1、November 2012 Translation by DIN-Sprachendienst.English price group 12No part of this translation may be reproduced without 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).I
2、CS 75.060!$QK“1924640www.din.deDDIN EN ISO 6974-2Natural gas Determination of composition and associated uncertainty by gaschromatography Part 2: Uncertainty calculations (ISO 6974-2:2012);English version EN ISO 6974-2:2012,English translation of DIN EN ISO 6974-2:2012-11Erdgas Bestimmung der Zusamm
3、ensetzung und der zugehrigen Unsicherheit durchGaschromatographie Teil 2: Unsicherheitsberechnungen (ISO 6974-2:2012);Englische Fassung EN ISO 6974-2:2012,Englische bersetzung von DIN EN ISO 6974-2:2012-11Gaz naturel Dtermination de la composition et de lincertitude associe par chromatographie enpha
4、se gazeuse Partie 2: Calculs dincertitude (ISO 6974-2:2012);Version anglaise EN ISO 6974-2:2012,Traduction anglaise de DIN EN ISO 6974-2:2012-11Together with DIN EN ISO6974-1:2012-11,supersedesDIN EN ISO 6974-2:2002-07 andDIN EN ISO 6974-1:2002-06www.beuth.deDocument comprises 24 pagesIn case of dou
5、bt, the German-language original shall be considered authoritative.11.12 DIN EN ISO 6974-2:2012-11 2 A comma is used as the decimal marker. National foreword This standard has been prepared by Technical Committee ISO/TC 193 “Natural gas”, Subcommittee SC 1 “Analysis of natural gas” (Secretariat: NEN
6、, Netherlands). The responsible German body involved in its preparation was the Normenausschuss Materialprfung (Materials Testing Standards Committee), Working Committee NA 062-05-73 AA Gasanalyse und Gasbeschaffenheit. DIN EN ISO 6974 consists of the following parts, under the general title Natural
7、 gas Determination of composition and associated uncertainty by gas chromatography: Part 1: General guidelines and calculation of composition Part 2: Uncertainty calculations Part 3: Determination of hydrogen, helium, oxygen, nitrogen, carbon dioxide and hydrocarbons up to C8using two packed columns
8、 Part 4: Determination of nitrogen, carbon dioxide and C1to C5and C6+hydrocarbons for a laboratory and on-line measuring system using two columns Part 5: Determination of nitrogen, carbon dioxide and C1to C5and C6+hydrocarbons for a laboratory and on-line process application using three columns Part
9、 6: Determination of hydrogen, helium, oxygen, nitrogen, carbon dioxide and C1to C8hydrocarbons using three capillary columns Part 7: Extended analysis Gas-chromatographic method (Revision of ISO 6975) (in preparation) Part 8: Micro-gas-chromatographic method (in preparation) In the German version,
10、the term Gebrauchsnormal (working measurement standard) is abbreviated in the text as GN (in accordance with the “Guide to the expression of uncertainty in measurement”, GUM), whereas in Subclause 6.7.1, the abbreviation “wms” is used as derived from the English term. The DIN Standard corresponding
11、to the International Standard referred to in this document is as follows: ISO 6974-1 DIN EN ISO 6974-1 Amendments This standard differs from DIN EN ISO 6974-1:2002-06 and DIN EN ISO 6974-2:2002-07 as follows: a) the title of the standard has been changed; b) both standards have been technically revi
12、sed: Part 1 gives guidelines for the quantitative analysis of natural gas and specifies data processing requirements for the determination of component mole fractions and Part 2 describes the calculation of the uncertainty of each component mole fraction. Previous editions DIN EN ISO 6974-1: 2002-06
13、 DIN EN ISO 6974-2: 2002-07 DIN EN ISO 6974-2:2012-11 3 National Annex NA (informative) Bibliography DIN EN ISO 6974-1, Natural gas Determination of composition and associated uncertainty by gas chromatography Part 1: General guidelines and calculation of composition DIN EN ISO 6974-2:2012-11 4 This
14、 page is intentionally blank EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN ISO 6974-2 May 2012 ICS 75.060 Supersedes EN ISO 6974-2:2002English Version Natural gas - Determination of composition and associated uncertainty by gas chromatography - Part 2: Uncertainty calculations (ISO 6974-2:201
15、2) Gaz naturel - Dtermination de la composition et de lincertitude associe par chromatographie en phase gazeuse - Partie 2: Calculs dincertitude (ISO 6974-2:2012)Erdgas - Bestimmung der Zusammensetzung und der zugehrigen Unsicherheit durch Gaschromatographie - Teil 2: Unsicherheitsberechnungen (ISO
