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1、BRITISH STANDARD BS EN ISO 10101-3:1998 BS 3156-11.3.3: 1994 Implementing Amendment No. 1 to BS 3156-11.3.3:1994 ISO 10101-3:1993 (renumbers the BS as BS EN ISO 10101-3:1998), not published separately Natural gases Determination of water by the Karl Fischer method Part 3: Coulometric procedure The E
2、uropean Standard EN ISO 10101-3:1998 has the status of a British Standard ICS 75.060 Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 19 15:35:31 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS EN 10101-3:1998 This British Standard, having been prepared under the direction of the Petroleum Standard
3、s Policy Committee, was published under the authority of the Standards Board and comes into effect on 15 March 1994 BSI 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 thi
4、s British Standard The preparation of this British Standard was entrusted by the Petroleum Standards Policy Committee (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
5、 Oil Measurement Branch) Department of Trade and Industry (National Engineering Laboratory) Institute of Petroleum Amendments issued since publication Amd. No.DateComments 10053July 1998Implementation of EN ISO 10101-3:1998 Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 19 15:35:31 GMT+00:00 20
6、06, Uncontrolled Copy, (c) BSI BS EN ISO 10101-3:1998 BSI 05-1999i Contents Page Committees responsibleInside front cover National forewordii Foreword2 1Scope3 2Normative references3 3Principle3 4Reagents3 5Apparatus3 6Sampling3 7Procedure3 8Expression of results4 9Test report4 Annex ZA (normative)
7、Normative references to international publications with their relevant European publications8 Figure 1 Titration cell5 Figure 2 Karl Fischer apparatus for coulometric determination Typical assembly6 Figure 3 Gas inlet with 3-way valve6 Figure 4 Drying tube in the gas outlet line7 Figure 5 Repeatabil
8、ity r and reproducibility R7 List of referencesInside back cover Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 19 15:35:31 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS EN ISO 10101-3:1998 ii BSI 05-1999 National foreword This British Standard has been prepared under the direction of the Petro
9、leum Standards Policy Committee and is the English language version of EN ISO 10101-3:1998 Natural gas Determination of water by the Karl Fischer method Part 3: Coulometric procedure published by the European Committee for Standardization (CEN). It is identical with ISO 10101-3:1993 published by the
10、 International Organization for Standardization (ISO). International Standard ISO 10101-3 was prepared by Technical Committee ISO/TC 193, Natural gas, Subcommittee SC 1, Analysis of natural gas, in which the United Kingdom participated. ISO 10101 consists of the following Parts, under the general ti
11、tle Natural gas 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 ISO 5257:1986, to which normative reference is made in the text, and has decided that they are a
12、cceptable for use 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 o
13、bligations. Cross-references International standardCorresponding British Standard ISO 10101-1:1993BS 3156 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) Su
14、mmary of pages This document comprises a front cover, an inside front cover, pages i and ii, the EN ISO 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 amendme
15、nt table on the inside front cover. Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 19 15:35:31 GMT+00:00 2006, Uncontrolled Copy, (c) BSI EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN ISO 10101-3 March 1998 ICS 75.060 Descriptors: See ISO document English version Natural gas Determinatio
16、n of water by the Karl Fischer method Part 3: Coulometric procedure (ISO 10101-3:1993) Gaz naturel Dosage de leau par la mthode de Karl Fischer Partie 3: Mthode coulomtrique (ISO 10101-3:1993) Erdgas Bestimmung des Wassergehaltes nach Karl Fischer Teil 3: Coulometrisches Verfahren (ISO 10101-3:1993)
17、 This European Standard was approved by CEN on 22 February 1998. 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 r
18、eferences concerning such national standards may be obtained on application to the Central Secretariat 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 membe
19、r into its own language and notified to the Central Secretariat has the same status as the official versions. CEN members are the national standards bodies of Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portug
20、al, Spain, Sweden, Switzerland and United Kingdom. CEN European Committee for Standardization Comit Europen de Normalisation Europisches 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
21、 CEN national Members Ref. No. EN ISO 10101-3:1998 E Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 19 15:35:31 GMT+00:00 2006, Uncontrolled Copy, (c) BSI EN ISO 10101-3:1998 BSI 05-1999 2 Foreword The text of the International Standard from Technical Committee ISO/TC 193, Natural gas, of the I
22、nternational 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 the latest by September 1998, and conflicting national s
23、tandards shall be withdrawn at the latest by September 1998. According to CEN/CENELEC Internal Regulations, the following countries are bound to implement this European Standard: Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherl
24、ands, Norway, Portugal, Spain, Sweden, Switzerland and the United Kingdom. Endorsement notice The text of the International Standard ISO 10101-3:1993 has been approved by CEN as a European Standard without any modification. NOTENormative references to International Standards are listed in Annex ZA (
25、normative). Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 19 15:35:31 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ISO 10101-3:1993(E) BSI 05-19993 WARNING Local safety regulations must be taken into account, when the equipment is located in hazardous areas. Due to the toxicity and odour of pyri
26、dine, the user should ensure that there is adequate ventilation. 1 Scope This part of ISO 10101 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.
