1、BRITISH STANDARD BS6524:1984 Method for Determination of the surface resistivity of a textile fabric UDC677.017.57:537.311.3BS6524:1984 This British Standard, having been prepared under the directionof the Fibres, Yarns,Fabrics and ProductionStandards Committee,was published underthe authority of th
2、e BoardofBSI and comes intoeffecton 28 September1984 BSI 07-1999 The following BSI references relate to the work on this standard: Committee reference FBM/16 Draft for comment83/37608 DC ISBN 0 580 13967 0 Committees responsible for this British Standard The preparation of this British Standard was
3、entrusted by the Fibres, Yarns, Fabrics and Production Standards Committee (FBM/-) to Technical Committee FBM/16 upon which the following bodies were represented: British Textile Employers Association Confederation of British Wool Textiles Limited International Wool Secretariat Knitting Industries F
4、ederation Ltd. Man-made Fibres Producers Committee Manchester Testing House Ministry of Defence Soap and Detergent Industry Association Society of Dyers and Colourists Society of Motor Manufacturers and Traders Limited Textile Institute Textile Research Council The following bodies were also represe
5、nted in the drafting of the standard, through subcommittees and panels: Department of Health and Social Security Mail Order Traders Association of Great Britain Amendments issued since publication Amd. No. Date of issue CommentsBS6524:1984 BSI 07-1999 i Contents Page Committees responsible Inside fr
6、ont cover Foreword ii 1 Scope 1 2 Definitions 1 3 Principle 1 4 Apparatus and reagents 1 5 Specimens and conditioning 1 6 Procedure 2 7 Calculation and expression of results 2 8 Test report 2 Appendix A Applicability of the test method to unhomogeneous fabrics 4 Figure 1 Electrode assembly 3 Publica
7、tions referred to Inside back coverBS6524:1984 ii BSI 07-1999 Foreword This British Standard has been prepared under the direction of the Fibres, Yarns, Fabrics and Production Standards Committee. Textile fabrics for clothing, domestic or industrial uses may readily become charged during contact and
8、 separation from other materials or by the deposition of charged particles on their surfaces. The ability of the materials to dissipate or otherwise neutralize such charges by conduction is an indication of their antistatic behaviour and can be expressed in terms of the surface electrical resistivit
9、y of the material. The electrostatic properties of most textile fabrics are dependent on the relative humidity and temperature of the atmosphere in which they are conditioned. The lower the humidity the greater is the resistivity of the material. In testing fabrics for their electrical properties it
10、 is, therefore, important that they be conditioned at a specified humidity and temperature before starting the measurements. The surface resistivities of woven and knitted fabrics will usually depend on the direction of current flow in the specimen, and a mean value for all directions may be conveni
11、ently obtained by using concentric electrodes and applying an appropriate geometrical factor to convert the measured resistance into units of surface resistivity. For some textile materials (those known to be unhomogeneous in nature), surface resistivity is not a reliable indicator of “safe” electro
12、static behaviour. Such materials, and any textiles likely to be used in the presence of flammable or explosive substances should also be checked for electrostatic charging and voltage accumulation behaviour. A British Standard does not purport to include all the necessary provisions of a contract. U
13、sers of British Standards are responsible for their correct application. Compliance with a British 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 to4, an inside back cover and a b
14、ack cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.BS6524:1984 BSI 07-1999 1 1 Scope This British Standard describes a method for the determination of the surface resistivity
15、 of a textile fabric. It is intended for fabrics of moderate or low surface resistivity (less than10 13 7) and is not generally applicable to unhomogeneous fabrics. In certain cases however it may also be applied to coated fabrics and to fabrics containing small quantities of highly conducting fibre
16、: such special cases are covered in Appendix A. NOTEThe titles of the publications referred to in this standard are listed on the inside back cover. 2 Definitions For the purposes of this British Standard, the definitions given in BS5775-5 apply, together with the following. 2.1 unhomogeneous fabric
17、s fabrics that contain small quantities (lessthan10%) of conducting fibres, for example epitropic or metallic fibres; or fabrics that are coated or laminated with polymeric materials where the electrical properties of the components differ substantially from each other 2.2 surface resistivity the sp
18、ecific resistance along the surface of a textile fabric, expressed in ohms NOTEThe units for surface resistivity were formerly ohms per square, and refer to the resistance between opposite edges of a square in the surface of the material. Present usage requires the units to be ohms. This is correct
19、dimensionally, it being implicit by definition that the surface resistivity refers to the resistance between opposite edges of a square. 3 Principle The specimen of fabric to be tested is conditioned in an atmosphere of temperature and relative humidity appropriate to the conditions in which the fab
20、ric is to be used. The specimen is then placed on a base plate and an electrode assembly placed on top. A d.c. potential is applied to the electrode assembly and the resistance of the fabric is measured. 4 Apparatus and reagents 4.1 Electrodes, consisting of a cylindrical and an annular electrode co
21、ncentrically arranged within each other. Suitable electrodes, which are available commercially 1) , are shown in Figure 1. They are made of solid brass and are joined by annular pieces of insulating material of resistivity not less than10 14 7 determined in accordance with this method (see6.2). A br
22、ass guard ring is set in the middle of the insulating ring and both rings are recessed so that they do not contact the fabric surface. Concentric electrodes of dimensions other than those given in Figure 1 may be used and the appropriate factor (see clause6) applied in calculating the surface resist
