BSI Standards Publication BS EN 14617 13 2013 Agglomerated stone — Test methods Part 13 Determination of electrical resistivity BS EN 14617 13 2013 BRITISH STANDARD National foreword This British Stan[.]
BS EN 14617-13:2013 BSI Standards Publication Agglomerated stone — Test methods Part 13: Determination of electrical resistivity BS EN 14617-13:2013 BRITISH STANDARD National foreword This British Standard is the UK implementation of EN 14617-13:2013 It supersedes BS EN 14617-13:2005 which is withdrawn The UK participation in its preparation was entrusted to Technical Committee B/545, Natural stone A list of organizations represented on this committee can be obtained on request to its secretary This publication does not purport to include all the necessary provisions of a contract Users are responsible for its correct application © The British Standards Institution 2013 Published by BSI Standards Limited 2013 ISBN 978 580 79617 ICS 91.100.15 Compliance with a British Standard cannot confer immunity from legal obligations This British Standard was published under the authority of the Standards Policy and Strategy Committee on 30 April 2013 Amendments issued since publication Date Text affected BS EN 14617-13:2013 EN 14617-13 EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM April 2013 ICS 91.100.15 Supersedes EN 14617-13:2005 English Version Agglomerated stone - Test methods - Part 13: Determination of electrical resistivity Pierre agglomérée - Méthodes d'essai - Partie 13 : Détermination de la résistivité électrique Künstlich hergestellter Stein - Prüfverfahren - Teil 13: Bestimmung des spezifischen elektrischen Widerstands This European Standard was approved by CEN on March 2013 CEN members are bound to comply with the CEN/CENELEC 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 or 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 official 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, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United Kingdom EUROPEAN COMMITTEE FOR STANDARDIZATION COMITÉ EUROPÉEN DE NORMALISATION EUROPÄISCHES KOMITEE FÜR NORMUNG Management Centre: Avenue Marnix 17, B-1000 Brussels © 2013 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members Ref No EN 14617-13:2013: E BS EN 14617-13:2013 EN 14617-13:2013 (E) Contents Page Foreword Scope Normative references Principle 4 Terms and definitions and symbols Sampling and test specimen preparation Specimen conditioning Electrode system and measuring equipment .6 Procedure .6 Expression of results 10 Report .7 Annex A (informative) DC electrical conduction and polarisation phenomena in insulating materials 10 Annex B (informative) Statistical evaluation of test results 12 B.1 Scope 12 B.2 Symbols and definitions 12 B.3 Statistical evaluation of test results 12 Annex C (informative) Determination of DC volume resistance and resistivity and the corresponding electrical conductance and conductivity 14 C.1 Scope 14 C.2 Test specimen preparation 14 C.3 Specimen conditioning 14 C.4 Electrode system and measuring equipment 14 C.5 Procedure 14 C.6 Expression of results 15 C.7 Report 15 Bibliography 16 BS EN 14617-13:2013 EN 14617-13:2013 (E) Foreword This document (EN 14617-13:2013) has been prepared by Technical Committee CEN/TC 246 “Natural stones”, the secretariat of which is held by UNI 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 shall 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 14617-13:2005 Clauses 6, 7, 8, and 10 have been modified and a new Annex C has been added since the last edition of this European Standard This European Standard is one of a series of standards for test methods for agglomerated stones which includes the following: Part 1: Determination of apparent density and water absorption Part 2: Determination of flexural strength (bending) Part 4: Determination of the abrasion resistance Part 5: Determination of freeze and thaw resistance Part 6: Determination of thermal shock resistance Part 8: Determination of resistance to fixing (dowel hole) Part 9: Determination of impact resistance Part 10: Determination of chemical resistance Part 11: Determination of linear thermal expansion coefficient Part 12: Determination of dimensional stability Part 13: Determination of electrical resistivity Part 15: Determination of compressive strength Part 16: Determination of dimensions, geometric characteristics and surface quality of modular tiles According to the CEN-CENELEC Internal Regulations, the national standards organisations 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, 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 BS EN 14617-13:2013 EN 14617-13:2013 (E) Scope This European Standard covers the determination of DC insulation resistance, surface resistance and resistivity, and the corresponding electrical conductance and conductivity of specimens of agglomerated stone products conforming to the definition reported in EN 14618 These products are usually made by stone aggregates bound via either resin and filler or cement and water (paste components), or a mixture of polymer/cement and related addition (such