1、BRITISH STANDARD BS 3424-26: 1990 Testing coated fabrics Part 26: Methods 29A, 29B, 29C and 29D. Methods for determination of resistance to water penetration and surface wetting IMPORTANT NOTE. It is recommended that this Part be read in conjunction with the information in Part 0 “Foreword and gener
2、al introduction”.BS3424-26:1990 This British Standard, having been prepared under the directionof the Rubber StandardsPolicy Committee, waspublished under the authorityof the Board of BSI andcomes into effect on 30 November1990 BSI 03-1999 First published, as BS 3424, October 1961 Second edition Oct
3、ober 1973 Third edition, as BS 3424-26, July1986 Fourth edition November 1990 The following BSI references relate to the work on this standard: Committee reference RUM/13 Draft for comment 88/35494 DC ISBN 0 580 18284 3 Amendments issued since publication Amd. No. Date of issue CommentsBS3424-26:199
4、0 BSI 03-1999 i Contents Page Committees responsible Inside front cover Foreword ii 1 Scope 1 2 Method 29A, Low range (large specimen) method 1 2.1 Principle 1 2.2 Apparatus 1 2.3 Test specimens 1 2.4 Procedure 1 2.5 Test report 2 3 Method 29B. High pressure method 2 3.1 Principle 2 3.2 Apparatus 2
5、3.3 Test specimens 2 3.4 Procedure 3 3.5 Test report 3 4 Method 29C. Low range (small specimen) method 3 4.1 Principle 3 4.2 Apparatus 3 4.3 Test specimens 3 4.4 Procedure 3 4.5 Test report 4 5 Method 29D. Surface wetting (spray test) 4 5.1 Principle 4 5.2 Apparatus and materials 4 5.3 Test specimen
6、s 5 5.4 Procedure 5 5.5 Test report 5 Appendix A ISO photographic scale 8 Figure 1 Schematic illustration of apparatus for Method 29A and Method 29C 2 Figure 2 Apparatus for high pressure method 4 Figure 3 Apparatus for spray test 6 Figure 4 Spray nozzle 7 Figure 5 ISO spray test rating chart based
7、on the AATCC photographic scale 8 Publications referred to Inside back coverBS3424-26:1990 ii BSI 03-1999 Foreword The method used for determination of resistance to water penetration or hydrostatic head testing will depend upon the type of coated fabric under test, the end use to which the material
8、 will be put, and the pressures to which it is considered most appropriate to subject the material under test. It is advisable to employ as large an area as possible in contact with the water, however, the availability of test equipment, economies of sampling and the limitations of commercial test e
9、quipment have to be taken into account. Because of these considerations it has been decided to provide four methods which will cater for most foreseeable requirements in terms of the widely divergent coated fabric types encountered in the coated fabrics industry, as well as taking account of the com
10、mercial test equipment available in the industry and the dependancy of the coated fabrics industry on the textile industry proper. Method 29A of BS 3424:1973 has been found to be, in the majority of cases, unwieldy, and takes up an unnecessary amount of laboratory space. This revision of method29A i
11、s the preferred method, using as it does, a large specimen of greater statistical significance. In BS3424-26:1986 the approach adopted in method29A and29C was to subject the test specimens to a steadily increasing pressure (the pumping rate being specified as10mL/min or60mL/min) until penetration of
12、 the first drop of water occurred. The pressure of water exerted at that point was then recorded. One of the objectives of this approach to hydrostatic head testing, was that with some variability in the performance of the coated fabric, especially after flexing or accelerated ageing, it was possibl
13、e to treat the results obtained statistically and assess the performance with some known level of confidence. Unfortunately the methods require constant attention by laboratory staff, and with the lower pumping rates and an extensive testing schedule such as that in BS3546, the staff time is quite c
14、onsiderable. It become difficult, with multiple head instruments, for the operator to note accurately the penetration pressure on individual specimens. With such a wide variety of coatings; from lightweight polyurethane (PU) to double texture polychloroprene (CR) coated fabrics, the range of hydrost
15、atic head performance values may be from approximately5kPa for crumple/flexed lightweight PU to over80kPa for most medium weight neoprenes. With pumping rates of10mL/min this represents penetration times of5min to nearly1.5h. As a consequence of these considerations it has been decided to adopt an a
16、dditional and more economic and practical approach to hydrostatic head testing in the form of pass/fail methods. There are, however, limitations to the pragmatic approach. Technologically justifiable times for the achievement of test pressure have been chosen so that the strains imposed on each grou
17、p of fabrics are as closely aligned as possible. This Part of BS3424supersedes BS3424-26:1986which is withdrawn. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a Brit
18、ish Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pagesi andii, pages1 to8, an inside back cover and a back cover. This stamdard has been updated (see copyright date) and may have had amendments inco
19、rporated. This will be indicated in the amendment table on theinside front cover.BS3424-26:1990 BSI 03-1999 1 1 Scope This Part of BS3424 describes three methods for the determination of the resistance of coated fabrics to water penetration and surface wetting (hydrostatic resistance), two of the me
