EN ISO 10101-3-1998 en Natural Gas - Determination of Water by the Karl Fischer Method - Part 3 Coulometric Procedure《天然气 卡尔·费休法测定天然气中的水 第3部分 电量滴定程序》.pdf

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1、BRITISH STANDARD BS EN ISO 10101-3:1998 BS 3156-11.3.3: 1994 Implementing Amendment No. 1 to BS3156-11.3.3:1994 ISO10101-3:1993 (renumbers the BS as BSENISO 10101-3:1998), not published separately Natural gases Determination of water by the Karl Fischer method Part 3: Coulometric procedure The Europ

2、ean Standard EN ISO 10101-3:1998 has the status of a British Standard ICS 75.060BSEN10101-3:1998 This British Standard, having been prepared under the directionof the Petroleum Standards Policy Committee, waspublished under the authorityof the Standards Boardand comes into effect on 15 March1994 BSI

3、 05-1999 The following BSI references relate to the work on this standard: Committee reference PTC/15 Draft for comment 92/52712 DC ISBN 0 580 22957 2 Committees responsible for this British Standard The preparation of this British Standard was entrusted by the Petroleum Standards Policy Committee (

4、PTC/-) to Technical Committee PTC/15 upon which the following bodies were represented: British Compressed Gases Association British Gas plc Department of Trade and Industry (Gas and Oil Measurement Branch) Department of Trade and Industry (National Engineering Laboratory) Institute of Petroleum Amen

5、dments issued since publication Amd. No. Date Comments 10053 July 1998 Implementation of EN ISO 10101-3:1998BSENISO10101-3:1998 BSI 05-1999 i Contents Page Committees responsible Inside front cover National foreword ii Foreword 2 1 Scope 3 2 Normative references 3 3 Principle 3 4 Reagents 3 5 Appara

6、tus 3 6 Sampling 3 7 Procedure 3 8 Expression of results 4 9 Test report 4 Annex ZA (normative) Normative references to international publications with their relevant European publications 8 Figure 1 Titration cell 5 Figure 2 Karl Fischer apparatus for coulometric determination Typical assembly 6 Fi

7、gure 3 Gas inlet with 3-way valve 6 Figure 4 Drying tube in the gas outlet line 7 Figure 5 Repeatability r and reproducibility R 7 List of references Inside back coverBSENISO10101-3:1998 ii BSI 05-1999 National foreword This British Standard has been prepared under the direction of the Petroleum Sta

8、ndards Policy Committee and is the English language version of ENISO10101-3:1998 Natural gas Determination of water by the Karl Fischer method Part3:Coulometric procedure published by the European Committee for Standardization (CEN). It is identical with ISO10101-3:1993 published by the Internationa

9、l Organization for Standardization (ISO). International Standard ISO10101-3 was prepared by Technical Committee ISO/TC193, Natural gas, Subcommittee SC1, Analysis of natural gas, in which the United Kingdom participated. ISO 10101 consists of the following Parts, under the general title Natural gas

10、Determination of water by the Karl Fischer method. Part 1: Introduction; Part 2: Titration procedure; Part 3: Coulometric procedure. The Technical Committee has reviewed the provisions of ISO5257:1986, to which normative reference is made in the text, and has decided that they are acceptable for use

11、 in conjunction with this standard. A British Standard 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 not of itself confer immunity from legal obligations. Cross

12、-references International standard Corresponding British Standard ISO 10101-1:1993 BS3156 Analysis of fuel gases Part 11 Methods for non-manufactured gases Section 11.3 Determination of water in natural gas by the Karl Fischer method Subsection 11.3.1:1994 Introduction (Identical) Summary of pages T

13、his document comprises a front cover, an inside front cover, pages i and ii, theENISO title page, pages 2 to 8, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on theins

14、ide front cover.EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN ISO 10101-3 March 1998 ICS 75.060 Descriptors: See ISO document English version Natural gas Determination of water by the Karl Fischer method Part3:Coulometric procedure (ISO 10101-3:1993) Gaz naturel Dosage de leau par la mthode d

15、e Karl Fischer Partie3:Mthode coulomtrique (ISO 10101-3:1993) Erdgas Bestimmung des Wassergehaltes nach Karl Fischer Teil3:Coulometrisches Verfahren (ISO 10101-3:1993) This European Standard was approved by CEN on 22 February 1998. CEN members are bound to comply with the CEN/CENELEC Internal Regula

