1、BSI Standards PublicationBS ISO 17197:2014Dimethyl ether (DME) for fuels Determination of watercontent Karl Fischer titrationmethodBS ISO 17197:2014 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of ISO 17197:2014.The UK participation in its preparation was entrusted
2、 to TechnicalCommittee 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.
3、The British Standards Institution 2014. Published by BSI StandardsLimited 2014ISBN 978 0 580 79348 6ICS 71.080.60; 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 Comm
4、ittee on 31 December 2014.Amendments issued since publicationDate Text affectedBS ISO 17197:2014 ISO 2014Dimethyl ether (DME) for fuels Determination of water content Karl Fischer titration methodDimthylether (DME) pour carburants et combustibles Dtermination de la teneur en eau Mthode par titrage K
5、arl FischerINTERNATIONAL STANDARDISO17197First edition2014-11-15Reference numberISO 17197:2014(E)BS ISO 17197:2014ISO 17197:2014(E)ii ISO 2014 All rights reservedCOPYRIGHT PROTECTED DOCUMENT ISO 2014All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or uti
6、lized otherwise in any form or by any means, electronic 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 copyrig
7、ht officeCase postale 56 CH-1211 Geneva 20Tel. + 41 22 749 01 11Fax + 41 22 749 09 47E-mail copyrightiso.orgWeb www.iso.orgPublished in SwitzerlandBS ISO 17197:2014ISO 17197:2014(E)Contents PageForeword ivIntroduction v1 Scope . 12 Normative references 13 Principle 14 Reagents and materials . 15 App
8、aratus . 26 Sampling and sample handling . 37 Preparation of apparatus 38 Calibration and standardization 39 Procedure. 410 Calculation 511 Report 612 Precision . 6Annex A (informative) Report of the interlaboratory tests 8Bibliography .10 ISO 2014 All rights reserved iiiBS ISO 17197:2014ISO 17197:2
9、014(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 carried out through ISO technical committees. Each member body interested in a subject for whic
10、h 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 work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all ma
11、tters of electrotechnical standardization.The procedures used to develop this document and those intended for its further maintenance are described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the different types of ISO documents should be noted. This d
12、ocument 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 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
13、 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 patent declarations received (see www.iso.org/patents).Any trade name used in this document is information given for the convenience of users and
14、does not constitute an endorsement.For an explanation on the meaning of ISO specific terms and expressions related to conformity assessment, as well as information about ISOs adherence to the WTO principles in the Technical Barriers to Trade (TBT), see the following URL: Foreword Supplementary infor
15、mation .The committee responsible for this document is ISO/TC 28, Petroleum products and lubricants, Subcommittee SC 4, Classifications and specifications.iv ISO 2014 All rights reservedBS ISO 17197:2014ISO 17197:2014(E)IntroductionIn general, large amounts of DME in international trade and domestic
16、 transportation can be executed using sea and/or various land transportations. Throughout loading and transportation, there is a risk of increasing the DMEs water content.DME is soluble in water and the amount of water contained in the DME gives significant detrimental influence when it is used as f
17、uel.Accordingly, water content in DME has to be analysed accurately using recognized procedures by the parties concerned.In this International Standard, one of the most common practices to be applied to analysis of water content is standardized. ISO 2014 All rights reserved vBS ISO 17197:2014BS ISO
18、17197:2014Dimethyl ether (DME) for fuels Determination of water content Karl Fischer titration methodWARNING The use of this International Standard may involve hazardous materials, operations, and equipment. This International Standard does not purport to address all of the safety problems associate
19、d 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 to use.1 ScopeThis International Standard specifies a procedure of test for the amount of water con
