conditioning9.1 Precondition the specimens by bringing them to approximate moisture equilibrium in the standard atmosphere forpreconditioning textiles as speci
43、fied in Practice D1776.9.2 After preconditioning, bring the test specimens to moisture equilibrium for testing in the standard atmosphere for testingtextiles as specified in Practice D1776 or, if applicable, in the specified atmosphere in which the testing is to be performed.9.3 When it is known tha
44、t the material to be tested is not affected by heat or moisture, preconditioning and conditioning is notrequired when agreed upon in a material specification or contract order.10. Procedure10.1 Test the conditioned specimens in the standard atmosphere for testing textiles, which is 21 6 1C (70 6 2F)
45、 and 65 62 % relative humidity, unless otherwise specified in a material specification or contract order.10.2 Handle the test specimens carefully to avoid altering the natural state of the material.10.3 Place each test specimen onto the test head of the test instrument, and perform the test as speci
46、fied in the manufacturersoperating instructions.10.3.1 Place coated test specimens with the coated side down (towards low pressure side) to minimize edge leakage.TABLE 1 Number of Rolls or Pieces of Fabric in the Lot SampleNumber of Rolls or Pieces inLot, InclusiveNumber of Rolls or Piecesin Lot Sam
47、ple1 to 3 all4 to 24 425 to 50 5over 50 10 % to a maximum of 10 rolls or piecesD737 18310.4 Make tests at the water pressure differential specified in a material specification or contract order. In the absence of amaterial specification or contract order, use a water pressure differential of 125 Pa
48、(12.7 mm or 0.5 in. of water).10.5 Read and record the individual test results in SI units as cm3/s/cm2 and in inch-pound units as ft3/min/ft2 rounded to threesignificant digits.10.5.1 For special applications, the total edge leakage underneath and through the test specimen may be measured in a sepa
49、ratetest, with the test specimen covered by an airtight cover, and subtracted from the original test result to obtain the effective airpermeability.10.6 Remove the tested specimen and continue as directed in 10.3 10.5 until ten specimens have been tested for eachlaboratory sampling unit.10.6.1 When a 95 % confidence level for results has been agreed upon in a material specification or contract order, fewer testspecimens may be sufficient. In any event, the number of tests should be at least four.11. Calculation11.1 Air Permeability, Individual SpecimensCalcula
