BS ISO 17308-2015 Petroleum products and other liquids Ethanol Determination of electrical conductivity《石油产品和其他流体 乙醇 导电性的测定》.pdf

1、BSI Standards PublicationBS ISO 17308:2015Petroleum products andother liquids Ethanol Determination of electricalconductivityBS ISO 17308:2015 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of ISO 17308:2015.The UK participation in its preparation was entrusted to Te

2、chnicalCommittee PTI/13, Petroleum Testing and Terminology.A list of organizations represented on this committee can beobtained on request to its secretary.This publication does not purport to include all the necessaryprovisions of a contract. Users are responsible for its correctapplication. The Br

3、itish Standards Institution 2015. Published by BSI StandardsLimited 2015ISBN 978 0 580 83823 1ICS 75.160.20Compliance with a British Standard cannot confer immunity fromlegal obligations.This British Standard was published under the authority of theStandards Policy and Strategy Committee on 31 Janua

4、ry 2015.Amendments issued since publicationDate Text affectedBS ISO 17308:2015 ISO 2015Petroleum products and other liquids Ethanol Determination of electrical conductivityProduits ptroliers et autres liquides thanol Dtermination de la conductivit lectriqueINTERNATIONAL STANDARDISO17308First edition

5、2015-01-15Reference numberISO 17308:2015(E)BS ISO 17308:2015ISO 17308:2015(E)ii ISO 2015 All rights reservedCOPYRIGHT PROTECTED DOCUMENT ISO 2015All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form or by any means, electroni

6、c or mechanical, including photocopying, or posting on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below or ISOs member body in the country of the requester.ISO copyright officeCase postale 56 CH-1211 Geneva 20Tel. + 41 22

7、 749 01 11Fax + 41 22 749 09 47E-mail copyrightiso.orgWeb www.iso.orgPublished in SwitzerlandBS ISO 17308:2015ISO 17308:2015(E)Contents PageForeword ivIntroduction v1 Scope . 12 Normative references 13 Terms and definitions . 14 Reagents 15 Apparatus . 26 Sampling 27 Apparatus calibration . 27.1 Cle

8、aning of the sample vessel. 27.2 Cleaning of the measuring cell 37.3 Checking the cell constant . 37.3.1 Principle 37.3.2 Procedure . 38 Measurement procedure 38.1 Using thermostatic bath or thermostatic vessel 38.2 Using thermo compensation . 49 Expression of results 410 Repeatability, r . 411 Repr

9、oducibility, R 4Annex A (informative) Guidance on conductance and conductivity 5 ISO 2015 All rights reserved iiiBS ISO 17308:2015ISO 17308:2015(E)ForewordISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of

10、preparing International Standards is normally 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,

11、 in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.The procedures used to develop this document and those intended for its further maintenance are described in the ISO/

12、IEC Directives, Part 1. In particular the different approval criteria needed for the different types of ISO documents should be noted. This document was drafted in accordance with the editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).Attention is drawn to the possibility

13、 that some of the 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. Details of any patent rights identified during the development of the document will be in the Introduction and/or on the ISO list of paten

14、t declarations received (see www.iso.org/patents).Any trade name used in this document is information given for the convenience of users and does not constitute an endorsement.For an explanation on the meaning of ISO specific terms and expressions related to conformity assessment, as well as informa

15、tion about ISOs adherence to the WTO principles in the Technical Barriers to Trade (TBT), see the following URL: Foreword Supplementary information .The committee responsible for this document is ISO/TC 28, Petroleum products and lubricants, Subcommittee SC 7, Liquid biofuels.iv ISO 2015 All rights

16、reservedBS ISO 17308:2015ISO 17308:2015(E)IntroductionConductivity is related to the electrical current which is achieved by the ions displacement into solution in an electrical field.The importance of measuring conductivity is due to its role in corrosion processes which can harm metallic component

17、s and therefore cause bad engine functioning at long term.Ethanol can be contaminated with ion solutions in many ways, such as water contamination, chemical treatment in industrial processes, addition of chemical additives, incorrect transportation and storage, generally related to the cleanliness o

18、f tanks.The ascertainment of the conductivity is usually carried out through the measurement of the electrical conductance between two platinum electrodes, immersed in an electrolytic solution and connected to a source of alternating electromotive force of a typical frequency. The resulting current