as reinforcing fibres, electrically insulating/conducting fillers, etc.) Resistivity/conductivity may also be used as an indirect measure of some properties of agglomerated stone products (see Annex A - informative) Volume resistance and resistivity test method and the corresponding electrical conductance and conductivity of specimens of agglomerated stone products are also included (see Annex C - informative) Normative references Not applicable Principle The resistance/conductance of an agglomerated stone specimen is evaluated by the measurement of direct current (DC) flow in the specimen under specified conditions by appropriate electrode systems The resistivity/conductivity shall be calculated from specimen and electrode dimensions and shapes Terms and definitions and symbols 4.1 insulation resistance Ω Ω = ohm insulation resistance between two electrodes that are in electrical contact with an agglomerated stone specimen, calculated as the ratio of the direct voltage applied to the electrodes to the total current flowing between them Note to entry: specimen It is dependent upon the shape and size as well as the volume and surface resistance of the 4.2 surface resistance Rs (Ω) surface resistance between two electrodes that are in electrical contact with the surface of an agglomerated stone specimen, calculated as the ratio of the direct voltage applied to the electrodes to that portion of the current between them which is primarily distributed on the specimen surface and a thin material layer beneath the specimen surface Note to entry: Surface conductivity cannot be accurately known, only conventionally, because more or less volume contribution is usually involved in the measurement, depending on the nature of the specimen and environment 4.3 surface resistivity ρs (Ω) surface resistivity of the agglomerated stone material, which is calculated as the ratio of the potential gradient parallel to the current direction along its surface to the current per unit width of the surface BS EN 14617-13:2013 EN 14617-13:2013 (E) 4.4 surface conductivity γs (Ω-1) reciprocal of the surface resistivity 4.5 volume resistance Rv (Ω) volume resistance between two electrodes that are in electrical contact with a specimen, calculated as the ratio of the direct voltage applied to the electrodes to that portion of the current between them that flows only through the volume of the specimen 4.6 volume resistivity ρv (Ω·m) volume resistivity of the agglomerated stone material, which is calculated as the ratio of the potential gradient, parallel to the current direction in the material, to the current density EXAMPLE The charge carriers flow through the specimen, charge flowing in the unit time across the unit surface area normal to the current direction 4.7 volume conductivity γv (Ω-1·m-1 = S/m S = siemens) reciprocal of the volume resistivity Sampling and test specimen preparation Sampling is not the responsibility of the test laboratory, unless otherwise agreed It shall be appropriate to agglomerated stone consignment Whenever possible, the random sampling method shall be used Test specimens shall, however, be representative of the agglomerated stone sample and can be directly obtained from laboratory moulding and curing according to a detailed procedure (properly described in the test report) and/or core samples taken "in situ" and cut to proper size for the measuring apparatus The surfaces shall be honed or polished The test specimen may have any practical shape allowing the use of a proper three terminal electrodes system, according to the electrode assembly schematically shown in Figure for flat test specimens Sheet specimens like those illustrated in Figure should exhibit a thickness exceeding by 20 % the largest stone fragments size used in the agglomerated stone, and a diameter of 20 mm to 160 mm according to the resistivity of the tested material At least five test specimens shall be selected by sampling Specimen conditioning Measurements shall be made on either room-conditioned (23 ± 2) °C and (50 ± 10) % R.U or dried specimens In the first case, specimens shall be measured after proper conditioning (24 h at least) in the measuring environment according to other existing standard conditioning procedures In the latter case, specimen should be dried to constant weight in a circulating-air oven at (50 ± 2) °C (i.e difference < 0,1 % mass by consecutive weighing/ 24 h) After removing from the oven, specimens shall be cooled to room temperature in a dessicator under anhydrous atmosphere (anhydrous calcium chloride can be used) or in a vacuum enclosure until testing BS EN 14617-13:2013 EN 14617-13:2013 (E) Electrode system and measuring equipment Flat circular electrodes with the three-terminal configuration of Figure shall be used for the measurement of surface characteristics of agglomerated stone flat specimens The guard electrode may be omitted only for materials that have really ascertained negligible charge surface leakage A two-terminal configuration (i.e without the guard electrode) shall be used only for insulation resistance measurement To ensure