1、raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI Standards PublicationBS EN ISO 21178:2013Light conveyor belts Determination of electricalresistancesBS EN ISO 21178:2013 BRITISH STANDARDNational forewordThis British Standard is the UK implementatio
2、n ofEN ISO 21178:2013. It supersedes BS EN ISO 21178:2006 which is withdrawn.The UK participation in its preparation was entrusted to TechnicalCommittee PRI/67, Conveyor belts.A list of organizations represented on this committee can beobtained on request to its secretary.This publication does not p
3、urport to include all the necessaryprovisions of a contract. Users are responsible for its correctapplication. The British Standards Institution 2013. Published by BSI StandardsLimited 2013 ISBN 978 0 580 77361 7 ICS 53.040.10 Compliance with a British Standard cannot confer immunity fromlegal oblig
4、ations.This British Standard was published under the authority of theStandards Policy and Strategy Committee on 30 April 2013. Amendments issued since publicationDate T e x t a f f e c t e dEUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN ISO 21178 April 2013 ICS 53.040.10 Supersedes EN ISO 2117
5、8:2006English Version Light conveyor belts - Determination of electrical resistances (ISO 21178:2013) Courroies transporteuses lgres - Dtermination des rsistances lectriques (ISO 21178:2013) This European Standard was approved by CEN on 4 March 2013. CEN members are bound to comply with the CEN/CENE
6、LEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre o
7、r to any CEN member. This European Standard exists in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management Centre has the same status as the off
8、icial versions. CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands
9、, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG Management Centre: Avenue Marnix 17, B-1000 Brussels 2013 CEN All rights of exploitatio
10、n in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN ISO 21178:2013: EBS EN ISO 21178:2013EN ISO 21178:2013 (E) 3 Foreword This document (EN ISO 21178:2013) has been prepared by Technical Committee ISO/TC 41 “Pulleys and belts (including veebelts)“ in collaboration
11、 with Technical Committee CEN/TC 188 “Conveyor belts” the secretariat of which is held by SNV. This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by October 2013, and conflicting national standards shal
12、l be withdrawn at the latest by October 2013. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN and/or CENELEC shall not be held responsible for identifying any or all such patent rights. This document supersedes EN ISO 21178:20
13、06. According to the CEN-CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France,
14、 Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom. Endorsement notice The text of ISO 21178:2013 has been approved by CEN as EN ISO 21
15、178:2013 without any modification. BS EN ISO 21178:2013ISO 21178:2013(E) ISO 2013 All rights reserved iiiContents PageForeword iv1 Scope . 12 Normative references 13 Symbols 14 Electrical surface resistances 24.1 Method A: measurement of surface resistance ROAomni-directionally 24.2 Method B: measur
16、ement of surface resistance ROBin longitudinal and transverse direction . 55 Electrical surface resistivity s. 75.1 General . 75.2 Principle 75.3 Apparatus 75.4 Preparation and preservation of test pieces prior to testing 95.5 Procedure 95.6 Expression of results . 105.7 Test report 106 Electrical v
17、olume resistances .106.1 Volume resistance RDperpendicular to plane of belt .106.2 Volume resistance, RDi, in longitudinal and transverse direction parallel to plane of belt 157 Electrical volume resistivity D187.1 Procedure . 187.2 Expression of results . 187.3 Test report 18Annex A (informative) C
18、omparative values for electrical resistances .19Bibliography .20BS EN ISO 21178:2013ISO 21178:2013(E)ForewordISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally
19、carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the wo
20、rk. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.The main task of technical committees is to prepare Intern
21、ational Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote.Attention is drawn to the possibility that some of the