20、tent in DME used as fuel by the Karl Fischer titration method. This procedure is applicable to determine the amount of water up to the value specified in ISO 16861.This test method is intended for use with commercially available coulometric (or volumetric) Karl Fischer reagents and for the determina
21、tion of water in DME additives, lube oils, base oils, automatic transmission fluids, hydrocarbon solvents, and other petroleum products. By proper choice of the sample size, this test method can be used to determine water from mg/kg (ppm) to percent level concentrations.NOTE The precision of this me
22、thod has been studied for a limited set of samples and content levels by a limited amount of labs. It allows establishment of a quality specification of DME but cannot be considered as a full precision determination in line with the usual statistical methodology as in ISO 4259.2 Normative references
23、The 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 amendments) applies.ISO 2994
24、5, Refrigerated non-petroleum-based liquefied gaseous fuels Dimethylether (DME) Method of manual sampling onshore terminals3 PrincipleA gaseous sample of DME is bubbled into the titration vessel of a coulometric (or volumetric) Karl Fischer apparatus. The titration is then performed until all of the
25、 water has been titrated, the end point is detected by an electrometric end point detector, and the titration is terminated. Based on the stoichiometry of the reaction, 1,0 mol of iodine reacts with 1,0 mol of water; thus, the quantity of water is proportional to the quantity of Karl Fisher reagent
26、used.4 Reagents and materials4.1 Sample solvent, reagent grade.Use methanol (anhydrous) with minimum purity 99,9 mass % and maximum water content 0,1 mass % (and preferably less than 0,05 mass %).This water content could be achieved by dissolving 24 g of magnesium metal turnings in 200 ml of methano
27、l (the reaction could be vigorous). When the reaction is completed, add 3 l of methanol. Reflux for 5 h. Distill directly into the container in which the 99,9 mass % methanol is to be kept. Vent the system through a drying tube during the distillation.INTERNATIONAL STANDARD ISO 17197:2014(E) ISO 201
28、4 All rights reserved 1BS ISO 17197:2014ISO 17197:2014(E)4.2 Coulometric Karl Fischer reagent.Use standard, commercially available reagents for coulometric Karl Fischer titrations.4.2.1 Anode solution.Use a standard, commercially available anode Karl Fischer solution. A newly made solution should be
29、 used.4.2.2 Cathode solution.Use a standard, commercially available cathode Karl Fischer solution. A newly made solution should be used.4.3 Volumetric Karl Fischer reagent.Use standard, commercially available, pyridine-free Karl Fischer reagents for volumetric titrations (one or two components). Use
30、 as described in 4.1.4.3.1 One component.Use a commercial volumetric Karl Fischer reagent. Fresh Karl Fischer reagent shall be used (alternatively, the solution should be standardized or calibrated each time it is used).4.3.2 Two components.Use commercial volumetric Karl Fischer reagent. Mix the two
31、 reagents (part 1 and part 2) just before using. The solution should be standardized and calibrated as soon as possible.4.3.3 Methanol (anhydrous).4.4 Molecular sieve.A ball- or cylindrical-shaped molecular sieve shall be used. All vented ends of the system shall be through drying tubes filled with
32、this molecular sieve. Alternatively, anhydrous calcium chloride could be used.4.5 Water.Distilled water or water of equivalent purity shall be used.5 Apparatus5.1 Karl Fischer apparatus (coulometric or volumetric), using electrometric end point.A number of automatic coulometric and volumetric Karl F
33、ischer titration assemblies consisting of titration cell, platinum electrodes, magnetic stirrer, and a control unit are available on the market. Instructions for operation of these devices are provided by the manufacturers and are not described herein. A sample is introduced using a stainless steel
34、needle for gas bubbling; the length can be about 200 mm and the diameter can be about 1 mm.5.2 Pressure gas cylinder.Samples are most easily added to the titration vessel by means of double-valve pressurized gas cylinders (size is up to 100 ml, tested pressure not less than 3,0 MPa) that the mass co
35、uld be measurable. The sample should be delivered from the bottom of the cylinder.2 ISO 2014 All rights reservedBS ISO 17197:2014ISO 17197:2014(E)5.3 Electronic balance.The mass of the samples are determined by means of a top loading electronic balance with an accuracy of at least 1,0 mg and with ca
