1、DEUTSCHE NORM September 200051869Document comprises 4 pages. No part of this translation may be reproduced without the prior permission ofDIN Deutsches Institut fr Normung e.V., Berlin. Beuth Verlag GmbH, 10772 Berlin, Germany,has the exclusive right of sale for German Standards (DIN-Normen).Determi
2、ning the water content of gaseous fuels andother gases by the Karl Fischer coulometric methodTranslation by DIN-Sprachendienst.In case of doubt, the German-language original should be consulted as the authoritative text.ICS 75.160.30Prfung von gasfrmigen Brennstoffen und sonstigen Gasen Bestimmung d
3、es Wassergehaltes nach Karl Fischer Coulometrisches VerfahrenIn keeping with current practice in standards published by the International Organization for Standardization(ISO), a comma has been used throughout as the decimal marker.ForewordThis standard has been prepared by Technical Committee Anfor
4、derungen an und Prfung von Brenngasenof the Fachausschuss Minerall- und Brennstoffnormung of the Normenausschuss Materialprfung (Mate-rials Testing Standards Committee).It is important to know the water content of gases for the following reasons:a) If the water precipitated is below the dew point of
5、 water vapour, it may combine with other constitu-ents and cause corrosion.b) Water collecting in the deeper sections of gas pipework is likely to result in failure of the system dueto mechanical damage. This would be caused by water hammer, generated when the gas is suddenly setin motion.c) The for
6、mation of hydrocarbon hydrates in high-pressure gas mains may cause the flow rate to bereduced or clogging of the pipework to occur.AmendmentsThis standard differs from the May 1986 edition in that the specifications from DIN EN ISO 10101-1 andDIN EN ISO 10101-3 have been deleted and replaced by a r
7、eference, and that it has been editorially revised.Previous editionDIN 51869: 1986-05.This standard, together withDIN EN ISO 10101-1 andDIN EN ISO 10101-3, July1998 editions, supersedesDIN 51869, May 1986 edition.English price group 5www.din.dewww.beuth.de06.04 9560307Page 2DIN 51869 : 2000-091 Scop
8、eThe method specified in this standard serves to determine the water content of gaseous fuels and other gasesto DIN 1340 which do not react with Karl Fischer reagents. For the analysis of natural gas, reference is madeto DIN EN ISO 10101-1 and DIN EN ISO 10101-3.Determination of the water content by
9、 the Karl Fischer coulometric method is independent of the quantity ofwater contained in a gas sample, provided that the dew point of water vapour is at least 5 C below the testtemperature.In the cases where the dew point of water vapour cannot be determined by the cooled mirror method specifiedin D
10、IN 51871 (e.g. as a result of condensation of other gas constituents above the dew point of water vapour),this standard may be used to estimate the dew point of water vapour on the basis of the water content.2 Normative referencesThis standard incorporates, by dated or undated reference, provisions
11、from other publications. These norma-tive references are cited at the appropriate places in the text, and the titles of the publications are listed below.For dated references, subsequent amendments to or revisions of any of these publications apply to thisstandard only when incorporated in it by ame
12、ndment or revision. For undated references, the latest edition ofthe publication referred to applies.DIN 1333 Presentation of numerical dataDIN 1340 Gaseous fuels and other gases Types, components and useDIN 12775 Laboratory thermometers with 0,1 C, 0,2 C and 0,5 C scale intervalsDIN 51851 Determini
13、ng the reduced gas volume of gaseous fuels and other gasesDIN 51853 Sampling of gaseous fuelsDIN 51871 Determining the dew point of water vapour of gaseous fuels and other technical gasesusing the cooled mirror methodDIN EN ISO 10101-1 Natural gas Determination of water by the Karl Fischer method Pa
14、rt 1: Introduction(ISO 10101-1 : 1993)DIN EN ISO 10101-3 Natural gas Determination of water by the Karl Fischer method Part 3: Coulometricprocedure (ISO 10101-3 : 1993)ISO 5725-1 : 1994 Accuracy (trueness and precision) of measurement methods and results Part 1: Gen-eral principles and definitions3
15、PrincipleA measured volume of gas is passed through a titration vessel, where the water is absorbed by an anodicsolution. The iodine required for the determination of water by the Karl Fischer reaction is generatedcoulometrically from the iodide present. The quantity of electricity is directly propo
