UL UL 181 STANDARD FOR SAFETY Factory-Made Air Ducts and Air Connectors ULCOPYRIGHTEDMATERIAL NOTAUTHORIZEDFORFURTHERREPRODUCTIONOR DISTRIBUTIONWITHOUTPERMISSIONFROMUL ULCOPYRIGHTEDMATERIAL NOTAUTHORIZEDFORFURTHERREPRODUCTIONOR DISTRIBUTIONWITHOUTPERMISSIONFROMUL APRIL 18, 2017 - UL 181 tr1 Eleventh Edition, Dated July 25, 2013 Summary of Topics This revision of ANSi/UL 181 is being issued to update the title page to reflect reaffirmation of ANSI approval. Text that has been changed in any manner or impacted by UL's electronic publishing system is marked with a vertical line in the margin. The requirements are substantially in accordance with Proposal(s) on this subject dated February 24, 2017. All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form by any means, electronic, mechanical photocopying, recording, or otherwise without prior permission of UL. not limited to, the implied warranties of merchantability or fitness for any purpose. In no event will UL be liable for any special, incidental, consequential, indirect or similar damages, including loss of profits, lost savings, loss of data, or any other damages arising out of the use of or the inability to use this Standard, even if UL or an authorized UL representative has been advised of the this Standard, regardless of the form of the claim. Users of the electronic versions of UL's Standards for Safety agree to defend, indemnify, and hold UL harmless from and against any loss, expense, liability, damage, claim, or judgment (including reasonable attorney's fees) resulting from any error or deviation introduced while purchaser is storing an electronio Standard on the purchaser's computer system. ULCOPYRIGHTEDMATERIAL NOTAUTHORIZEDFORFURTHERREPRODUCTIONOR DISTRIBUTIONWITHOUTPERMISSIONFROMUL