16、6974-2:2012) This European Standard was approved by CEN on 14 May 2012. 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 bibliograp
17、hical references concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre 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 responsibili
18、ty of a CEN member into its own language and notified to the CEN-CENELEC Management Centre has the same status as the official versions. CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, H
19、ungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG Manag
20、ement Centre: Avenue Marnix 17, B-1000 Brussels 2012 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN ISO 6974-2:2012: EContents PageForeword .Introduction 1 Scope 2 Normative references .3 Terms and definitions .4 Symbols .4.1 Symb
21、ols .4.2 Subscripts .5 Calculation of uncertainty .5.1 General considerations .5.2 Principles .5.3 Step 9 Calculation of uncertainty of mole fractions .5.4 Step 10 Calculation of the expanded uncertainty of mole fractions 15Annex A (informative) Calculation of processed component uncertainties for t
22、he methane-by-difference approach .16Annex B (normative) Uncertainties of relative response factors 17Annex C (informative) Alternative calculation of the uncertainty of the value of the unknown 18Bibliography .EN ISO 6974-2:2012 (E) DIN EN ISO 6974-2:2012-11 245555556669920Foreword This document (E
23、N ISO 6974-2:2012) has been prepared by Technical Committee ISO/TC 193 “Natural gas“. 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 November 2012, and conflicting national standards shall be wit
24、hdrawn at the latest by November 2012. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN and/or CENELEC shall not be held responsible for identifying any or all such patent rights. This document supersedes EN ISO 6974-2:2002. Ac
25、cording to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland,
26、Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom. Endorsement notice The text of ISO 6974-2:2012 has been approved by CEN as a EN ISO 6974-2:2012 without any modification. EN ISO
27、 6974-2:2012 (E) DIN EN ISO 6974-2:2012-11 3 IntroductionISO 6974 describes methods of analysis of natural gas and methods for calculating component mole fractions and uncertainties. ISO 6974 (all parts) is intended for the measurement of H2, He, O2, N2, CO2and hydrocarbons, either as individual com
28、ponents or as a group, for example all hydrocarbons above C5, defined as C6+. This approach is suitable for a range of end applications, including calibrating gas mixtures and providing natural gas composition and uncertainty data to be used in the calculation of calorific value and other additive p
29、hysical properties of the gas. Details of these end applications are provided in ISO 6974-3 and subsequent parts of ISO 6974.ISO 6974-1 gives guidelines for calculating the mole composition of natural gas, determined using one of the gas chromatographic methods described in ISO 6974-3 and subsequent
30、 parts of ISO 6974. ISO 6974-1 also describes all the essential steps for setting up an analysis, including outlining the structure of the analysis, defining the working ranges and establishing the analytical procedure. This part of ISO 6974 describes the steps required to calculate the uncertainty
31、of the component mole fractions of natural gas determined using gas chromatography.ISO 6974-3 and subsequent parts of ISO 6974 describe different gas chromatographic methods. These methods cover both daily practice in the laboratory and on-line field applications. ISO 6974-1:2012, Annex A, provides
32、a comparison of the characteristics of the analytical methods described in ISO 6974-3 and subsequent parts of ISO 6974.It is intended that this part of ISO 6974 be used in conjunction with ISO 6974-1 and a method of analysis, e.g. ISO 6974-3 or subsequent parts of ISO 6974.ISO 6974-1:2012, 5.5, desc
33、ribes the conventional normalization approach for calculating processed mole fractions from raw mole fractions. When conventional normalization is used for multiple operation methods without bridging, the uncertainties of the calculated mole fractions will be conservative. If a more accurate assessm