an effective electrical contact of the measuring electrodes with the specimen surface, the three-terminal configuration on the specimen should be obtained by applying either a conducting layer (e.g colloidal graphite, metal spray or paint; conducting metal layer - gold, aluminium – by vacuum deposition, etc.) or placing a semiconducting sheet (e.g a soft polymeric or rubber semiconducting sheet) of the required geometry and size on the specimen surfaces and pressing it between the electrode system The voltmeter-ammeter method of Figure A.1 should be used whenever possible A constant voltage shall be supplied by a constant, stabilised voltage generator The current flowing through the specimen at a fixed, constant voltage may be measured by any equipment having the required sensitivity and accuracy (± 10 % is usually adequate) and data acquisition and treatment by personal computer Electrometers or direct-reading multimeters of suitable sensitivity may be used with the voltmeter-ammeter method of Figure 2, depending on the current range exhibited by the agglomerated stone specimen under testing Procedure At least five test specimens shall be measured Referring to Figure 1, measure the diameter d of the electrodes, the width g of the guard gap and the thickness th of the specimen with the appropriate measuring gauges (caliper and micrometer of proper sensitivity and accuracy are usually adequate) Make the electrical measurement with suitable devices having the required sensitivity and accuracy in a controlled atmosphere; the following standard conditions are suggested: for room-conditioned specimens, a temperature of (23 ± 2) °C and a relative humidity of (50 ± 10) %; for dried specimens, either a vacuum or dry environment Unless otherwise specified, a time of electrification of 60 s and an applied direct voltage of 100 V (or higher, depending on both specimen thickness and sample resistivity) shall be used Electrode position (Figure 1): Electrode n° 1: measuring or guarded electrode; Electrode n° 2: high voltage electrode; Electrode n° 3: guard electrode Expression of results Surface resistivity ρs and surface conductivity γs are calculated as a function of specimen shape at the measuring time t When measured in a vacuum enclosure, “intrinsic” (i.e without any environment influence) electrical resistivity/conductivity of agglomerated stones should be referred to For a flat circular agglomerated stone specimen, the following formula shall be used: ρs = 1/γs = R s.P/g [Ω] where: Rs is measured surface resistance in Ω; (1) BS EN 14617-13:2013 EN 14617-13:2013 (E) P is π D1 in m d0, D1, D2, g, th are the dimensions reported in Figure Calculate the mean value In addition, statistical treatment of the measurement data should be made to obtain standard deviation and coefficient of variation for the proper quantile factor according to existing procedures, when a normal distribution of data are assumed (see Annex B) 10 Report The report shall include the following: a) unique identification number of the report; b) the number and year of issue of this European Standard, i.e EN 14617-13:2013; c) the name and address of the test laboratory and the address where the test was carried out if different from the test laboratory; d) the name and address of the client; e) it is the responsibility of the client to supply the following information: 1) the name of the supplier; 2) the name of the person or organisation which carried out the sampling; 3) the surface finish of the specimens (if relevant to the test); 4) the nature of the binders; f) the date of delivery of the sample or of the specimens; g) the date when the test specimens were prepared (if relevant) and the date of testing; h) the number of specimens in the sample; i) the dimensions of the specimens; j) curing conditions and age of test specimens; k) dimensions of specimens according to either Figure or proper sample shape; l) type of surface finishing; m) type, shape and dimensions of electrical contacts; n) measuring conditions (temperature, relative humidity and applied electrical field); o) type of measuring equipment; p) applied voltage; q) time of voltage application; r) the number of test specimens measured; BS EN 14617-13:2013 EN 14617-13:2013 (E) s) surface resistivity value and statistical evaluation of the test results, if any; t) all deviations from the standard and their justification; u) remarks The test report shall contain the signatures and roles of the responsible(s) for the testing and the date of issue of the report It shall also state that the report should not be partially reproduced without written consent of the test laboratory or laboratories and the responsible(s) for the execution of the test D1 = (d0 + D2)/2 Key d0 th g D D1 > th g ≤ th internal diameter of the electrodes thickness of the specimen width of the guard gap measuring or guarded electrode high voltage electrode guard electrode diameter of the electrodes Figure — Three-terminal electrode configuration of measuring surface resistance/conductance BS EN 14617-13:2013 EN 14617-13:2013 (E) Key V S E Rc voltage