ISO INTERNATIONAL STANDARD 5136 Second edition 2003-04-01 Acoustics Determination of sound power radiated into a duct by fans and other air-moving devices In-duct method Acoustique Détermination de la puissance acoustique rayonnee dans un conduit par des ventilateurs et d'autres systemes de ventilationMethodeenconduit Reference number ISO 5136:2003(E) ISO @ ISO 2003 by IHS under lic ted without license from IHS Not for Resale ISO 5136:2003(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 parameters were optimized for printing. Every care has been taken to ensure that the file is suitable for use by IsO member bodies. In the unlikely event that a problem relating to it is found, please inform the Central Secretariat at the address given below. @ISO2003 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, 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 Copyrihtinteratinal organization for Standardization @IsO2003-All rightsreserved py IHS unde ermitted without license from IHS Not for Resale ISO 5136:2003(E) Contents Page Foreword V Introduction 1 Scope. 1.1 General. 1.2 Types of sound source. 2 Normative references ... 3 Terms, definitions and symbols .... 4 Uncertainty of the measurement method.... 5 Test facilities and instrumentation... 5.1 General requirements .... 5.2 Duct specifications ... 9 5.3 Instrumentation ... 16 5.4 System calibration 19 6 Test arrangement ... 6.1 Sampling tube mounting .. 20 6.2 Microphone position... 20 6.3 Operating condition control equipment . 21 7 Test procedure .... 21 7.1 Operatingconditions 21 7.2 Sound pressure level readings.. 21 7.3 Measurements with and without flow straightener on the outlet side ...... .22 7.4 Inlet side measurements - Large fans: installation category D (according to ISO 5801:1997)... 8 Calculations.. 8.1 Average sound pressure level. .23 8.2 Sound power level . 23 9 Information to be recorded ... 10 Information to be reported .. Annex A (normative) Determination of the combined mean flow velocity and modal correction Annex B (normative) Determination of the signal-to-noise ratio of sound vs. turbulent pressure fluctuation in the test duct .... Annex C (normative) Computational procedures for calculating the A-weighted sound power level from onethird..octave.band sound power levels.......... Annex D (informative) Example of calculation of C3,4 for a given duct diameter and mean flow velo.c.ity......... Annex E (informative) Guidelines for the design and construction of an anechoic termination .... 38 AnnexF(informative)Evaluationofperformanceofanechoicterminations... ...47 Annex G (informative) Sampling tube information.... ..50 Annex H (informative) Test method for small ducted fans.... Annex I (informative) Test method for large ducted fans... .58 Annex J (informative) Measurement of the swirl component... .65 Bibliography Copyrght International Organizaion forstandardizationrights reserved ii ted without license from IHS Not for Resale ISO 5136:2003(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 committee