400 Commonwealth Drive, Warrendale, PA 15096-0001 U.S.A. Tel: (724) 776-4841 Fax: (724) 776-5760 Web: www.sae.org SAE TECHNICAL PAPER SERIES 2006-01-0379 Simplifying the Approach to Specify and Measure Venu Gorti and Hemi Sagi Advanced Test Concepts (ATC), Inc. 2006 SAE World Congress Detroit, Michigan April 3-6, 2006 Product Seal Integrity and Leak Tightness Downloaded from SAE International by Univ of California Berkeley, Thursday, August 02, 2018The Engineering Meetings Board has approved this paper for publication. It has successfully completed SAE's peer review process under th e supervision of the session organi zer. This process requires a minimum of three (3) reviews by industry experts. All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of SAE. For permission and licensing requests contact: SAE Permissions 400 Commonwealth DriveWarrendale, PA 15096-0001-USAEmail: [email protected]: 724-772-4028 Fax: 724-776-3036 For multiple print copies contact: SAE Customer Service Tel: 877-606-7323 (inside USA and Canada)Tel: 724-776-4970 (outside USA)Fax: 724-776-0790Email: [email protected] ISSN 0148-7191 Copyright © 2006 SAE International Positions and opinions advanced in this paper are those of the author(s ) and not necessarily those of SAE. The author is solely responsible for the content of th e paper. A process is available by which discussions will be printed with the pap er if it is publishe d in SAE Transactions. Persons wishing to submit papers to be considered for presentation or publicat ion by SAE should send the manuscript or a 300 word abstract to Secretary, Engineering Meetings Board, SAE. Printed in USADownloaded from SAE International by Univ of California Berkeley, Thursday, August 02, 20182006-01-0379 Simplifying the Approach to Specify and Measure Product Seal Integrity and Leak Tightness Venu Gorti and Hemi Sagi Advanced Test Concepts (ATC), Inc. Copyright © 2006 SAE International The total permissible emissions for fuels, hydrocarbon vapors, oil coolants and refrigerants are typically defined by mass flow rates (mg/day, mg/year etc.) of the specific fluid. The emission is a result of diffusive permeation and fluid leakage. There is an increasing requirement for elimination or reduction of emissions due to leakage. Therefore, product engineers, process engineers and quality engineers need to find a way to translate the requirements into production specifications, where, typically, air or tracer gases (like helium) are used for leak testing. ABSTRACT A common problem encountered when designing a new product for demanding environmental conditions is specifying its leak tightne ss and measuring its seal integrity. Correlating empirical test data to production leak testing is an on-going challenge and a major source of confusion. Products of interest are those in automotive fuel and vapor management systems, A/C and cooling systems and power-train components and systems. Conventionally, production leak tightness specifications have been set in terms of the maximum allowed gas flow (air or tracer gases such as helium) at test conditions, for a given gas. The drawback of this method is its dependence on the leak test method used, thus creating difficulties in correlations and causing confusion in users not familiar with flow terminology. A simple solution to the problem is proposed in this paper, based on defining the maximum acceptable microchannel geometry called the Equivalent Micro Geometry (EMG). Various mechanisms of fluid transport through microchannels are summarized. Flow through two types of EMGs, sharp edged orifices and microchannels, are examined. A practical implementation of the EMG approach to determine leak tightness specifications of compon