20、thods each having two operational modes. A method for the assessment of the tendency to exhibit surface wetness is recommended as method29D. NOTEThe publications referred to in this standard are listed on the inside back page. 2 Method 29A. Low range (largespecimen) method 2.1 Principle A specimen o
21、f coated fabric is subjected to an increasing pressure of water on one face, under standard conditions, until a predetermined pressure specified in the coated fabric specification is obtained. The required pressure is maintained for a specified time or until penetration occurs, whichever is the less
22、er. The water pressure may be applied from below or from above the test specimen. The chosen alternative is specified in the test report. 2.2 Apparatus 2.2.1 A test rig 2.2.1.1 General. The apparatus consists of a well, fitted with a coaxial ring clamp to fasten the test specimen over the well. The
23、apparatus introduces water at room temperature from above or below the test specimen over a circular area of100cm 2 (approximately113mm diameter). The rubber tubing connecting the constant-level device and the well has an inside diameter of not less than6mm. NOTE 1If necessary soft rubber sealing ga
24、skets may be employed between the coated fabric specimen and the surfaces of the coaxial ring clamps in order to reduce the risk of damage to the test specimen by the clamps and to facilitate the testing of seams. In this respect rubber of designationZ40 complying with BS1154, having a hardness of a
25、pproximately40 IRHD (International Rubber Hardness Degree) and approximately1cm thick or1cm diameter has been found useful. Alternatively, a closed cell, cross-linked polyethylene foam having a density of45kg/m 3 to55kg/m 3 and approximately1cm thick has also been used. NOTE 2Results obtained using
26、the two different modes of operation in2.2.1.2 and2.2.1.3 on different materials exhibiting similar values do not reflect similar performances. NOTE 3A test rig is shown in Figure 1. 2.2.1.2 Pass/fail mode pumping rate. When operating the test rig for pass/fail tests, the water pressure specified in
27、 the coated fabric specification is attained in1min 10s for pressures less than30kPa 1)or in2min 20s for pressures greater than30kPa (305cmH 2 O). NOTEThis may readily be achieved by using mains water supply where suitable. 2.2.1.3 Index mode pumping rate. When operating the test rig for index mode,
28、 i.e.when subsequent statistical analysis is to be employed, water pressure is increased at the rate of0.98 0.049kPa/min (10 0.5cmH 2 O/min). 2.2.2 A means of measuring water pressure, such as either a manometer connected to the testing head(s), allowing water pressure up to19.6kPa(200cmH 2 O) to be
29、 read to an accuracy of 1%, or a pressure gauge, graduated in centimetres head of water or in kilopascals and complying with BS1780 with a maximum reading of at least100kPa (946cmH 2 O), is used as the means of measuring the water pressure applied to the test specimen. 2.3 Test specimens At least fi
30、ve specimens of coated fabric of diameter130mm to200mm, randomly selected from the sample, shall be tested. NOTEWhere the appropriate equipment is available the coated fabric may be tested without cutting specimens from the sample. 2.4 Procedure Wipe all surface water from the clamping surfaces. Cla
31、mp the test specimen in the test head so that the coated fabric is in a horizontal plane and in contact with the water, ensuring that no air is trapped between the coated fabric specimen and the water. The release valve shall be in the open position so that the clamping pressure does not exceed0.196
32、kPa(2cmH 2 O). Ensure that there is no leakage of water at the clamps. Close the release valve. Subject the test specimen immediately to increasing water pressure until the required operating pressure is obtained (see2.2.1). For pass/fail tests, maintain the hydrostatic pressure specified in the coa
33、ted fabric specification for2min if the required pressure is below30kPa or, for5min if the required pressure is above30kPa. The total duration of the test, if below30kPa, shall be not less than3min, or, if above30kPa, not less than7min. If any water appears on the surface of the specimen record a fa
34、ilure. For index methods, record the pressure at which water, if any, first appears on the surface of the specimen. Do not take into account droplets which are formed at the clamping edge and touching the clamping edge. 1) 1 cmH 2 O=98.066Pa.BS3424-26:1990 2 BSI 03-1999 2.5 Test report The test repo
35、rt shall include the following information: a) the description of the coated fabric; b) the rate of increase of water pressure; c) to which side of the coated fabric the water was applied; d) whether the water was applied from above or below the specimen; e) the individual test results; f) any devia
36、tion from the standard test procedure; g) reference to this method of test, i.e.method29A of BS3424-26:1990. NOTEFor information, the units are related as follows: 1inH 2 O=249.089Pa; 1cmH 2 O=98.066Pa; 1 psi=6.894 10 3 Pa; 1 psi=70.307cmH 2 O. 3 Method 29B. High pressure method 3.1 Principle A spec
37、imen of coated fabric is subjected to a predetermined pressure of water specified in the coated fabric specification on one face, under standard conditions for10min. The water pressure may be applied from below or from above the test specimen. The chosen alternative is specified in the test report.
