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1、BRITISH STANDARD BS 2050:1978 Specification for Electrical resistance of conducting and antistatic products made from flexible polymeric material UDC 678 076:678.01:537.311:621.315.5 BS 2050:1978 This British Standard, having been prepared under the direction of the Plastics Standards Committee and
2、the Rubber Standards Committee, was published under the authority of the Executive Board on 28 February 1978 BSI 02-1999 First published December 1953 First revision February 1958 Second revision February 1961 Third revision February 1978 The following BSI references relate to the work on this stand
3、ard: Committee reference PLM/RUM/9 Draft for comment 75/52245 DC ISBN 0 580 10014 6 Cooperating organizations The Plastics Standards Committee and the Rubber Standards Committee, under whose direction this British Standard was prepared, consists of representatives from the following Government depar
4、tments and scientific and industrial organizations: British Plastics Federation* British Rubber Manufacturers Association* Chemical Industries Association Department of Industry (Chemicals and Textiles) Department of Industry (National Physical Laboratory) Department of the Environment (Building Res
5、earch Establishment) Electrical and Electronic and Insulation Association (BEAMA) Electrical Installation Equipment Manufacturers Association (BEAMA) Electrical Research Association* Engineering Equipment Users Association Institution of Production Engineers Ministry of Defence* Plastics and Rubber
6、Institute Post Office Royal Institute of British Architects Rubber and Plastics Research Association of Great Britain* Rubber Growers Association Society of Chemical Industry Society of Motor Manufacturers and Traders Limited The Malaysian Rubber Producers Research Association The organizations mark
7、ed with an asterisk in the above list, together with the following, were directly represented on the committee entrusted with the preparation of this British Standard: Association of Supervisory and Executive Engineers British Surgical Trades Association Incorporated Department of Health and Social
8、Security National Coal Board Tyre Manufacturers Conference (Service Committee) Amendments issued since publication Amd. No.Date of issueComments 4280July 1983 4499May 1984Indicated by a sideline in the margin BS 2050:1978 BSI 02-1999i Contents Page Cooperating organizationsInside front cover Forewor
9、dii 0Introduction 1 1Scope and field of application1 2References1 3Methods of test1 4Requirements2 5Marking2 6Number of tests3 Appendix A Methods for the determination of electrical resistance4 Table 1 Electrical requirements for hospital products2 Table 2 Electrical requirements for industrial prod
10、ucts3 Publications referred toInside back cover BS 2050:1978 ii BSI 02-1999 Foreword This standard has been prepared under the direction of the Plastics Standards Committee and the Rubber Standards Committee. It was originally published in 1953 and was revised in 1958 and 1961. The early editions co
11、vered conducting and antistatic rubber products deriving their electrical conductivity from carbon black. The 1961 edition and the present document have been extended to cover all types of flexible polymers and to permit the electrical conductivity to be derived from substances other than carbon bla
12、ck. This standard is based on the following three draft International Standards (ISO/DIS) amended in accordance with the United Kingdom comments submitted on these draft standards. ISO/DIS 2878, Antistatic and conductive rubber products Determination of electrical resistance. ISO/DIS 2882, Antistati
13、c and conductive products for hospital use Electrical resistance. ISO/DIS 2883, Antistatic and conductive products for industrial use Electrical resistance. In this revision the electrical requirements for hospital products have been segregated from those for industrial products. The list of industr
14、ial products has been augmented by the addition of synchronous belts, textile cots and aprons and by the expansion of the requirements for tyres, solid and pneumatic, for various applications. In addition the distinction made in the definitions in the earlier editions between conductive and antistat
15、ic products has been found to be misleading and has therefore been omitted from this revision. A British Standards 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 British Standard does
16、 not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages 1 to 6, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. Thi
17、s will be indicated in the amendment table on the inside front cover. BS 2050:1978 BSI 02-19991 0 Introduction The elimination or reduction of static charges is important in many applications. While the antistatic properties of an article are influenced by the electrostatic charging characteristics,