16、tions 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 Central Secretariat or to any CEN member. This Eur

17、opean 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 Central Secretariat has the same status as the official versions. CEN members are the nat

18、ional standards bodies of Austria, Belgium, CzechRepublic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom. CEN European Committee for Standardization Comit Europen de Normalisation Europisch

19、es Komitee fr Normung Central Secretariat: rue de Stassart 36, B-1050 Brussels 1998 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members Ref. No. EN ISO 10101-3:1998 EENISO10101-3:1998 BSI 05-1999 2 Foreword The text of the International Standard fr

20、om Technical Committee ISO/TC193, Natural gas, of the International Organization for Standardization (ISO) has been taken over as a European Standard by CEN/CS. This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at t

21、he latest by September1998, and conflicting national standards shall be withdrawn at the latest by September1998. According to CEN/CENELEC Internal Regulations, the following countries are bound to implement this European Standard: Austria, Belgium, CzechRepublic, Denmark, Finland, France, Germany,

22、Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and the UnitedKingdom. Endorsement notice The text of the International Standard ISO10101-3:1993 has been approved by CEN as a European Standard without any modification. NOTENormative references t

23、o International Standards are listed in Annex ZA (normative).ISO10101-3:1993(E) BSI 05-1999 3 WARNING Local safety regulations must be taken into account, when the equipment is located in hazardous areas. Due to the toxicity and odour of pyridine, the user should ensure that there is adequate ventil

24、ation. 1 Scope This part of ISO10101 specifies a coulometric procedure for the direct determination of water content by the Karl Fischer method. The method applies to natural gas and other gases which do not react with Karl Fischer reagents. It applies to water concentrations between5mg/m 3and5000mg

25、/m 3 . Volumes are expressed a temperature of273,15K (0C) and a pressure of101,325kPa (1atm). 2 Normative references The following standards contain provisions which, through reference in this text, constitute provisions of this part of ISO10101. At the time of publication, the editions indicated we

26、re valid. All standards are subject to revision, and parties to agreements based on this part of ISO10101are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below. Members of IEC and ISO maintain registers of currently valid International Sta

27、ndards. ISO 5725:1986, Precision of test methods Determination of repeatability and reproducibility for a standard test method by inter-laboratory tests. ISO 10101-1:1993, Natural gas Determination of water by the Karl Fischer method Part1:Introduction. 3 Principle A measured volume of gas is passed

28、 through the titration cell, where the water is absorbed by the anodic solution. The iodine required for the determination of water by the Karl Fischer reaction is generated coulometrically from iodide. The quantity of electricity is directly proportional to the mass of iodine generated and hence to

29、 the mass of water determined. The principle and chemical reactions of the Karl Fischer method are given in ISO10101-1:1993, clauses3 and4; interferences are also described in clause4 of ISO10101-1. 4 Reagents 4.1 Reagents specially formulated for coulometric determination NOTE 1A typical compositio

30、n of the anodic solution is as follows:34% (m/m) trichloromethane, 3% (m/m) tetrachloromethane,22% (m/m) methanol, the remainder being sulfur dioxide and pyridine. Other reagents may be used, for the coulometric determination by the Karl Fischer method, if they have shown to be satisfactory. 4.2 Ref

31、erence solution, e.g.water and methanol mixture, with a water content of5,0mg/l 4% or10,0mg/l 4%. Keep this solution in a flask sealed with a septum. 4.3 Phosphorus pentoxide, with indicator. 5 Apparatus A diagram of the titration cell is shown in Figure 1 and a diagram of the complete apparatus is

32、shown in Figure 2. Figure 3 and Figure 4 illustrate the gas inlet with 3-way valve and the drying tube in the gas outlet line, respectively. All parts which come into contact with gas shall consist of glass and stainless steel. Flexible connections shall be polychloroprene or fluoroelastomers. The r

33、otor of the gas inlet tap shall be of polytetrafluoroethylene. 6 Sampling See ISO 10101-1:1993, clause 5. 7 Procedure 7.1 Installation Follow the manufacturers instructions for the addition of reagents to the cells, for switching on and for the determination of any initial water. 7.2 Testing the res