23、ivity, providing that the diameter of the cylindrical electrode and the gapbetween the electrodes are both not lessthan20mm. 4.2 A flat base plate, of insulating material ofresistivity not less than10 14 7 (see6.2) anddimensions not less than250mm 250mm 10mm, used as a support for the fabric during
24、the measurement, and in turn rested on an earthed surface, e.g.a metal plate. 4.3 An ohmmeter, with a full scale deflection of not less than10 14 7 and accuracy 5% under an applied voltage of500V, or an electrometer of input impedance not less than10 14 7 and a separate d.c. source with an inbuilt s
25、afety resistor. 4.4 Paper tissues. 4.5 Propan-2-ol,1,1,2 trichloroethane or trichloroethylene, for use as a cleaning agent. CAUTION. 1,1,2 trichloroethane and trichloroethylene are toxic, irritant and narcotic in high concentrations. Avoid breathing the vapour. Avoid contact with skin, eyes and clot
26、hing. Propan-2-ol is highly flammable and toxic. Avoid breathing the vapour. Avoid contact with eyes and skin. 5 Specimens and conditioning A sample of fabric of sufficient size to obtain three representative measurements of resistivity shall be used. Three test specimens shall be cut, each of size
27、not less than250mm 250mm nor greater than the area of the base plate(4.2). No specimen shall be taken within a distance of50mm from any selvedge. 1) For information on the availability of the electrodes, apply to Enquiry Section (London), British Standards Institution, enclosing a stamped addressed
28、envelope for reply.BS6524:1984 2 BSI 07-1999 If a complete garment is to be tested, the base plate(4.2) shall be of sufficient size to accommodate the garment and three separate tests shall be carried out. NOTE 1For lined garments, each layer should be tested separately. The specimens or garment sha
29、ll be conditioned and tested at a temperature and relative humidity appropriate to the conditions in which they are to be used. For monitoring purposes an atmosphere of20 2 C and652% r.h. is widely used in the textile industry (see BS1051) but, in practice,20 2 C and402% r.h. are more relevant to ap
30、parel use where antistatic behaviour is important. The conditioning time prior to carrying out the test shall be not less than16h. NOTE 2New fabrics and garments may have finishes on them which reduce the resistivity of the untreated material and which are usually removed during washing or dry clean
31、ing. In some cases it may therefore be desirable to wash or dry clean the material before carrying out the test. An appropriate procedure should be chosen from BS4923 or BS4961, depending on the type of fibre and intended end-use of the material. 6 Procedure 6.1 Clean the lower surfaces of the elect
32、rodes(4.1) and the upper surface of the base plate(4.2) by wiping with a paper tissue(4.4) which has been moistened with one of the reagents(4.5). 6.2 Carry out a blank test using the procedure given in6.3 and6.4 but with no specimen in position, and calculate the resistivity of the insulating mater
33、ial. 6.3 Place the test specimen on the base plate(4.2) with the side that is being tested uppermost and place the electrode assembly on top. Connect the electrodes as shown in Figure 1. 6.4 Apply a potential of500V and after15 1s determine the resistance using the ohmmeter or electrometer(4.3). 6.5
34、 Repeat the procedure given in6.3 and6.4 on the two other test specimens or on two different parts of the garment. 7 Calculation and expression of results 7.1 Calculate the surface resistivity, (in ohms) for each of the three values of resistance using the equation: 7.2 Determine the mean of these t
35、hree values. 8 Test report The test report shall include the following information: a) a statement that the test was performed in accordance with this British Standard, i.e.BS6524; b) the individual surface resistivities (in ohms) for the three readings taken and the mean of these values; c) the dim
36、ensions of the electrodes used; d) whether or not the fabric had been washed or dry cleaned before testing, and, if so, details of the procedure used and reference to the appropriate British Standard; e) the temperature and relative humidity at which the test was carried out; f) details of any devia
37、tion from the specified procedure. where R is the measured resistance (in7); r 1 is the radius of the inner electrode (in mm); r 2 is the inner radius of the outer electrode (inmm). 2 R log e r 2 r 1 () - =BS6524:1984 BSI 07-1999 3 Figure 1 Electrode assemblyBS6524:1984 4 BSI 07-1999 Appendix A Appl
38、icability of the test method to unhomogeneous fabrics A.1 General Although this method of test is not generally applicable to unhomogeneous fabrics, guidance is given inA.2 andA.3 for special cases. A.2 Coated fabrics Coated fabrics for apparel use may be tested by this method if the resistivities o
39、f the coating and fabric are known separately. Since it is the resistivity of the side to be worn outermost which is of importance and the method always measures the less resistive component, it is only appropriate to test such fabrics if the resistivity of the outer layer is the lower, i.e.a coated
40、 fabric with the substrate worn outermost may be tested if the resistivity of the substrate is lower than that of the coating. Alternatively if the coating is worn outermost, the coating should be of lower resistivity than the substrate to ensure that the test is valid. A.3 Fabrics with conducting f
41、ibre With fabrics containing small quantities of conducting fibre the method will not be applicable when low values of resistivity (less than10 5 7) are consistently obtained, since these are due to conductive fibres at or near to the fabric surface spanning the electrodes, and are not representativ
42、e of the resistivity of the bulk of the fabric material. Also, in these cases, it would probably not be possible to maintain the applied potential at500V. Where conductive fibres do not span the electrodes the resistivity corresponds to that of the bulk of the fabric material; such values may be quo
43、ted, but the actual potential applied should be measured and reported as well.BS6524:1984 BSI 07-1999 Publications referred to BS1051, Glossary of terms relating to the conditioning, testing and mass determination of textiles. BS4923, Schedule of domestic washing and drying procedures for textile te
44、sting. BS4961, Methods for determination of dimensional stability of textiles to dry cleaning in tetrachloroethylene. BS5775, Quantities, units and symbols. BS5775-5, Electricity and magnetism. BS6524:1984 BSI 389 Chiswick High Road London W4 4AL BSIBritishStandardsInstitution BSI is the independent
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