BS ISO BRITISHSTANDARD 20765-1:2005 Natural gas - Calculation of thermodynamic properties Part 1: Gas phase properties for transmission and distribution applications ICS 75.060 BSi NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW British Standards BSISO20765-1:2005 National foreword This British Standard is the UK implementation of iSO 20765-1:2005. The UK participation in its preparation was entrusted to Technical Committee PTI/15, Natural gas and gas analysis. A list of organizations represented on this committee can be obtained on request to its secretary. This 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. This British Standard Amendments/corrigenda issued since publication was published under the authority of the Standards Policy and Strategy Date Comments Committee on 28 February 2009 @BSI2009 ISBN 978 0 580667619 BS ISO 20765-1:2005 INTERNATIONAL ISO STANDARD 20765-1 First edition 2005-09-15 Natural gas Calculation of thermodynamic properties Part 1: Gas phase properties for transmission and distribution applications Gaz naturel-Calculdes proprietés thermodynamiques- Partie 1:Proprietés de la phase gazeuse utilisée pourdes applications de transport et de distribution Reference number ISO 20765-1:2005(E) ISO ISO2005 BSISO20765-1:2005 ISO 20765-1:2005(E) PDF disclaimer This PDF file may contain embedded typefaces. In accordance with Adobe's licensing policy, this file may be printed or viewed but shall not be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In accepts no liability in this area. Adobe is a trademark of Adobe Systems Incorporated. Details of the software products used to create this PDF file can be found in the General Info relative to the file; the PDF-creation the unlikely event that a problem relating to it is found, please inform the Central Secretariat at the address given below. ISO2005 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, copy: IsO's member body in the country of the requester. ISO copyright office Case postale 56 · CH-1211 Geneva 20 Licensed Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail [email protected] Web www.iso.org Published in Switzerland ii @ISO2005-Allrightsreserved BSISO20765-1:2005 ISO20765-1:2005(E) BritishStandardsInstitution2013 Contents Page Foreword.. Introduction 1 Scope 2 Normative references... 3 Termsand definitions 4 Thermodynamic basis of the method.. The 4.1 4.2 The fundamental equation of Helmholtz free energy.... 4.3 Thermodynamic properties derived from the Helmholtz free energy. Versioncorrectasof03/01/2015, 5 Method of calculation.. 8 5.1 Input variables... .8 5.2 Conversionfrompressuretoreduceddensity.. 5.3 Implementation.. 6 Rangesofapplication 6.1 Pressureandtemperature .10 6.2 Pipeline quality gas . .10 7 Uncertainty. 11 7.1 Uncertainty for pipeline quality gas... 7.2 Impact ofuncertainties of input variables 8 Reportingof results... .14 AnnexA(normative)Symbols and units.. ..16 Annex B (normative)The Helmholtz free energy of the ideal gas. ..19 Annex C (normative)The equation for the Helmholtz freeenergy .22 AnnexD (normative)Detailed documentationfortheequation of state.. .24 AnnexE(informative)Assignmentoftracecomponents.. ...30 AnnexF(informative)Implementationofthemethod. .32 AnnexG(informative)Examples ..35 Bibliography 42 @ ISO 2005 - All rights reserved ii BS ISO 20765-1:2005 ISO 20765-1:2005(E) Foreword IsO (the International Organization for Standardization) is a worldwide federation of national standards bodies (iSO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical com