1、raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI Standards PublicationBS ISO 4919:2012Carpets Determination oftuft withdrawal forceBS ISO 4919:2012 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of ISO 4919:2012.The
2、 UK participation in its preparation was entrusted to TechnicalCommittee PRI/3/60, Textile in any case the average test time for the achievement of the maximum withdrawal force of the tufts and loops should be between 5 s and 10 s. This may be achieved in machines which would give very short test ti
3、mes, for example those using load cells, by inserting a spring between the loading mechanism and the specimen.The apparatus shall have a means of clamping a specimen of carpet to a base plate so that it is flat in a plane perpendicular to direction of pull upon the tuft or loop. The flat, horizontal
4、 part of the clamp which is brought into contact with the specimen during testing shall be at least 60 mm 60 mm, shall have a circular cut-out of at least 12 mm radius around the tuft or loop to be withdrawn and shall ISO 2012 All rights reserved 1BS ISO 4919:2012ISO 4919:2012(E)restrain the specime
5、n outside of this cut-out area (see Figure 1). The cut-out may have a throat to allow easier positioning of the specimen with the tuft grip or hook attached (see Figure 1).For cut pile carpets, a suitable means of selecting and gripping one end of a tuft shall be provided (for example locking surgic
6、al forceps) and for loop pile carpets, a suitable hook (for example a knitting-machine needle) is required. These tuft grips are attached to the upper jaw of the tensile apparatus.The load-sensing mechanism of the machine shall be calibrated with the tuft grip or hook in position.6 Atmosphere for co
7、nditioning and testingThe conditioning and testing atmosphere shall be the standard atmosphere for testing textiles defined in ISO 139, i.e. an atmosphere of relative humidity (65 4) % and a temperature of (20 2) C.7 Test samples and specimensTake samples from at least five places across the width o
8、f the carpet selected to be representative of the material under test in accordance with ISO 1957. Condition the samples for not less than 24 h in the standard atmosphere for testing textiles, as defined in Clause 6. Cut the specimens (one from each sample) to a size which is convenient for clamping
9、 on the testing machine and which will allow for at least 10 tufts to be withdrawn from each. No tufts shall be withdrawn from within 25 mm of the edge of a specimen or of any previously withdrawn tuft.8 Procedure8.1 Conduct the test in the standard atmosphere for testing textiles, as defined in Cla
10、use 6.8.2 For cut pile carpets, select one end of one tuft and attach the tuft grip. The selection of the tuft is easier if the specimen is bent backwards slightly to open out the tuft structure. Clamp the specimen firmly as described in Clause 5, and attach the tuft grip to the upper jaw. Set the m
11、achine in motion and completely withdraw the tuft along a path that is essentially perpendicular to that of the carpet specimen. Verify that only one tuft was withdrawn and register the maximum force recorded. If additional fibres from another tuft were gripped or if only part of the tuft was remove
12、d, ignore the result.In certain carpet constructions the selection of one tuft is impracticable, for example fine gauge carpets with more than one end per dent, or needle and fine gauge velour products. In such cases grip the minimum number of tufts that can be selected, and inspect the withdrawn un
13、it carefully to ensure that the required number of tufts has been isolated.If tufts have been selected from more than one dent, or if examination of the carpet shows that not the entire tuft has been removed; the results for such tufts should be disregarded.8.3 For loop pile carpets, select a suitab
14、le loop and engage the hook under the top of it. Attach the hook to the upper jaw. Set the machine in motion to move the hook along a path that is essentially perpendicular to that of the carpet specimen, and stop it as soon as slippage occurs in the bonds holding one of the loop sides. Verify that
15、only one loop was withdrawn and register the maximum force recorded.8.4 Where both cut and loop pile are present or where the specimen is composed of yarns of different linear densities, different fibres or different types, these shall be tested separately, and care should be taken to ensure that wh
16、ere possible the tufts or loops tested are surrounded by those of the same type. In some cases there may be no apparent physical differences in the yarns but real and statistically significant differences can be observed in the test results, justifying separation of the results into discrete populat
17、ions. In the case of patterned goods, for example crossover tufted carpets, the tufts may be identified by the position in which they appear in the pattern and/or the colour of the tufts. Only completely cut tufts or completely uncut loops should be tested.2 ISO 2012 All rights reservedBS ISO 4919:2
18、012ISO 4919:2012(E)8.5 Repeat the procedure for a minimum of 20 tufts or loops, spread evenly through the available samples taking into account the restriction of at least 25 mm between a previously withdrawn tuft or edge of the specimens. If the pile yarn breaks without pulling out the tuft or loop
19、, register the maximum force recorded and mark the result “broken”. Include this result in the number of valid tests but use it separately in calculations.NOTE The coefficient of variation of tuft withdrawal force is usually fairly large and may be of the order of 20 % to 30 %. Assuming these values
20、, if 20 tests are carried out, the 95 % confidence limits of the mean are about (9 to 13) % of the mean value.Greater accuracy may be obtained by testing more tufts; for example, if 50 tufts are tested, the 95 % confidence limits would be (6 to 9) % of the mean value.9 Expression of resultsCalculate
21、 the mean tuft withdrawal force, in newtons, and the coefficient of variation for all of the results, excluding any marked “broken”. Calculate the mean force for the broken tufts separately.If different types of pile or different yarns are tested separately and there is a marked difference between r
22、esults from different areas, this should be reported.10 Test reportThe test report shall include the following information:a) that the tests were performed in accordance with this International Standard;b) the date the tests were performed;c) the type of tensile machine used(CRE/CRL);d) the number o
23、f tufts or loops tested;e) the mean tuft withdrawal force and the coefficient of variation and, if applicable, the mean breaking force of the broken tufts, and the different areas and different types(see 8.4);f) if applicable, a statement that a multiple number of tufts was withdrawn, and a careful
24、description of the unit. ISO 2012 All rights reserved 3BS ISO 4919:2012ISO 4919:2012(E)Key1 loading mechanism 5 base plate2 spring (if necessary) 6 carpet specimen3 upper jaw 7 specimen clamp, dimensions as defined in 5.14 tuft grip or hookFigure 1 One possible form of flat horizontal mounting4 ISO
25、2012 All rights reservedBS ISO 4919:2012BS ISO 4919:2012ISO 4919:2012(E) ISO 2012 All rights reservedICS 59.080.60Price based on 4 pagesThis page deliberately left blankBSI is the independent national body responsible for preparing British Standards and other standards-related publications, informat
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