16、rtional to the mass of iodinegenerated and hence to the mass of water to be determined.See DIN EN ISO 10101-1 for further information regarding the principle and chemical reactions.4 DesignationDesignation of the coulometric method of determining the water content by the Karl Fischer method (A) inac
17、cordance with this standard:Method DIN 51869-A5 ApparatusIn addition to the equipment specified in DIN EN ISO 10101-3, the following shall be used.5.1 Gas meter, wet type, with accessories (pressure gauge, DIN 12775 E 0,1/0/50 thermometer).5.2 Graduated syringe, of capacity 100 l.6 ReagentsThe follo
18、wing reagents shall be used.6.1 Cathodic solution, ready-to-use.6.2 Anodic solution, ready-to-use alcoholic solution containing pyridine or other nitrogeneous compounds.6.3 Reference solution (e.g. a water and methanol mixture, with a water content of (5 t 0,2) mg/l).Page 3DIN 51869 : 2000-097 Sampl
19、ingSampling shall be carried out as specified in DIN 51853. Reference is made to DIN EN ISO 10101-1 for furtherdetails.8 ProcedureThe procedure clause describes only essential steps of the procedure. For further information, reference ismade to the operating instructions supplied with the equipment
20、used.8.1 Starting the apparatusIntroduce into a titration vessel and a cathodic cell the quantity of anodic or cathodic solution recommendedby the manufacturer of the equipment. Start the magnetic stirrer. After stirring for a short time, the waterintroduced into the titration vessel is converted by
21、 the iodine generated coulometrically. The equilibriumbetween iodine and iodide is indicated optically and acoustically. The titrated, and thus anhydrous, anodicsolution is to be used as a solvent for the subsequent analysis.The speed of the stirrer shall be kept constant during the analyses.8.2 Tes
22、ting the responseUsing a syringe, introduce 100 l of reference solution through the septum into the titration vessel, with the tipof the needle slightly above the surface of the liquid and in contact with the sheath of the electrode.After removing the syringe and stirring for a short time, start the
23、 analysis. The result should agree with the massof water introduced with the reference solution to within the expected repeatability. In the case of substantialdeviations, look for a technical defect in the equipment and remedy it using the checklist of the manufacturersoperating instructions.8.3 Bl
24、ank testCarry out a blank test as specified in DIN EN ISO 10101-3.9 EvaluationCalculate the water content, b(H2O), in mg/m3, using the following equation:b(H2O) = (G)OH2Vm )(wherem(H2O) is the mass of water obtained, in g;V(G) is the reduced gas volume as in DIN 51851, in l.NOTE: 1 g/l corresponds t
25、o 1 mg/m3.10 Expression of resultRefer to this standard and report the water content, b(H2O), in mg/m3, choosing the number of significant placesto suit the repeatability limit (see clause 11).DIN 1333 shall be taken into account, when rounding to the last significant place.11 Precision(cf. ISO 5725
26、-1).Repeatability limit(same operator, same equipment)If two results are obtained under repeatability conditions, they shall be considered acceptable and in conformitywith this standard if they differ by no more than the value to be read from the graph in figure 1.Reproducibility limit(different ope
27、rators, different equipment)If two laboratories each obtain a result under reproducibility conditions, both results shall be consideredacceptable and in conformity with this standard if they differ by no more than the value to be read from the graphin figure 1.Page 4DIN 51869 : 2000-0912 Test report
28、As specified in DIN EN ISO 10101-3.Figure 1: Repeatability and reproducibility limits, r and RBibliographyDIN EN ISO 10101-2 Natural gas Determination of water by the Karl Fischer method Part 2: Titrationprocedure (ISO 10101-2 : 1993)ISO 10715 : 1997 Natural gas Sampling guidelinesFischer, K. Neues
29、Verfahren zur maanalytischen Bestimmung des Wassergehaltes von Flssigkeiten und festenKrpern (New method of determining the water content of liquid and solid materials by titrimetric analysis).Z. Angew. Chemie, 1935: 48, 394.Eberius, E. Wasserbestimmung mit Karl-Fischer-Lsung (Determination of water
30、 using the Karl-Fischer rea-gent). Weinheim/Bergstrae: Verlag Chemie GmbH, 1958.Kaesler, H. Direkte Bestimmung des Wassergehaltes in Gasen nach Karl Fischer (Direct determination of waterin gases using the Karl Fischer method). gwf gas/erdgas, 1985: 125 (3), 125131.Scholz, E. Karl-Fischer-Titration, Methoden zur Wasserbestimmung (Karl Fischer titration Methods of wateranalysis). Berlin/Heidelberg/New York/Tokyo: Springer-Verlag, 1984.
