ISO INTERNATIONAL STANDARD 23820 First edition 2023-05 Determination of the filtration efficiency of urea filter modules Détermination de I'efficacite de filtration des modules de filtres a uree Reference number IS0 23820:2023(E) so IS02023 IS0 23820:2023(E) COPYRIGHT PROTECTED DOCUMENT @IS02023 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 Email: [email protected] Website: www.iso.org Published in Switzerland ii @IS0 2023 - All rights reserved