19、is directly proportional to the number of ions present in the solution, mobility and ionic valence, and temperature.In the measuring of the conductance, it is essential to use an alternating current in order to eliminate the undesirable effects of faradaic currents. In the case of an alternating res

20、ultant current, an inversion of the polarization occurs every half cycle and, consequently, the inversion of the flow of the migration of the ions, leading to a non-faradaic process, which comprises the formation of a double electrical layer in the electrode-solution interface, called double electri

21、cal layer, with the potential decreasing linearly in the first part and exponentially in the second part.In an alternating fashion, the surfaces of the electrodes act as capacitors; the capacitive current increases with the frequency and the size of the electrodes. The control of these variables is

22、in order, so that the alternating current flows preferentially in the form of non-faradaic processes. With an alternating current, there is a reduction of the polarization effect and, as a consequence, an absence of faradaic currents.In this sense, platinization, that is, covering the surface of the

23、 electrodes with a layer of platinum black, increases its surface area significantly and, consequently, its capacitance which causes a reduction in the faradaic current. Further, as a result of the increase in capacitance, there is a reduction in the capacitive reactance, favouring the flow of curre

24、nt in the cell.For both a metallic or electrolytic conductors, the Ohm Law (E = IR) sets forth that the intensity of the current (I) which passes through an electrical conductor is inversely proportional to the resistance (R), where E represents the difference in potential and the inverse of the res

25、istance is the conductance (G = 1/R).Further information is provided in Annex A. ISO 2015 All rights reserved vBS ISO 17308:2015BS ISO 17308:2015Petroleum products and other liquids Ethanol Determination of electrical conductivityWARNING The use of this International Standard can involve hazardous m

26、aterials. This International Standard does not purport to address all the safety problems associated with its use. It is the responsibility of the user of this International Standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior

27、to use.1 ScopeThis International Standard specifies a test method for the determination of the electrical conductivity in ethanol fuel and mixtures (including E85) in the range of 0,5 Scm1to 4 Scm1at a temperature of 25 C. The electrical conductivity is determined from the measured electrical conduc

28、tance.2 Normative referencesThe following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any

29、amendments) applies.ISO 3170, Petroleum liquids Manual samplingISO 3171, Petroleum liquids Automatic pipeline sampling3 Terms and definitionsFor the purposes of this document, the following terms and definitions apply.3.1conductivityelectrical current which is achieved by the ions displacement into

30、the solution in an electrical fieldNote 1 to entry: The determination of the electrical conductivity is carried out by means of a direct conductivity meter (5.1) measurement, using a measuring cell (5.2) suitable for low conductivity measurements. The measurement is carried out at a sample temperatu

31、re of (25,0 0,1) C.4 Reagents4.1 Analytical grade anhydrous ethanol, for cleaning and rinsing the conductivity cell and the sample vessel before undertaking the measurements.4.2 KCl calibration solution, with 70 % de-ionized water and 30 % 1-propanol (99 %), approximately 5 Scm1, or certified refere

32、nce material approximately 5 Scm1.KCl solution with 70 % deionized water and 30 % 1-propanol 99 %, until 25 Scm1or less, Certified Reference Material until 25 Scm1or less, may also be used when it is not possible to carry out calibration using the above-mentioned solution.4.3 De-ionized or distilled

33、 water, with a maximum conductivity of 0,5 Scm1or less for cleaning and rinsing the sample vessel and the measuring cell.INTERNATIONAL STANDARD ISO 17308:2015(E) ISO 2015 All rights reserved 1BS ISO 17308:2015ISO 17308:2015(E)5 Apparatus5.1 Conductivity meter, which can be operated adequately with a

34、 0,1 cm1cell constant operating at a frequency of the alternating voltage between 50 Hz and 500 Hz directly to the measuring cell, with manual or automatic temperature correction and a resolution of 0,01 Scm1.5.2 Electrical conductivity cell, built with material which is inert to pure ethanol or fue

35、l ethanol (including E85). The cell shall be platinised or non-platinised with a constant of (0,1 0,02) cm1.5.3 Integrated thermo compensator with a conductivity cell, with a minimum resolution of 0,1 C.5.4 Thermostatic bath, or another system capable of maintaining the temperature at 25 C, with a m