22、elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights.ISO 21178 was prepared by Technical Committee ISO/TC 41, Pulleys and belts (including veebelts), Subcommittee SC 3, Conveyor belts.This second edition cancel
23、s and replaces the first edition (ISO 21178:2005), of which it constitutes a minor revision.iv ISO 2013 All rights reservedBS EN ISO 21178:2013INTERNATIONAL STANDARD ISO 21178:2013(E)Light conveyor belts Determination of electrical resistances1 ScopeThis International Standard specifies test methods
24、 for determining the electrical resistances of light conveyor belts according to ISO 21183-1. The resistances are surface resistance, volume resistance perpendicular to the belt plane, and longitudinal and transverse volume resistance parallel to the belt plane. This International Standard also spec
25、ifies two test methods for determining the surface resistivity and the volume resistivity.2 Normative referencesThe following documents, in whole or in part, are normatively referenced in this document and are indispensable to its application. For undated references, the latest edition of the refere
26、nced document (including any amendments) applies.ISO 18573, Conveyor belts Test atmospheres and conditioning periods3 SymbolsSymbol Quantity UnitROAElectrical surface resistance, method A ROBElectrical surface resistance, method B ROGElectrical surface resistance for the determination of sRDElectric
27、al volume resistance perpendicular to the plane of the belt RDiElectrical volume resistance in longitudinal and transverse direction parallel to the plane of the beltsElectrical surface resistivity DElectrical volume resistivity cmd1/2/3Diameter of electrode cmdmMiddle of the gap diameter cmg Width
28、of the gap cmA Surface of the electrode cm2h Thickness of test piece cmNOTE The SI unit of surface resistivity, s, is the ohm (). In practice, this is sometimes referred to as “ohm/square” or “/sq” or “/”. The size of the square is immaterial. ISO 2013 All rights reserved 1BS EN ISO 21178:2013ISO 21
29、178:2013(E)4 Electrical surface resistances4.1 Method A: measurement of surface resistance ROAomni-directionally4.1.1 ApplicabilityThis method is applicable to belts which are electrically two-dimensionally isotropic in the plane of the belt.4.1.2 PrincipleAn electric current of specified voltage is
30、 passed via electrodes through a suitably prepared test piece taken from the belt.4.1.3 Apparatus4.1.3.1 Sheet of insulating material, a little larger than the test piece4.1.3.2 Two cylindrical and coaxial brass electrodes, the base of one being circular and that of the other annular. The dimensions
31、 and masses are given in Figure 2. The bases of these electrodes shall be machined flat and polished.4.1.3.3 Flexible insulated wire, connected to each electrode.4.1.3.4 Ohmmeter, having a measuring range up to 1010 and accurate to within 5 %.4.1.3.5 Source of direct current, adjustable up to 500 V,
32、 and not permitting a current greater than 10 mA.NOTE The source of current can be either an accumulator or a rectified, stabilized a.c. power supply.4.1.4 Test piece4.1.4.1 MaterialTest piece material shall be new, unused (“virgin”), but shall not be tested sooner than five days after manufacture.
33、It shall be free from contamination and superficial damage.4.1.4.2 DimensionsThe test pieces shall be square, 300 mm 300 mm minimum, and shall be cut from the full thickness of the belt.4.1.4.3 NumberThree test pieces shall be taken. One test piece shall be taken from the middle of the belt, the oth
34、er two test pieces shall be taken 100 mm from each of the belt edges.4.1.4.4 CleaningIf necessary, clean both surfaces of the test pieces by rubbing with fullers earth (hydrated magnesium-aluminium silicate), for example, using a clean cloth. After cleaning away all traces of the powder, wipe the su
35、rface with a clean cloth moistened with distilled water and then dry with a clean cloth.2 ISO 2013 All rights reservedBS EN ISO 21178:2013ISO 21178:2013(E)4.1.4.5 ConditioningBefore testing, condition the test pieces in accordance with ISO 18573, Atmosphere B, for 24 h, except that, if the light con
36、veyor belt consists of materials with a high absorption of moisture, e.g. cotton or polyamide, condition the test piece for 48 h.4.1.4.6 PreparationPrepare the test pieces in the following manner after conditioning according to 4.1.4.5.To ensure good contact between electrodes and test piece a conta
