1、BS ISO15971:2008ICS 75.060NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBRITISH STANDARDNatural gas Measurement ofproperties C alorificvalue and Wobbe indexBS EN ISO 15971:2014BS EN ISO 15971:2014ISBN 978 0 580 83401 1Amendments/corrigenda issued since publicationDate Comment
2、s31 May 2014 This corrigendum renumbers BS ISO 15971:2008 as BS EN ISO 15971:2014.This British Standard was published under the authority of the Standards Policy and Strategy Committee on 31 January 2009 The British Standards Institution 2014. Published by BSI Standards Limited 2014National foreword
3、This British Standard is the UK implementation of EN ISO 15971:2014. It is identical to ISO 15971:2008. It supersedes BS ISO 15971:2008 which is withdrawn.The UK participation in its preparation was entrusted to Technical Committee PTI/15, Natural Gas and Gas Analysis.A list of organizations represe
4、nted on this committee can be obtained on request to its secretary.The publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application.Compliance with a British Standard cannot confer immunity from legal obligations.EUROPEAN STAND
5、ARD NORME EUROPENNE EUROPISCHE NORM EN ISO 15971 March 2014 ICS 75.060 English Version Natural gas - Measurement of properties - Calorific value and Wobbe index (ISO 15971:2008) Gaz naturel - Mesurage des proprits - Pouvoir calorifique et indice de Wobbe (ISO 15971:2008) Erdgas - Messung der Eigensc
6、haften - Wrmewerte und Wobbe-Index (ISO 15971:2008) This European Standard was approved by CEN on 16 February 2014. 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
7、 alteration. Up-to-date lists and bibliographical 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 languag
8、e made by translation under the responsibility 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,
9、Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United Kingdom. EUROPEAN COMMITTEE FOR
10、STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels 2014 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN ISO 15971:2014 EEN ISO 15971:2014 (
11、E) 3 Foreword The text of ISO 15971:2008 has been prepared by Technical Committee ISO/TC 193 “Natural gas” of the International Organization for Standardization (ISO) and has been taken over as EN ISO 15971:2014. This European Standard shall be given the status of a national standard, either by publ
12、ication of an identical text or by endorsement, at the latest by September 2014, and conflicting national standards shall be withdrawn at the latest by September 2014. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN and/or CEN
13、ELEC shall not be held responsible for identifying any or all such patent rights. According 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 Repub
14、lic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom. Endor
15、sement notice The text of ISO 15971:2008 has been approved by CEN as EN ISO 15971:2014 without any modification. BS EN ISO 15971:2014EN ISO 15971:2014 (E)BS ISO 15971:2008ISO 15971:2008(E) ISO 2008 All rights reserved iiiContents PageForeword ivIntroduction v1Scope. 12Normative references. 13Terms a
16、nd definitions. 13.1 Calorific value and Wobbe index 13.2 Water content of gas 23.3 Performance classification 23.4 Terms from metrology 34Principles of measurement 44.1 Introduction. 44.2 Direct combustion calorimetry 54.3 Indirect methods. 54.4 Inferential methods. 65Performance assessment and acc
17、eptance tests.75.1 Performance assessment for instrument selection 75.2 Factory and site acceptance tests 206Sampling and installation guidelines . 216.1 Sampling 216.2 Installation guidelines 227Calibration. 257.1 Calibration procedures. 257.2 Calibration gases 268Verification 278.1 Verification pr
18、ocedures 278.2 Verification gases. 289Maintenance 299.1 Preventive maintenance. 299.2 Corrective maintenance. 2910 Quality control. 2910.1 General. 2910.2 Environmental parameters and ancillary equipment 3110.3 Instrumental factors . 32Annex A (normative) Symbols and units.33Annex B (informative) Ex
19、amples of type-approval and technical specifications 34Annex C (informative) Class 0 mass-basis calorimetry. 36Annex D (informative) Direct combustion calorimetry. 40Annex E (informative) Stoichiometric combustion devices.43Annex F (informative) Effect of non-alkane gases on stoichiometric combustio
20、n devices.47Annex G (informative) Measurement of Wobbe index 48Bibliography. 49BS EN ISO 15971:2014ISO 15971:2008(E)BS ISO 15971:2008ISO 15971:2008(E)iv ISO 2008 All rights reservedForeword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodie
21、s (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member bodyinterested in a subject for which a technical committee has beenestablished has the right to be represented on that committee. International organizations, g
22、overnmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closelywith the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IE
23、C Directives, Part 2.The main task of technical committees is to prepare International Standards. Draft International Standardsadopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member
24、 bodies casting a vote. 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 such patent rights. ISO 15971 was prepared by Technical Committee ISO/TC 193, Natural gas. BS EN
25、ISO 15971:2014ISO 15971:2008(E)BS ISO 15971:2008ISO 15971:2008(E) ISO 2008 All rights reserved vIntroduction The amount of energy delivered by a flowing natural gas is often determined as the product of the volumedelivered and the calorific value per unit volume of the gas. It is, therefore, importa
26、nt to have available standardized methods of determining the calorific value. In many cases,it is possible to calculate the calorificvalue of natural gas,with sufficient accuracy, given the composition (see ISO6976). However, it is alsopossible, and sometimes a preferred alternative, to measure calo
27、rific value using any one of severaltechniques that do not require a compositional analysis. The methods currentlyin use, and the many factors that it is necessary to address in the selection, evaluation, performance assessment, installation and operation of a suitable instrument, are detailed herei
28、n. The measurement of the Wobbe index, a property closely related to calorific value, is discussed brieflyin an informative annex, but is not considered in detail in the normative parts of this International Standard.BS EN ISO 15971:2014ISO 15971:2008(E)BS ISO 15971:2008BS EN ISO 15971:2014BS ISO 15