36、inimum resolution of 0,1 C.5.5 Temperature sensor, with a minimum resolution of 0,1 C, preferably, integrated to the conductivity cell in order to provide to the system the minimal interferences. Temperatures near (25,0 0,1) C are supposed to be measured.5.6 Magnetic stirrer, which will be useful fo

37、r assuring temperature homogeneity in the sample. PTFE (polytetrafluoroethylenecoated) stirring magnet shall be used.5.7 Thermostable sample vessel, having a capacity of 20 ml to 500 ml or any proper container (glass, plastic, or stainless steel made), into which the sample to be measured is filled.

38、 The sample vessel shall be designed to ensure that the sample to be measured can be maintained at a temperature (25,0 0,1) C.6 Sampling6.1 Unless specified otherwise, samples shall be taken in accordance with ISO 3170 or ISO 3171 and/or the requirements of national standards regarding the sampling

39、of fuels.6.2 Only glass bottles shall be used for samples. Sampling should be carried out using ensured clean glass flasks in order to avoid any contamination. Rinse the flask with the product before sampling. Avoid a stopper made up of any materials that can react with, or contaminate samples.7 App

40、aratus calibration7.1 Cleaning of the sample vesselBefore the measurement, the sample vessel (5.7) is rinsed several times with ethanol (4.1). The rest of the ethanol used for rinsing shall be dripped off. If there are any visible contaminations (e.g. stains) on the inner glass surface of the sample

41、 vessel, the vessel shall not be used.2 ISO 2015 All rights reservedBS ISO 17308:2015ISO 17308:2015(E)7.2 Cleaning of the measuring cellThe measuring cell shall be cleaned thoroughly with water and rinsed with ethanol (4.1) or ethanol fuel before the measurement. If there are any visible contaminati

42、ons (e.g. stains) on the inner surface of the measuring cell, the cell shall not be used.NOTE Special care should be addressed if saline samples were in contact with the sample vessel or measurement cell. Rinse thoroughly with water, drying them afterwards. Finally, devices should be rinsed with eth

43、anol. Sample may be poured down directly from the sample container into the sample vessel. In case an intermediate vessel is required for transferring, concerns must be addressed to evaluate cleanliness of the intermediate vessel.7.3 Checking the cell constant7.3.1 PrincipleThe conductivity meters (

44、5.1) usually display in the checking procedure information about cell constant. This information is relevant due to electrodes surface area which is related to measurement accuracy.7.3.2 Procedure7.3.2.1 The procedure shall be as follows:a) insert in the conductivity meter (5.1) the value of electro

45、lytic conductivity according to calibration solution value (4.2), following meter manufacturers instructions;b) rinse the conductivity cell (5.2) using calibration solution (4.2);c) transfer the calibration solution (4.2) to a thermostatic vessel or any proper container (glass, plastic, or stainless

46、 steel made) in case of using a thermostatic bath (5.4). The transfer shall be carried out until covering measurement electrodes and temperature sensor (5.5);d) stir gently the sample, for at least 1 min, assuring temperature homogeneity;e) carry out measurement reading to (25,0 0,1) C. The cell con

47、stant shall be considered suitable when reading is between 0,08 cm1to 0,12 cm1;7.3.2.2 When the cell constant fails to meet the requirements, rinse the cell according to manufacturers instructions and repeat 7.3.2.1.8 Measurement procedure8.1 Using thermostatic bath or thermostatic vesselThe procedu

48、re shall be as follows:a) rinse cell with sample prior to determination;b) transfer a portion of the sample to the container in the thermostatic bath (5.4) or thermostatic vessel until covering measurement electrodes and temperature sensor assuring temperature at (25,0 0,1) C;c) stir the sample gent

49、ly for at least 1 min, assuring temperature homogeneity. Once a constant temperature of (25 0,1) C has been reached in the solution, stop stirring, and the measuring can be started. ISO 2015 All rights reserved 3BS ISO 17308:2015ISO 17308:2015(E)8.2 Using thermo compensationThe procedure shall be as follows:a) set the conductivity meter (5.1) to reference temperature (25 C) and adjust temperature correction coefficient to 2,2 %/C as indicated in Formula (1);b) rinse cell with