18、 the only way to ensure that charges are never developed on an object is generally to provide suitable leakage paths. This British Standard deals exclusively with products which may form part of such leakage paths. Polymeric compounds can be made into conductors of electricity by the incorporation i
19、n the compound of conducting particles, especially carbon black, or ionizable materials, or a combination of the two. The addition of carbon black to a polymer in sufficient quantities causes a conducting network of carbon particles to be formed within the mixture, and materials with a wide range of
20、 electrical conductivity can be produced. The carbon structure is sensitive to strain and the electrical resistance of the material depends on the degree of strain to which it has been subjected and the time and temperature history after strain. Materials made conducting by the addition of ionizable
21、 materials are generally of a higher order of magnitude of resistivity than those containing carbon but do not change appreciably in resistivity with strain. Their resistivity decreases with increase in temperature. During service the resistance of products made from both types of material may chang
22、e significantly and it is therefore necessary to ensure that the product is capable of fulfilling its designed function of dissipating electrostatic charges and conducting electricity during the whole of its life. In general the resistance of new products should not exceed 107 but in certain cases,
23、or with certain materials, higher values may be permitted. Values lower than 5 104 may not give adequate protection against fire from ignition of the rubber and against dangerous electric shock where there is any risk of apparatus becoming defective when operating at a voltage of 250 V to earth. A m
24、ethod for the measurement of the resistivity of specially prepared test pieces of antistatic and conducting rubber is described in BS 2044. 1 Scope and field of application 1.1 This British Standard specifies limits of electrical resistance for antistatic and conducting articles and products manufac
25、tured wholly or in part from natural or synthetic rubbers, from polyvinyl chloride, from other flexible polymeric materials or from mixtures of these. The electrical conductivity is derived from the addition of carbon black and/or other appropriate substances to the bulk of the material. This Britis
26、h Standard does not apply to: a) articles, the relevant surfaces of which are composed of mixtures of insulating and conducting areas; or to b) articles with a substantial surface area of insulating material, except for 1) hoses that have only a conductive lining or a conductive cover, and 2) footwe
27、ar, which does not normally have a conductive or antistatic upper. The resistance values given have been found suitable for certain products for hospital and industrial uses and are given as a guide. When British Standard product specifications for individual products have been issued, test methods
28、and resistance values given in the appropriate product specification should be used in preference to those given in this document. 1.2 This British Standard also describes methods of test to determine the electrical resistance of antistatic and conductive articles and products manufactured wholly or
29、 in part from a flexible polymeric material. The tests are carried out on the finished product using a defined system of electrodes by a system suited to factory inspection or service testing. These methods are not appropriate where the measured resistance is greater than 3 108. NOTEOnly if their su
30、itability has been established experimentally, should these methods of test be used for products not covered by this British Standard (e.g. products in which the electrical conductivity is not obtained by the addition of carbon black and/or other appropriate substances to the bulk material or which
31、have a substantial area of insulating material). 2 References The titles of the standards publications referred to in this standard are listed on the inside back cover. 3 Methods of test The product shall be tested by the appropriate method described in Appendix A. BS 2050:1978 2 BSI 02-1999 Table 1
32、 Electrical requirements for hospital products (See 1.1) 4 Requirements The electrical resistance of the product, as supplied new, shall comply with the requirements given in Table 1 or Table 2, as appropriate. 5 Marking Marking shall be indelible and clearly visible but of the smallest practicable
33、area to avoid the introduction of unnecessary insulating material. The position of the marking shall be such that it will not materially affect the electrical resistance of the discharge path. The marking of any sheeting or hose shall be applied throughout the length at intervals of not more than 0.
