1、Designation: D 737 04Standard 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 revision. A number in pare
2、ntheses indicates the year of last reapproval. Asuperscript epsilon (e) 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 This test method covers the measurement of the airpermeability of t
3、extile 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 sized, coated, resin-treated, or otherwise treated.1.3 The values s
4、tated 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 theresponsibility of the user of this standard to establish appro-priate safety
5、 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 Practice for Interlaboratory Testing of a Textile TestMethod That
6、 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 Media2.2 ASTM Adjuncts:TEX-PAC3NOTE 1TEX-PAC is a group of programs on floppy disks availablethrough AS
7、TM Headquarters, 100 Barr Harbor Drive, West Consho-hocken, PA 19428.3. Terminology3.1 For definition 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 t
8、his test method, referto Terminology D 123.4. Summary of Test Method4.1 The rate of air flow passing 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 fabri
9、c is determined.5. Significance and Use5.1 This test method is considered satisfactory for accep-tance 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
10、 differences of practical significance be-tween reported test results for two laboratories (or more),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 homogeneou
11、s as possible, are drawn from the materialfrom which the disparate test results were obtained, and arerandomly 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
12、 prior to the testing series. If bias isfound, either its cause must be found and corrected, or futuretest 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 fo
13、r airbags, clothing, mosquito netting, parachutes, sails, tentage, andvacuum cleaners. In filtration, for example, efficiency isdirectly related to air permeability.Air permeability also can beused to provide an indication of the breathability of weather-resistant and rainproof fabrics, or of coated
14、 fabrics in general,and to detect changes during the manufacturing process.1This 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 Dec. 1, 2004. Published January 2005
15、. Originallyapproved in 1943 . Last previous edition approved in 1996 as D 737 96.2For 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 Document Summary pag
16、e onthe ASTM website.3A PC program on floppy disk for Analyzing Committee D-13 interlaboratorydata are available from ASTM Headquarters. For a 312-in. disk, request PCN:12-429040-18. For a 514-in. disk, request PCN:12-429041-18.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West
17、Conshohocken, PA 19428-2959, United States.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
18、 effect upon 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 thedire
19、ction of 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 bet
20、ween yarns 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 reduc
21、ed air permeability. For example, aworsted gabardine fabric may have lower air permeability thana woolen hopsacking fabric.6. Apparatus6.1 Air Permeability Testing Apparatus4consisting of thefollowing:6.1.1 Test Head that provides a circular test area of 38.3cm2(5.93 in.2)6 0.3 %.NOTE 2Alternate tes
22、t 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 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.
23、2.1 A suitable 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 3Since air leakage may affect test results, precautions must b
24、etaken, especially 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. Test Method F 778 describes a series of usableclamping adaptions to eliminate edge leakage. Gaskets should be usedwith caution beca
25、use in some cases, and with repeated-use gaskets maydeform resulting in a small change in test area. A weighted ring can beused with fabrics, such as knits or those that readily conform to the testhead. The weighted ring is not recommended for lofty or stiff fabric.6.1.3 Means for drawing a steady f
26、low of air perpendicu-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
27、pressure drop 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, v
28、olumetric counter 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
29、and displaying 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 sa
30、mple for acceptance 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, ta
31、ke the number of fabric rollsor pieces specified in Table 1.NOTE 4An 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 prov
32、ide a sampling 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 th
33、e lot sample. 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
34、cutting die or 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.7.3.1.1 Take sp
35、ecimens 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 width unless otherwise agreed upon betweenthe purchaser and supplier. Ensure specimens are free of folds,4Suita
36、ble apparatus is commercially available.TABLE 1 Number of Rolls or Pieces of Fabric in the Lot SampleNumber of Rolls or Pieces inLot, InclusiveNumber of Rolls or Piecesin Lot Sample1to3 all4to24 425 to 50 5over 50 10 % to a maximum of 10 rolls or piecesD737042creases, or wrinkles. Avoid getting oil,
37、 water, grease, and soforth, on the specimens when handling.8. Preparation of Test Apparatus and Calibration8.1 Set-up procedures for machines from different manufac-turers may vary. Prepare and verify calibration of the airpermeability tester as directed in the manufacturers instruc-tions.8.2 When
38、using microprocessor automatic data gatheringsystems, set the appropriate parameters as specified in themanufacturers instructions.8.3 For best results, level the test instrument.8.4 Verify calibration for the range and required waterpressure differential that is expected for the material to beteste
39、d.9. Conditioning9.1 Precondition the specimens by bringing them to ap-proximate moisture equilibrium in the standard atmosphere forpreconditioning textiles as specified in Practice D 1776.9.2 After preconditioning, bring the test specimens to mois-ture equilibrium for testing in the standard atmosp
40、here 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 is known that the material to be tested is notaffected by heat or moisture, preconditioning and conditioningis not required when agreed upon in a
41、material specification orcontract order.10. Procedure10.1 Test the conditioned specimens in the standard atmo-sphere for testing textiles, which is 21 6 1C (70 6 2F) and65 6 2 % relative humidity, unless otherwise specified in amaterial specification or contract order.10.2 Handle the test specimens
42、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 as specified in the manufac-turers operating instructions.10.3.1 Place coated test specimens with the coated sidedown (towards low pressure side)
43、to minimize edge leakage.10.4 Make tests at the water pressure differential specifiedin a material specification or contract order. In the absence ofa material 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 individua
44、l 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 edge leakage un-derneath and through the test specimen may be measured in aseparate test, with the test specimen covered by an airtightcover, and
45、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 ten specimens have been tested for eachlaboratory sampling unit.10.6.1 When a 95 % confidence level for results has beenagreed upon in a materia
46、l specification or contract order, fewertest specimens may be sufficient. In any event, the number oftests should be at least four.11. Calculation11.1 Air Permeability, Individual SpecimensCalculate theair permeability of individual specimens using values readdirectly from the test instrument in SI
47、units as cm3/s/cm2and ininch-pound units as ft3/min/ft2, rounded to three significantdigits. When calculating air permeability results, follow themanufacturers instructions as applicable.NOTE 5For air permeability results obtained 600 m (2000 ft) abovesea level, correction factors may be required.11
48、.2 Air Permeability, AverageCalculate the average airpermeability for each laboratory sampling unit and for the lot.11.3 Standard Deviation, Coeffcient of VariationCalculate when requested.11.4 Computer-Processed DataWhen data are automati-cally computer-processed, calculations are generally contain
49、edin the associated software. It is recommended that computer-processed data be verified against known property values andits software described in the report.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