29、971:2008INTERNATIONAL STANDARD ISO 15971:2008(E) ISO 2008 All rights reserved 1Natural gas Measurementofproperties C alorific value and Wobbe index1 Scope This International Standard concerns the measurement of calorific value of natural gas and natural gas substitutes by non-separative methods, i.e
30、. methods that do not involve the determination of the gas composition nor calculation from it. It describes the principles of operation of a variety of instruments in use forthis purpose, and provides guidelines for the selection, evaluation, performance assessment, installation andoperation of the
31、se. Calorific values can be expressed on a mass basis, a molar basis or, more commonly, a volume basis. The working range for superior calorific value of natural gas, on the volume basis, is usually between 30 MJ/m3and 45 MJ/m3at standard reference conditions (see ISO 13443). The corresponding range
32、 for the Wobbeindex is usuallybetween 40 MJ/m3and 60 MJ/m3. This International Standard neither endorses nor disputes the claims of any commercial manufacturer for theperformance of an instrument. Its central thesis is that fitness-for-purpose in any particular application (defined in terms of a set
33、 of specific operational requirements) can be assessed only by means of a well-designed programme of experimental tests. Guidelines are provided for the proper content of these tests.2 NormativereferencesThe following referenced documents are indispensable for the application of this document. For d
34、atedreferences, only the edition cited applies. For undated references, the latest edition of the referenceddocument (including any amendments) applies.ISO 6976:1995, Natural gas Calculation of calorific values, density, relative density and Wobbe index from compositionISO 14532: 2001, Natural gas V
35、 ocabulary3 Terms and definitions For the purposes of this document, the following terms and definitions apply.3.1Calorific value and Wobbe index 3.1.1 superior calorific value amount of heat that would be released by the complete combustion in airof a specified quantity of gas (on amolar,mass or vo
36、lume basis), in such a way that the pressure, p, at which the reaction takes place remains constant and all the products of combustion are returned to the same specified temperature, T, as that of the reactants,all of these products being in the gaseous state, except forwater formed by combustion, w
37、hich iscondensed to the liquid state at TSee ISO 6976. BS EN ISO 15971:2014ISO 15971:2008(E)BS ISO 15971:2008ISO 15971:2008(E)2 ISO 2008 All rights reserved3.1.2 inferior calorific value amount of heat that would be released by the complete combustion in airof a specified quantity of gas (on amolar,
38、mass or volume basis), in such a way that the pressure, p, at which the reaction takes place remains constant, and all the products of combustion are returned to the same specified temperature, T, as that of the reactants, all of these products being in the gaseous state See ISO 6976. 3.1.3 Wobbe in
39、dexsuperior calorific value on a volumetric basis at specified reference conditions, divided by the square root ofthe relative density at the same specified metering reference conditionsSee ISO 6976. 3.1.4 standard reference conditionstemperature, T = 288,15 K, and (absolute) pressure, p = 101,325 k
40、Pa, for the realdry gasSee ISO 13443. NOTE Standard reference (or base) conditions of temperature,pressure and humidity (state of saturation) aredefined for use only in natural gas and similar applications. For the calorific value on a volumetric basis, these conditionsapply to both the metering and
41、 combustion of the gas. In the expression of physical quantities throughout this InternationalStandard, these standard reference conditions as defined in ISO 13443 are taken to apply. 3.2Water content of gas 3.2.1 saturated gas natural gas which, at the specified conditions of temperature and pressu
42、re, is at its water dew-point 3.2.2 dry gasnatural gas which does not contain water vapour at a mole fraction greater than 0,000 05 See ISO 6976. 3.2.3 partially saturated or wet gas natural gas which contains an amount of water vapour between that of the saturated gas and that of the dry gas, at th
43、e specified conditions of temperature and pressure 3.3 Performance classification NOTE The following classification scheme is adopted in order to categorize the uncertainties associated with measurement of calorific value. The attached notes are explanatory, not parts of the definitions. The values
44、given refer to an expanded uncertainty with a coverage factor of 2. 3.3.1 class 0 performance with which uncertaintylimits of no greater than 0,1 % in calorific value may be associated NOTE Performance of this quality can currently be achieved only by instruments in which all operations are carriedo
45、ut in strict accordance with the best metrological practices and in which all relevant physical measurements are directlytraceable to primary metrological standards. Typically, such an instrument is custom-built and installed in a purpose-built,environmentally controlled specialist laboratory; a spe
46、cially trained and identified operator is likely required. Instruments of this type are sometimes known as “reference calorimeters” and all, to date, make measurements discontinuously ondiscrete samples of gas. BS EN ISO 15971:2014ISO 15971:2008(E)BS ISO 15971:2008ISO 15971:2008(E) ISO 2008 All righ
47、ts reserved 33.3.2 class 1 performance with which uncertainty limits of no greater than 0,1 MJ/m3on a volume-basis calorific value(approximately0,25 %) may be associated NOTE This is the lowest level of measurement uncertainty currently available for any form of commercial instrumentused in routine
48、field (i.e. non-laboratory) operation. Even for the few types of instrument that are intrinsically capable ofthis performance, it is unlikely to be achieved unless installation is in accordance with both the manufacturersinstructionsand the principles described in this International Standard, and op
49、eration is in accordance with the calibration, verification,maintenance and quality control procedures described in this International Standard. 3.3.3 class 2 performance with which uncertainty limits of no greater than 0,2 MJ/m3on a volume-basis calorific value(approximately0,5 %) may be associated 3.3.4 class 3 performance with which uncertainty limits of no greater than 0,5 MJ/m3on a volume-basis calorific value(approximately1,0 %) may be associated 3.4 Terms frommetrologyNOTE The following definitions, including the Notes attached to th