37、ct agent shall be used. The electrical surface resistivity of the contact agent shall not be higher than 104. For checking this value, use the same electrode arrangement as described in Clause 5.NOTE A jelly having the following composition is suitable: anhydrous polyethylene glycol of molecular mas
38、s 600: 800 mg/g (mass fraction); water: 200 mg/g (mass fraction); potassium chloride: 10 mg/g (mass fraction); soft soap (pharmaceutical quality): 1 mg/g (mass fraction).If the surface of the test piece is flat, paint the contact agent onto the bottom surface of the cleaned electrodes. If the surfac
39、e of the test piece is textured, paint two areas of the test piece as shown in Figure 1. Take care to ensure the accuracy of the dimensions of the painted areas, although the symmetry of the centre is not critical. Carry out the test immediately after painting. If silver lacquer is used as the conta
40、ct agent, carry out the test after evaporating the solvent.4.1.5 ProcedureMeasure the temperature and relative humidity in the test room.Place the test piece on the sheet of insulating material, with the test surface upwards.Paint the test piece or bottom surface of the cleaned electrodes with conta
41、ct agent and let the solvent evaporate, if necessary.If necessary, clean the electrodes and place them on the test piece.Apply the test voltage to the electrodes, starting with a low voltage to protect very fine antistatic layers against damage.Read the value of the electrical resistance 1 min after
42、 applying the test voltage. ISO 2013 All rights reserved 3BS EN ISO 21178:2013ISO 21178:2013(E)Dimensions in millimetresKey1 contact agentFigure 1 Design to be painted on the test pieceDimensions in millimetresKey1 min. mass 115 g2 min. mass 900 gFigure 2 Electrodes4.1.6 Expression of resultsFor eac
43、h surface of the belt subjected to test, record the electrical resistance, in ohms, measured for each test piece, and calculate the mean of the values recorded for that surface for the three test pieces.Record the electrical resistance for the two surfaces of the belt separately.4 ISO 2013 All right
44、s reservedBS EN ISO 21178:2013ISO 21178:2013(E)4.1.7 Test reportThe test report shall include the following information:a) complete designation of the tested light conveyor belt material and the manufacturing date;b) reference to this International Standard, i.e. ISO 21178;c) test room temperature a
45、nd relative humidity;d) conditioning period;e) contact agent applied;f) voltage applied to the electrodes;g) results of the tests;h) date of test;i) any deviations from the standard test.4.2 Method B: measurement of surface resistance ROBin longitudinal and transverse direction4.2.1 ApplicabilityThi
46、s method is applicable to belts which have electrically varying properties in the plane of the belt, especially those where fabrics have conducting threads in the longitudinal direction which may be exposed on the belt surface.4.2.2 PrincipleAn electric current is passed via electrodes clamped in a
47、suitable arrangement to the surface of a test piece of the belt material.4.2.3 Apparatus (see Figure 3)4.2.3.1 Earthed screen plate4.2.3.2 Bottom plate, made of insulating material, such as polymethylmethacrylate, polytetrafluoroethylene or similar, having dimensions 600 mm 200 mm 20 mm.4.2.3.3 Bras
48、s electrodes, with connection points for the ohmmeter connecting cables, having a contact area of 100 mm 10 mm.4.2.3.4 Electrode holders4.2.3.5 Ohmmeter, having a measuring range up to 1010 and accurate to within 5 %.4.2.3.6 Source of direct current, adjustable up to 500 V, and not permitting a curr
49、ent greater than 10 mA.NOTE The source current can be either an accumulator or a rectified, stabilized a.c. power supply. ISO 2013 All rights reserved 5BS EN ISO 21178:2013ISO 21178:2013(E)Key1 screen plate, earthed2 bottom plate3 electrodes4 connection points5 electrode holder6 test pieceFigure 3 Test arrangement for measurement of electrical surface resistance ROB4.2.4 Test piece4.2.4.1 MaterialTest piece material shall be new, unused (“virgin”), but shall not be tested sooner than five days after manuf