38、3.2 Apparatus 3.2.1 A test rig, consisting of a well, fitted with a coaxial ring clamp to fasten the specimen over the well so that the specimen is clamped in a horizontal plane and such that it cannot slip in the clamps. The apparatus introduces water at room temperature to the test specimen over a
39、 circular area of683.49cm 2 , i.e.29.5cm diameter at such a rate that the water pressure specified in the coated fabric specification is attained in1min 10s. NOTE 1If necessary soft rubber sealing gaskets may be employed between the coated fabric specimen and the surfaces of the coaxial ring clamps
40、in order to reduce the risk of damage to the test specimen by the clamps. NOTE 2A test rig is shown in Figure 2. 3.2.2 A pressure gauge, complying with BS1780, graduated in kPa, with a maximum reading of at least1000kPa, is used as the means of measuring the water pressure applied to the test specim
41、en. 3.3 Test specimens At least three specimens of coated fabric, randomly selected from the sample shall be tested. NOTEThe coated fabric may be tested without cutting specimens from the sample, but if specimens are to be cut, they should be not less than350mm diameter. Figure 1 Schematic illustrat
42、ion of apparatus for Method29A andMethod 29CBS3424-26:1990 BSI 03-1999 3 3.4 Procedure Wipe all surface water from the clamping surfaces. Clamp the test specimen in the test head so that the coated fabric is in contact with the water, ensuring that no air is trapped between the coated fabric specime
43、n and the water. Ensure there is no leakage of water at the clamps. In the case of single face coated fabrics the face in contact with the water shall be specified in the test report. Increase the water pressure to that specified in the coated fabric specification. Maintain the specified pressure fo
44、r10min. Examine the surface of the test specimen in contact with the air for the presence of water globules or damp patches. 3.5 Test report The test report shall include the following: a) the description of the coated fabric; b) the rate of increase of water pressure; c) information on which side o
45、f the coated fabric specimen the water was applied to; d) whether the water was applied from above or below the coated fabric specimen; e) the individual test results; f) any deviation from the test procedure; g) reference to this method of test, i.e.method29B of BS3424-26:1990. 4 Method 29C. Low ra
46、nge (smallspecimen) method 4.1 Principle A specimen of coated fabric is subjected to an increasing pressure of water on one face, under standard conditions, until a predetermined pressure specified in the coated fabric specification is obtained. The required pressure is maintained for a specified ti
47、me or until penetration occurs whichever is the lesser. The water pressure may be applied from below or from above the test specimen. The chosen alternative is specified in the test report. 4.2 Apparatus 4.2.1 A test rig 4.2.1.1 General. The apparatus consists of a well, fitted with a coaxial ring c
48、lamp to fasten the test specimen over the well. The apparatus introduces water at room temperature from above or below the test specimen over a circular area of approximately19.63cm 2 (50mm diameter). 4.2.1.2 Pass/fail mode pumping rate. When operating the test rig for pass/fail tests, the water pre
49、ssure specified in the coated fabric specification shall be attained in1min 10s for pressures less than30kPa(305cmH 2 O) or in2min 20s for pressures greater than30kPa (305cmH 2 O). NOTE 1This may readily be achieved by using mains water supply where suitable. NOTE 2If necessary soft rubber sealing gaskets may be employed between the coated fabric specimen and the surfaces of the coaxial ring clamps in order to reduce the risk of damage to the test specimen by the clamps and to facilitate the testing of seams. In this respect rubber of designation Z40complying w