27、 It applies to water concentrations between 5 mg/m3 and 5 000 mg/m3. Volumes are expressed a temperature of 273,15 K (0 C) and a pressure of 101,325 kPa (1 atm). 2 Normative references The following standards contain provisions which, through reference in this text, constitute provisions of this par
28、t of ISO 10101. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this part of ISO 10101 are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below. Members
29、 of IEC and ISO maintain registers of currently valid International Standards. 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 me
30、thod Part 1: Introduction. 3 Principle A measured volume of gas is passed 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 electric
31、ity is directly proportional to the mass of iodine generated and hence to the mass of water determined. The principle and chemical reactions of the Karl Fischer method are given in ISO 10101-1:1993, clauses 3 and 4; interferences are also described in clause 4 of ISO 10101-1. 4 Reagents 4.1 Reagents
32、 specially formulated for coulometric determination NOTE 1A typical composition 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 deter
33、mination by the Karl Fischer method, if they have shown to be satisfactory. 4.2 Reference solution, e.g. water and methanol mixture, with a water content of 5,0 mg/l 4 % or 10,0 mg/l 4 %. Keep this solution in a flask sealed with a septum. 4.3 Phosphorus pentoxide, with indicator. 5 Apparatus A diag
34、ram of the titration cell is shown in Figure 1 and a diagram of the complete apparatus is 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
35、 stainless steel. Flexible connections shall be polychloroprene or fluoroelastomers. The rotor 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 c
36、ells, for switching on and for the determination of any initial water. 7.2 Testing the response Flush a 10 4l syringe twice with reference solution (4.2) and introduce a measured amount (about 10 4l) into the anodic cell with the tip of the needle below the surface of the liquid. Switch on the stirr
37、er and start the determination. The results, expressed in micrograms, should agree with the mass 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
38、. Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 19 15:35:31 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ISO 10101-3:1993(E) 4 BSI 05-1999 7.3 Measurement Switch on the magnetic stirrer. Purge the sample line to atmosphere through the 3-way valve. Adjust the 3-way valve to direct gases into the
39、titration vessel and adjust the gas flow to between 30 l/h and 40 l/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 water. When this volume has passed through the cell, return the 3-way valve to the former po
40、sition. 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 ensuring that equal results are obtained. For low water concentrations, it may be preferable to
41、 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 to compensate for the background over the time entered into the memory, if this procedure i
42、s 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 In the case of water concentrations (less than 100 mg/m3), perform a blank determination to
43、 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. Pass through an amount of dry gas, under the same conditions as those applied for the actual
44、 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 to 0,2 mg/m3. Under ambient conditions, iodine losses by evaporation will be equivalent to water conce
45、ntrations of 1 mg/m3 to 4 mg/m3. The contents of the absorber should be replaced when the coloured zone occupies more than 50 % of the absorber length. 8 Expression of results 8.1 Method of calculation Calculate the water content A(H2O), expressed in milligrams per cubic meter at 273,15 K (0 C) and
46、101,325 kPa (1 atm), 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, clause 4. Express the water content as A(H2O), in milligrams per cubic metre, choosing the number of significant figu
47、res 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 in accordance with this part of ISO 10101, provided that they do not differ by more t
48、han the numerical value of r shown graphically in Figure 5, determined according to ISO 5725. 8.2.2 Reproducibility, R If different laboratories determine results under comparable conditions, both results shall be considered as acceptable and in accordance with this part of ISO 10101, provided that
49、they do not differ by more than the numerical value of R shown graphically in Figure 5, determined according to ISO 5725. 9 Test report The test report shall contain at least the following information: a) a reference to this part of ISO 10101; 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) th
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