34、3 m for hospital products, but of not more than 3 m for industrial products, and 9 m for conveyor belting. NOTEIt is preferable that a floor should be marked with an installation test plate. For hospital products each item shall be marked in lemon yellow colour and, where practicable, it shall inclu
35、de the word “antistatic”. For industrial products each article without a lower limit specified for resistance shall be marked with the words “electrically conducting”, preferably in red. ItemProductElectrical resistance, Method of test (reference to clause in Appendix A) min.max. 1Anaesthetic airway
36、s 106 A.4.5 2Anaesthetic bellows106A.4.2 3Anaesthetic face pieces106A.4.2, A.4.3 4Anaesthetic tubing3 104 per m 106 per m A.4.4 A.4.5 5Breathing bags106A.4.7, A.4.8 6Flooring material5 1042 106A.4.1 7Footwear7.5 1045 107A.4.15 a) and b) 8Furniture buffers106A.4.10 9Furniture feet106A.4.9 10 Hose3 10
37、3 per m 106 per m A.4.5a A.4.6 11 Mattresses and pads104106A.4.2 12 Sheeting and articles made from sheeting (e.g. aprons) for hospital use: both surfaces to be tested106A.4.1 13 Tyres for castors and wheels for hospital furniture complying with the requirements of BS 2099104A.4.3 14 Non-wire-reinfo
38、rced hose with permanently attached metal end fittings 3 103 per m 106 per m A.4.14 15 Mouldings, small106A.4.2 NOTESafety codes for antistatic products for use in anaesthetizing areas for hospitals usually require that the resistance shall not exceed 108 at any time during their useful life. a See,
39、 however, A.4.6 if this method is used. BS 2050:1978 BSI 02-19993 6 Number of tests The number of tests shall be decided in accordance with the following criteria, in order of preference: a) by reference to a British Standard for the particular product, if one exists; b) by reference to the appropri
40、ate part of the appendix, if given there; c) by applying the following principles: 1) for small articles such as furniture feet and for articles used between defined contact points, one test shall be made; 2) for other articles such as tyres, sheeting, belting and pads, at least five tests shall be
41、made on different areas chosen so that the tests will be representative of the electrical properties of the whole article. All the test results shall be within the specified limits. Table 2 Electrical requirement for industrial products (See 1.1.) ItemProductElectrical resistance, Method of test (re
42、ference to clause in Appendix A) min.max. 1Flooring for explosive handling areas 5 104 A.4.2 2Flooring for antistatic purposes 5 104108 A.4.1 3Footwear, conducting (soles and heels), for explosive handling areas1.5 105A.4.15 a) 4Hose 3 103 per m 106 per m A.4.5a A.4.6 5Hose with conducting lining on
43、ly 3 103 per m 106 per m A.4.12 6Hose with conducting cover only 3 103 per m 106 per m A.4.13 7Non-wire-reinforced hose with permanently attached metal end fittings 3 103 per m 106 per m A.4.14 8Tyres for explosives handling vehicles 5 105 A.4.3 or A.4.11 9Antistatic tyres 104b107 A.4.3 or A.4.11 10
44、Textile cots and aprons 108 A.4.10 11Sheeting and articles made from sheeting; both surfaces to be tested106A.4.1 12Footwear, antistatic soles and heels 7.5 1045 107 A.4.15 a) and b) 13Transmission belting, flatc, where L is dry distance between electrodes W is width of belt A.4.16 14Wedge and V-bel
45、tsc, where L is dry distance between electrodes Z is sum of widths of the two driving surfaces of the belt As in BS 1440 and BS 3790 15Conveyor belts for mining 3 108 As in BS 3289 16Synchronous belts, where L is dry distance (measured in a straight line) between electrodes W is width of belt A.4.17
46、 a See, however, A.4.6 if this method is used. b This minimum value applies to new tyres; in use the resistance increases rapidly during the first few flexing and this low limit is necessary to ensure the retention of antistatic properties during a reasonable service life. c These values apply to be
47、lts made conductive by carbon black. They do not necessarily apply to belts made conductive in other ways. 105L 8W - - 5 106L 8Z - 5 106L 8W - BS 2050:1978 4 BSI 02-1999 Appendix A Methods for the determination of electrical resistance A.1 Apparatus A.1.1 Testing instruments. The test shall be made
48、with an instrument having a nominal open circuit voltage of 500 V d.c., preferably an insulation tester (ohm meter) or with any suitable instrument known to give comparable results. The instrument shall be sufficiently accurate to determine the resistance to within 10 % and shall not dissipate more
49、than 3 W in the test piece. NOTEThe insulation tester has an inherent characteristic of limited power output and also the voltage which it applies to the test piece decreases below its open circuit voltage at low resistance values of the test piece. This is a useful characteristic as it reduces the risk of shock and also of overheating the test piece. Insulation testers of this type may have manually or power driven generators or ma