34、ent of uncertainty is required, an alternative approach to normalization, using the generalized least squares (GLS) method, can be used; this is described in ISO 6974-1:2012, Annex B. Further alternative approaches are available for calculating processed mole fractions, including methane-by-differen
35、ce (see ISO 6974-1:2012, Annex C) and data harmonization (see Reference 1).EN ISO 6974-2:2012 (E) DIN EN ISO 6974-2:2012-11 41 ScopeThis part of ISO 6974 describes the process required to determine the uncertainty associated with the mole fraction for each component from a natural gas analysis in ac
36、cordance with ISO 6974-1. 2 Normative referencesThe following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.IS
37、O 6974-1:2012, Natural gas Determination of composition and associated uncertainty by gas chromatography Part 1: General guidelines and calculation of compositionISO/IEC Guide 98-3, Uncertainty of measurement Part 3: Guide to the expression of uncertainty in measurement (GUM:1995)3 Terms and definit
38、ionsFor the purposes of this document, the terms and definitions given in ISO 6974-1 apply.4 Symbols4.1 Symbolsbzparameters of the regression function (z = 0, 1, 2 or 3)bzmean parameters of the regression function (in “mean normalization” method)Cisensitivity coefficientk coverage factorK relative r
39、esponse factor with respect to the reference componentnitotal number of components (direct plus indirect, but excluding “other components”)njtotal number of gas standards or mixturesnltotal number of injections (and therefore total number of responses)s standard deviationT total mole fraction of all
40、 raw componentsEN ISO 6974-2:2012 (E) DIN EN ISO 6974-2:2012-11 5 u() standard uncertainty (of the quantity in parentheses)U() expanded uncertainty (of the quantity in parentheses)x normalized mole fractionx*raw mole fractionx mole fraction calculated using the methane-by-difference approach Annex A
41、x adjusted mole fraction Annex Cy instrumental response of the specified analytey mean instrumental response (in “mean normalization” method)y adjusted instrumental response Annex CY instrumental response Annex C intercept of a first-order calibration function Annex C gradient of a first-order calib
42、ration function Annex C gradient of the calibration curve Annex Cmean of the distribution of non-linearity errors4.2 Subscriptscal calibration Annex Ai componentind components or groups of components to be analysed by indirect measurementj gas standard/mixturel injectionoc other componentsp, q indic
43、es defining a regression coefficientref reference (component or pressure)s index defining a componentwms working measurement standard5 Calculation of uncertainty5.1 General considerationsThe process of setting up a gas chromatograph for the analysis of natural gas consists of the steps outlined in t
44、he flowcharts in Figures 1 and 2.Steps 1 to 8 are covered in ISO 6974-1. This part of ISO 6974 covers steps 9 and 10.EN ISO 6974-2:2012 (E) DIN EN ISO 6974-2:2012-11 6START Primary calibration Determine analysis function: (a) Selection of reference gases (b) Measurement of reference gases (c) Regres
45、sion analysis (d) Selection of regression function Performance evaluation Determine initial analysis function (a) Selection of reference gases (b) Measurement of reference gases (c) Regression analysis Step 4 Is primary calibration or performance evaluation required? Type 1 or Type 2 analysis? No Ye
46、s Type 1 Type 2 Are there any indirect components? No Yes Step 1: Define the working range ISO 6974-1:2012, 6.2Step 2: Define the requirements of the analytical method Step 5: Assign relative response factorsStep 3: Select equipment and working conditions FLOWCHART B ISO 6974-1:2012, 6.3ISO 6974-1:2
47、012, 6.4ISO 6974-1:2012, 6.5ISO 6974-1:2012, 6.6Figure 1 Procedure for determining mole fraction and uncertainty Steps 1 to 5EN ISO 6974-2:2012 (E) DIN EN ISO 6974-2:2012-11 7 START FROM FLOWCHART A QA with a WMSRC with a WMS QA check RC Step 6 Quality assurance(QA) check or routine calibration (RC)?Yes Step 8: Calculation of component mole fractions Step 7: Analysis of samplesWill the analyser be used for routine operation?No Are uncertainties of component mole fractions required? FINISH Yes No Step 9: Calculation of uncert
