ISO INTERNATIONAL STANDARD 12242 First edition 2012-07-01 Measurement of fluid flow in closed conduits Ultrasonic transit-time meters for liquid Mesurage de debit des fluides dans les conduites fermees - Compteurs ultrasoniques pour liquides Reference number ISO 12242:2012(E) ISO ISO2012 py IHS under lic n or networking permitted without license from IHS Not for Resale ISO 12242:2012(E) COPYRIGHTPROTECTEDDOCUMENT ISO2012 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or ISO's member body in the country of the requester. ISO copyright office Case postale 56 · CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail [email protected] Web www.iso.org Published in Switzerland @ ISO 2012 -All rights reserved No reproductic etworking permitted without license from IHS Not for Resale ISO 12242:2012(E) Contents Page Foreword Introduction vi 1 Scope. 2 Normative references. 3 Terms and definitions. 3.1 Quantities 3.2 Meterdesign. 2 3.3 Thermodynamic conditions.. 3.4 3 3.5 Calibration. 3.6 Symbols and subscripts.. 5 3.7 Abbreviated terms.. 4 Principles of measurement. 7 4.1 Description.. 4.2 Volume flow.. 4.3 Generic description. 10 4.4 Time delay considerations 4.5 Refraction considerations. 14 4.6 Reynolds number.... 15 15 4.7 Temperatureandpressurecorrection 5 Performance requirements. 15 6 Uncertainty in measurement.. 6.1 Introduction.. 16 6.2 Evaluation of the uncertainty components L Installation 7.1 General .18 7.2 Use of a prover.... 7.3 Calibration in a laboratory or use of a theoretical prediction procedure. 19 7.4 Additional installation effects.... .21 8 Test and calibration . 22 8.1 General.... 22 8.2 Individual testing Use of a theoretical prediction procedure. 22 8.3 Individual testing [ Flow calibration under flowing conditions... 23 9 Performance testing 24 9.1 Introduction.... 24 9.2 Repeatabilityandreproducibility....... .25 9.3 Additional test for meters with externally mounted transducers. .25 9.4 Assessing the uncertainty of a meter whose performance is predicted using a theoretical prediction procedure.... .26 9.5 Fluid-mechanical installation conditions.. 26 9.6 Path failure simulation and exchange of components 27 10 Meter characteristics. 27 10.1 Meter body, materials, and construction 27 10.2 Transducers..... 29 10.3 Electronics 29 10.4 Software.. 30 10.5 Exchange of components .31 10.6 Determination of density and temperature 31 11 Operational practice 32 11.1 General.. .32 ili nse with IS ted withoutlicensefrom IHS Not for Resale