34、ponse Flush a104l syringe twice with reference solution(4.2) and introduce a measured amount (about104l) into the anodic cell with the tip of the needle below the surface of the liquid. Switch on the stirrer and start the determination. The results, expressed in micrograms, should agree with the mas

35、s of water introduced with the reference solution to within the expected repeatability. If sufficiently good agreement does not exist, look for a technical defect in the apparatus and resolve it before use.ISO10101-3:1993(E) 4 BSI 05-1999 7.3 Measurement Switch on the magnetic stirrer. Purge the sam

36、ple line to atmosphere through the 3-way valve. Adjust the 3-way valve to direct gases into the titration vessel and adjust the gas flow to between30l/h and40l/h. Measure the flow at the exit from the cell with a wet gas meter. The gas volume to be used depends upon the anticipated concentration of

37、water. When this volume has passed through the cell, return the 3-way valve to the former position. NOTE 2The optimum flowrate depends on the geometry of the equipment. A check that all the water is being absorbed should be carried out by passing the same volume of gas at different flowrates and ens

38、uring that equal results are obtained. For low water concentrations, it may be preferable to delay the determination until the required volume has been passed. The delayed determination procedure can only be applied if it is available as a programmable feature on the coulometer, which then continues

39、 to compensate for the background over the time entered into the memory, if this procedure is used, the operator should be satisfied that automatic compensation for zero drift is still correctly applied. The drift should be constant during the whole time of the determination. 7.4 Blank determination

40、 In the case of water concentrations (less than100mg/m 3 ), perform a blank determination to correct for losses of iodine by evaporation during passage of the gas sample. To this end, install an absorber packed with phosphorus pentaxide (4.3) as close as possible to the inlet of the titration cell.

41、Pass through an amount of dry gas, under the same conditions as those applied for the actual sample (flow, time, pressure and temperature). Repeat blank determinations until a constant level is achieved. NOTE 3The water vapour concentration at equilibrium with phosphorus pentoxide amounts to0,2mg/m

42、3 . Under ambient conditions, iodine losses by evaporation will be equivalent to water concentrations of1mg/m 3to4mg/m 3 . The contents of the absorber should be replaced when the coloured zone occupies more than50% of the absorber length. 8 Expression of results 8.1 Method of calculation Calculate

43、the water content A(H 2 O), expressed in milligrams per cubic meter at273,15K (0C) and101,325kPa (1atm), of the gas using the equation where If necessary, the water content can be corrected for interferences due to sulfur coumpounds as described in ISO 10101-1:1993, clause4. Express the water conten

44、t as A(H 2 O), in milligrams per cubic metre, choosing the number of significant figures according to the value of the repeatability. 8.2 Precision 8.2.1 Repeatability, r If one operator determines two different results under repeatable conditions, both results shall be considered as acceptable and

45、in accordance with this part of ISO10101, provided that they do not differ by more than the numerical value of r shown graphically in Figure 5, determined according to ISO5725. 8.2.2 Reproducibility, R If different laboratories determine results under comparable conditions, both results shall be con

46、sidered as acceptable and in accordance with this part of ISO10101, provided that they do not differ by more than the numerical value of R shown graphically in Figure 5, determined according to ISO5725. 9 Test report The test report shall contain at least the following information: a) a reference to

47、 this part of ISO10101; b) the date and time of sampling or measurement; c) the place of sampling or measurement; d) whether the analysis was performed on-site, or on a sample returned to the laboratory; e) the temperature and pressure of the gas stream at the time of sampling or analysis; f) the co

48、ncentration of, and correction for, any interfering substances in the gas; g) any deviation from the procedure specified. m 0 is the mass, in micrograms, of water obtained during the blank determination; m 1 is the mass, en micrograms, of water obtained during the sample determination; A is the temp

49、erature, in degrees Celsius, of the gas in the wet-test gas meter; V A is the volume, in litres, of gas passed through the cell; p A is the absolute pressure, in kilopascals, of the gas in the wet-test gas meter; p W is the vapour pressure, in kilopascals, of water at temperature A .ISO10101-3:1993(E) BSI 05-1999 5 Figure 1 Titration cellISO10101-3:1993(E) 6 BSI 05-1999 Figure 2 Karl Fischer apparatus for coulometric determination Typical assembly Figure 3 Gas inlet with 3-way valveISO10101-3:1993