ISO INTERNATIONAL STANDARD 15112 Third edition 2018-11 Natural gas - Energy determination Gaz naturel -Détermination de I'énergie Referencenumber IS0 15112:2018(E) ISO @IS02018 IS0 15112:2018(E) COPYRIGHTPROTECTEDDOCUMENT IS02018 All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting below or Iso's member body in the country of the requester. ISO copyright office CP 401 : Ch. de Blandonnet 8 CH-1214 Vernier, Geneva Phone:+4122749 0111 Fax: +41 22 749 09 47 Email: [email protected] Website: www.iso.org Published in Switzerland ii @ IS0 2018 - All rights reserved IS0 15112:2018(E) Contents Page Foreword ..V Introduction. ..vi 1 Scope. 2 Normative references 3 Terms and definitions 4 Symbols and units 5 General Principles. ..7 6 Gas measurement .8 6.1 General .8 6.2 Volumemeasurement. 9 6.3 Calorific value measurement. 9 Measurement techniques and sampling. ..9 6.3.1 6.3.2 Direct measurement-Calorimetry .10 6.3.3 Inferential measurement ..10 6.3.4 Correlation techniques. .10 6.3.5 Pressure and temperature .10 6.3.6 Gas quality tracking. .10 6.4 Volume conversion .10 6.4.1 General. .10 6.4.2 Density .11 .11 6.4.3 Compressionfactor. 6.5 Calibration .11 6.6 Data storage and transmission. ..11 7 Energy determination .12 7.1 Interfaces. ..12 7.2 Methods ofenergydetermination ..14 7.2.1 Direct determination of energy ..14 7.2.2 Indirect determination of energy ..14 8 Strategy and procedures ..16 8.1 General ..16 8.2 Strategiesfor energydetermination ..17 8.2.1 Strategies for single interfaces. .18 8.3 Plausibility checks. .22 9 Assignment methods. .23 9.1 Fixed assignment. 23 9.1.1 Fixed assignment of a measured calorific value 23 9.1.2 Fixed assignment of a declared calorific value 24 9.2 Variable assignment. .25 9.2.1 Inputattwoormoredifferentstationswithzerofloatingpoint .25 9.2.2 Inputattwo ormoredifferentstationswithcomingledgasflows .26 9.3 Determination of the representative calorific value. .27 9.3.1 .27 Arithmetically averaged calorificvalue. 9.3.2 Quantity-weighted average calorific value .27 9.3.3 Gas quality tracking. .27 10 Calculation of energy quantities .30 10.1 General formulaefor energy... ..30 10.2 Calculation ofaveraged valuesCalculation from average calorific values and ..31 cumulativevolumes.. 10.2.1 Arithmetic averageof the calorificvalue .31 Quantity-weighted average of the calorific value ..32 10.2.2 @ IS0 2018 -All rights reserved iii