36、pacity that covers the mass of double-valve pressurized gas cylinders filled with the sample. The sample mass is concluded by the difference between the cylinder mass before and after the test (after excluding the purge sample quantity).6 Sampling and sample handling6.1 Samples shall be taken as des
37、cribed in ISO 29945.6.2 Test Specimen: the aliquot obtained from the laboratory sample for analysis by this test method. Once drawn, use the entire portion of the test specimen in the analysis.6.3 Select a test specimen size from 10 g to 20 g.7 Preparation of apparatus7.1 Follow the manufacturers di
38、rections for preparation and operation of the titration apparatus.7.2 Seal all joints and connections to the vessel to prevent atmospheric moisture from entering the apparatus.7.3 Add the sample solvent into the titration vessel to the level that is recommended by the manufacturer. Prepare the Karl
39、Fischer reagent as described in 4.2 or 4.3.For coulometric titration, add the Karl Fischer anode solution to the anode (outer) compartment. Add the solution to the level recommended by the manufacturer. Add the Karl Fischer cathode solution to the cathode (inner) compartment. Add the solution to a l
40、evel 2 mm to 3 mm below the level of the solution in the anode compartment.7.4 Turn on the apparatus and start the magnetic stirrer for a smooth stirring action. Allow the residual moisture in the titration vessel to be titrated until the end point is reached. Do not proceed beyond this stage until
41、the background current (or background titration rate) is constant and less than the maximum recommended by the manufacturer of the instrument.7.5 Install the needle to the double-valve gas cylinder. Stick the needle of the cylinder to the titration flask and fix the cylinder. The needle shall be rol
42、led with tissue paper or threaded into a silicone rubber plate to prevent dew condensation water from mixing into the titration flask.7.6 Open the liquid valve of the sample cylinder slowly and adjust the gas flow rate in the range of 0,5 g/min to 2,0 g/min. Be sure that the gas doesnt generate foam
43、 or overflow. The needle shall be below the liquid surface, with at least 3,0 cm to allow the water content in the bubbled gas to be extracted in the solvent.7.7 Allow the residual moisture in the titration vessel to be titrated until the end point is reached again. The system now is ready for sampl
44、e titration. Disconnect the sample cylinder and measure the mass and record as the “initial sample mass”.8 Calibration and standardization8.1 Standardize the Karl Fischer reagent at least once daily. ISO 2014 All rights reserved 3BS ISO 17197:2014ISO 17197:2014(E)8.2 Add enough solvent to the clean,
45、 dry titration vessel to cover the electrodes. The volume of solvent depends on the size of the titration vessel. Seal all openings to the vessel and start the magnetic stirrer for a smooth stirring action. Turn on the indicating circuit and adjust the instrument to give a reference end point.8.3 Fo
46、r the coulometric technique, follow the manufacturer instructions for instrument calibration.8.4 For the volumetric technique, standardize the Karl Fischer reagent with water by one of the following methods. From a water-filled pipette or syringe previously measured with mass to the nearest 0,1 mg,
47、add 1 drop of water (about 20 mg) to the sample solvent at end-point conditions and measure the mass of the syringe. Record the mass of the water added. Titrate the water with Karl Fischer reagent added from the pipette or syringe until a steady end point is reached for at least 30 s. Record to the
48、nearest 0,01 ml the volume of the Karl Fischer reagent needed to reach the end point. Fill a 10 l syringe with water taking care to eliminate air bubbles, wipe the needle with tissue paper to remove any residual water from the needle, and accurately determine the mass of syringe plus water to 0,1 mg
49、. Add the contents of the syringe to the sample solvent in the cell which has been adjusted to the end point ensuring that the tip of the needle is below the surface of the sample solvent. Reseal the vessel immediately. Remove any solvent from the needle by wiping it with tissue paper and measure the mass of the syringe to 0,1 mg. Titrate the water with Karl Fischer reagent as in 4.2 or 4.3.8.5 Calculate the water equivalence of the Karl Fischer reagent using Formula (1).F = W/T (1)whereF is the water equivalence of the Karl Fisch
