ISO INTERNATIONAL STANDARD 4126-5 Secondedition 2013-07-15 Safety devices for protection against excessivepressure- Part 5: Controlled safety pressure relief systems (CSPRS) Dispositifs de sécurite pour protection contre les pressions excessives Partie 5:Dispositifs de sécuritéasservis (CSPRS) Reference number IS0 4126-5:2013(E) LSO @IS02013 Copyright International Organization for Standardizatior license from IHS Not for Resale IS04126-5:2013(E) COPYRIGHTPROTECTEDDOCUMENT ISO2013 All rights reserved. Unless otherwise specified, 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 Case postale 56.CH-1211 Geneva 20 Tel. + 4122 749 0111 Fax +41 22 749 09 47 E-mail [email protected] Web www.iso.org Published in Switzerland @ IS0 2013 - All rights reserved No reproduction or networking permited without license from IHS Not for Resale IS04126-5:2013(E) Contents Page Foreword ..iv 1 Scope 2 Normative references 3 Terms and definitions 4 Symbols and units 5 Design ..7 5.1 General .7 5.2 Valveendconnections 5.3 Minimum requirements for springs .10 5.4 Materials. ..10 6 Production testing .10 6.1 Purpose. .10 6.2 General 10 6.3 Hydrostatic testing .11 6.4 Pneumatic testing .11 6.5 Adjustment of set or cold differential test pressure ..12 6.6 Seat leakage test. ..12 6.7 Pressure seals 12 7 Type testing. .12 7.1 General .12 7.2 Tests to determine operating characteristics .14 7.3 Tests to determine flow characteristics. .15 7.4 Determination of the coefficient of discharge ..17 7.5 Certification of coefficient of discharge ..17 7.6 CertificationofCSPRS ..17 8 Determination ofCSPRSperformance ..17 9 Sizingof CSPRS ..17 10 Marking and sealing ..18 10.1 Marking ..18 10.2 Sealing of a CSPRS .19 Bibliography .20 iii IHS under lic nse with IS withoutlicense from IHS Not for Resale