ISO INTERNATIONAL STANDARD 14511 Second edition 2019-01 Measurement of fluid flow in closed conduits Thermal mass flowmeters Mesure de débit des fluides dans les conduites fermées -Débitmetres massiques par effet thermique Reference number IS0 14511:2019(E) so @ IS0 2019 IS0 14511:2019(E) COPYRIGHTPROTECTEDDOCUMENT @ ISO 2019 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 on the internet or an intranet, without prior written permission. Permission can be requested from either IsO at the address 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: +4122 749 0111 Fax: +41 22 749 09 47 Email: copyright@iso.org Website: www.iso.org Published in Switzerland ii @ IS0 2019 - All rights reserved IS0 14511:2019(E) Contents Page Foreword ..V Introduction. ...vi 1 Scope. 2 Normative references 3 Terms and definitions 3.1 General terms. ..1 3.2 Specific terms. 4 Selection of thermal mass flowmeters ..4 5 Capillary thermal mass flowmeter (CTMF meter) .5 5.1 Principles of measurement .5 5.2 Typical design. ..8 5.3 Applications and limitations of use ..8 5.3.1 Gas property effects ..8 5.3.2 Application and fluid properties 9 5.3.3 Temperature effects .9 5.3.4 Pressure effects. .9 5.3.5 Pulsation effects .9 5.3.6 Pressure loss. 9 5.3.7 Cleanness of the gas. .9 5.3.8 Mounting orientation effects.. 5.3.9 Installation effects for flow profile .10 5.3.10 Vibrations Hydraulic and mechanical .10 5.3.11 Valves. .10 5.4 Meter selection .10 5.4.1 Principal requirement. ..10 5.4.2 Performance specifications .10 5.4.3 Physical specifications .10 5.4.4 Meter ratings .11 5.4.5 Application and fluid properties .11 5.4.6 Corrosion. .11 5.4.7 Transmitter specifications ..11 5.5 Installation and commissioning .11 5.5.1 General considerations .11 5.5.2 Safety. .12 5.5.3 Mechanical stress .12 5.5.4 Process adjustment ..12 6 Insertion and/or in-line thermal mass flowmeter (ITMF meter) ..13 6.1 Principle of measurement ..13 ..13 6.1.1 General 6.1.2 Constant power method .14 6.1.3 Constant-temperature-differential method ..15 6.2 Typical design .16 6.2.1 ITMF basic design ..16 6.2.2 In-line ITMF meter. ..16 6.2.3 Insertion-ITMF meter ..17 6.2.4 Multi-point insertion-ITMF meter ..18 6.3 Applications and limitations of use. .18 6.3.1 General remarks. ..18 6.3.2 Normalized volume flowrate units ..18 6.3.3 Fluid property effects ..18 6.3.4 Temperature effects. ..19 6.3.5 Pressure effects.. ..19 IS0 2019 - All rights reserved iii