specimen electrometer resistance Figure — Voltmeter-ammeter method using an electrometer (schematic) BS EN 14617-13:2013 EN 14617-13:2013 (E) Annex A (informative) DC electrical conduction and polarisation phenomena in insulating materials Resistivity/conductivity in electrically insulating bodies may be used as an indirect measure of static charging, moisture content, mechanical continuity and damages of various types, as well as of the effects of fibres (steel, glass, polymer, etc.), fillers (calcium carbonate, conducting, semiconducting and insulating powders, etc.), cement and polymers content on their properties Resin addition or cement substitution by resin in cement bound agglomerated stone products usually results in a remarkable conductivity decrease and may lead to accumulation of electrostatic charges on the body surfaces Polarised electrostatic charges are dangerous in risk environments, such as in the presence of flammable gases, vapours and fine powders suspended in air (e.g sugar, coal, flour, condensed milk, metal) where explosions may take place, in electronic equipments and plants (where blackout can arise), in surgery rooms and annexes (where some kinds of disinfectants and anaesthetics can cause fire and explosions) and similar ones On the other hand, decrease in conductivity may be favourable where high electrical insulation is required Measurement of electrical conductivity/resistivity of agglomerated stones proves therefore to be very useful for building and architectural use Resistivity/conductivity of insulating materials depends on temperature, humidity, electrification time and applied voltage These parameters should be accurately known to make the measured value reliable In particular, humidity content should be known, as it contributes to electrical conduction processes by releasing protons The electrical behaviour of insulating materials is indeed very different from that of electrically conducting and semiconducting materials The very low concentration of electronic charge carriers makes electrical conduction to be contributed only by ionic migration and polarised atomic and molecular groups vibration and local motion under the external electrical field These phenomena give rise to electrical conduction processes which greatly depend on time; macroscopic relaxation processes are then revealed by the measurement of transient electrical phenomena as a function of time in bulk material A steady state bulk polarisation in the material can be sketched as in Figure A.1 under a constant electrical field in a common voltmeter-ammeter testing method It should be noticed that the elementary charge separation depicted in the figure occurs in the material during a time largely depending on both the nature of charge carriers and material microstructure, leading to the so-called leakage current Ic∞ after a very long time Key V A voltmeter ammeter switch position switch position Figure A.1 — Electrical polarisation of an electrically insulating material under a constant electrical field 10 BS EN 14617-13:2013 EN 14617-13:2013 (E) Therefore, in principle, the charge flow, and hence the electrical current Ic flowing under an applied electrical voltage V, usually decreases with time as schematically reported in Figure A.2 Due to the contrasting effect of the increasing electrical polarisation within the material, this is the reason why any measurement should always be made at a known time (usually, one or two minutes after the electrical field application) The measured Ict at the measuring time t is usually a reliable first approximation of the leakage current Ic∞ Key V t lc ld voltage measuring time electric current discharge current Figure A.2 — Schematic transient polarisation phenomena as revealed by current changes after the constant voltage application (upper curve: switch position 1, Fig A.1) or removing (lower curve: switch position 2, Fig A.1) When the applied electrical field is removed and the electrodes on the measuring faces of the sample shortcircuited, the field arising in the materials from the previous electrical polarisation causes a discharge electric current Ic∞.flowing in the opposite direction in the sample; polarisation is higher the higher Ic∞.is The measured discharge current Idt at a measuring time t is again a reliable first approximation of the leakage discharge current Ic∞, representative of persisting polarisations in the material, a characteristic which shall be known in risk environments 11 BS EN 14617-13:2013 EN 14617-13:2013 (E) Annex B (informative) Statistical evaluation of test results B.1 Scope This Annex establishes a method for the statistical treatment of test results obtained following the agglomerated stone test method described in this document B.2 Symbols and definitions Measured values: Number of measured values: Mean value: Standard deviation Coefficient of variation Logarithmic mean Logarithmic standard deviation X , X , , X i , , X n n x = ∑ xi n i s=± v= ∑ (x i −x ) n −1 s (for individual values) x X ln = sln = ± ∑ i ln xi n ∑ (ln x i − x ln n −1 Maximum value max Minimum value Quantile