ISO INTERNATIONAL STANDARD 23551-2 Second edition 2018-09 Safety and control devices for gas burners and gas-burning appliances Particular requirements Part 2: Pressure regulators Dispositifs de commande et de sécurite pour bruleurs a gaz et appareils a gaz - Exigences particulieres Partie 2: Régulateurs de pression Reference number IS0 23551-2:2018(E) ISO @IS02018 IS0 23551-2:2018(E) COPYRIGHTPROTECTEDDOCUMENT @ IS0 2018 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 onthe internet or an intranet, without prior writtenpermission.Permission can be requested from either Iso at the address below or Iso's memberbody in the country ofthe requester. ISO copyright office CP 401 : Ch. de Blandonnet 8 CH-1214 Vernier, Geneva Phone: +41 22 749 01 11 Fax: +4122 749 09 47 Email: copyright@iso.org Website: www.iso.org Published in Switzerland ii IS02018-Allrightsreserved IS023551-2:2018(E) Contents Page Foreword ..V Introduction ..vii 1 Scope. ..1 2 Normative references .2 3 Terms and definitions 3.1 Pressure regulators. .2 3.2 Pressures.... .2 3.3 Flow rates. 4 3.4 Component parts. ..4 3.5 Performance .5 Classification 4 .6 4.1 Classes of control .6 4.2 Groups of controls. ..6 4.3 Types of DC supplied controls .6 5 Test conditions. ..7 6 Construction. 6.1 General. 7 6.2 Construction requirements .7 6.2.1 Appearance. 7 6.2.2 Holes. .7 6.2.3 Breather holes .7 Vent limiters.. 6.2.4 .7 6.2.5 Screwed fastenings 6.2.6 Moving parts. .7 6.2.7 Sealing caps. 6.2.8 Disassembling and assembling for servicing and/or adjustment 7 .1 6.2.9 Auxiliarychannelsandorifices 6.2.10 Pre-setting device 7 6.2.11 Adjustments .8 6.2.12 Resistance to pressure .8 6.2.13 Blockage of canals and orifices .8 6.2.14 Signal tube connections. .8 6.3 Materials. .8 6.3.1 General material requirements. 6.3.2 Housing .8 6.3.3 Springs providing closing force and sealing force ..9 6.3.4 Resistance to corrosion and surface protection 9 6.3.5 .9 Impregnation 6.3.6 Seals for glands for moving parts 9 6.3.7 Jointing 9 6.4 Connections. 9 6.4.1 General. 9 6.4.2 Connection sizes. 9 Connection types 6.4.3 .9 6.4.4 Threads .9 6.4.5 Union joints. 9 .9 6.4.6 Flanges. 6.4.7 Compression fittings. 9 Flare connections. 6.4.8 Nipples for pressure test 6.4.9 .9 6.4.10 Strainers. .10 6.4.11 ..10 Gas connections by GQC @ IS0 2018 - All rights reserved iii