factor k s given in table B.1 Lower expected value ) E = e xln −ks ⋅sln B.3 Statistical evaluation of test results For the calculation of the mean value x , the standard deviation distribution is assumed s and the coefficient of variation v , a normal For the calculation of the lower expected value E , a logarithmic normal distribution is assumed The lower expected value E corresponds to the % quantile of a logarithmic normal distribution for a confidence level of 75 % 12 BS EN 14617-13:2013 EN 14617-13:2013 (E) Table B.1 — Quantile factor (ks) in dependence on the number of measured values (n) in correspondence to the % quantile for a confidence level of 75 % n ks 3,15 2,68 2,46 2,34 2,25 2,19 2,14 10 2,10 15 1,99 20 1,93 30 1,87 40 1,83 50 1,81 … … 1,64 The following examples should help to clarify the method: Example 1: Calculation of mean value, standard deviation, maximum value and minimum value of measured values Measured number Measured value x Mean value 333 000 Standard deviation 2 150 Maximum value 400 200 Minimum value 000 300 350 400 147 Example 2: Calculation of mean value, standard deviation, coefficient of variation and lower expected value of 10 measured values Measured number Measured value x ln x Mean value 480 000 7,60 Logarithmic mean 7,807 2 150 7,67 Standard deviation 200 7,70 Logarithmic standard deviation 300 7,74 Variation coefficient 350 7,76 Number of measured values 400 7,78 Quantile factor 600 7,86 Lower expected value 750 7,92 900 7,97 10 150 8,06 363 0,143 0,15 10 2,10 819 13 BS EN 14617-13:2013 EN 14617-13:2013 (E) Annex C (informative) Determination of DC volume resistance and resistivity and the corresponding electrical conductance and conductivity C.1 Scope This test method covers the determination of DC insulation resistance, volume resistance and resistivity and the corresponding electrical conductance and conductivity This test informs about specific characteristics which usually are not relevant except for particular situations, such as raised access floors C.2 Test specimen preparation Sampling and test specimen preparation are detailed in Clause of this standard The same specimens can be used either to obtain surface or volume resistance and resistivity and the corresponding electrical conductance and conductivity C.3 Specimen conditioning Specimen conditioning is detailed in Clause of this standard The same room conditions are applicable to obtain surface or volume resistance and resistivity and the corresponding electrical conductance and conductivity C.4 Electrode system and measuring equipment Volume resistance/conductance shall be measured by the same electrode system as surface resistance/conductance For volume resistance/conductance tests, the guard electrode allows any contribution of the surface conductivity to be excluded in the measurement of volume conductivity C.5 Procedure As described in Clause of this standard except for electrode position: Electrode position (Figure 1): Electrode n° 1: measuring or guarded electrode; Electrode n° 2: guard electrode; Electrode n° 3: high voltage electrode 14 BS EN 14617-13:2013 EN 14617-13:2013 (E) C.6 Expression of results Volume resistivity ρv and volume conductivity γv, are calculated as a function of specimen shape at the measuring time t When measured in a vacuum enclosure, “intrinsic” (i.e without any environment influence) electrical resistivity/conductivity of agglomerated stones should be referred to For a flat circular agglomerated stone specimen the following formula shall be used: ρv = 1/γv = Rv.A/t [Ω·m] (2) where Rv is measured volume resistance in Ω; A is π (D1+g) /4 in m 2 d0, D1, D2, g, th are the dimensions reported in Figure Calculate the mean value In addition, statistical treatment of the measurement data should be made to obtain standard deviation and coefficient of variation for the proper quantile factor according to existing procedures, when a normal distribution of data are assumed (see Annex B) C.7 Report The report shall include the information detailed in Clause 10 of this standard except for: s) surface resistivity value and statistical evaluation of the test results, if any 15 BS EN 14617-13:2013 EN 14617-13:2013 (E) Bibliography [1] EN 1149-1, Protective clothing — Electrostatic properties — Part 1: Test method for measurement of surface resistivity [2] EN 12440, Natural stone — Denomination criteria [3] EN 14618, Agglomerated stone — Terminology and classification [4] ISO 9563, Belt drives — Electrical conductivity of antistatic endless synchronous belts — Characteristics and test method [5] ASTM Standard D257: Standard test methods for DC resistance or conductance of insulating materials [6] ASTM Standard D618: Standard practice for conditioning plastics for testing 16 This page deliberately left blank NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW British Standards Institution (BSI) BSI is the national body responsible for preparing British Standards and other standards-related publications, information and services BSI is incorporated by Royal Charter 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