-1-2_Edtn_2004.pdf

AN AMERICA N NATIO NA L STA NDA RDAir Gaps in?Plumbing Systems?(For Plumbing Fixtures and Water-Connected Receptors)ASME A112.1.2-2004(Revision of ASME A112.1.2-1991)Copyrighted material licensed to Stanford University by Thomson Scientific(),downloaded on Oct-05-2010 by Stanford University User.No further reproduction or distribution is permitted.Uncontrolled when printed.ANAMERICANNATIONALSTANDARDAIRGAPSINPLUMBINGSYSTEMS(FORPLUMBINGFIXTURESANDWATER-CONNECTEDRECEPTORS)ASMEA112.1.2-2004(RevisionofASMEA112.1.2-1991)Copyrighted material licensed to Stanford University by Thomson Scientific(),downloaded on Oct-05-2010 by Stanford University User.No further reproduction or distribution is permitted.Uncontrolled when printed.Date of Issuance:October 15,2004The next edition of this Standard is scheduled for publication in 2009.There will be no addendaissued to this edition.ASME issues written replies to inquiries concerning interpretations of technical aspects of thisStandard.Interpretations are published on the ASME Web site under the Committee Pages at http:/www.asme.org/codes/as they are issued.ASME is the registered trademark of The American Society of Mechanical Engineers.This code or standard was developed under procedures accredited as meeting the criteria for American NationalStandards.The Standards Committee that approved the code or standard was balanced to assure that individuals fromcompetent and concerned interests have had an opportunity to participate.The proposed code or standard was madeavailable forpublic review andcomment thatprovides an opportunityfor additional publicinput from industry,academia,regulatory agencies,and the public-at-large.ASME does not“approve,”“rate,”or“endorse”any item,construction,proprietary device,or activity.ASME does not take any position with respect to the validity of any patent rights asserted in connection with anyitems mentioned in this document,and does not undertake to insure anyone utilizing a standard against liability forinfringement of any applicable letters patent,nor assume any such liability.Users of a code or standard are expresslyadvised that determination of the validity of any such patent rights,and the risk of infringement of such rights,isentirely their own responsibility.Participation by federal agency representative(s)or person(s)affiliated with industry is not to be interpreted asgovernment or industry endorsement of this code or standard.ASME accepts responsibility for only those interpretations of this document issued in accordance with the establishedASME procedures and policies,which precludes the issuance of interpretations by individuals.No part of this document may be reproduced in any form,in an electronic retrieval system or otherwise,without the prior written permission of the publisher.The American Society of Mechanical EngineersThree Park Avenue,New York,NY 10016-5990Copyright 2004 byTHE AMERICAN SOCIETY OF MECHANICAL ENGINEERSAll rights reservedPrinted in U.S.A.Copyrighted material licensed to Stanford University by Thomson Scientific(),downloaded on Oct-05-2010 by Stanford University User.No further reproduction or distribution is permitted.Uncontrolled when printed.CONTENTSForeword.ivCommittee Roster.vCorrespondence With the A112 Committee.vi1General.12Requirements.2Figures1Example of Air Gap and Effective Opening.22Example of Near-Wall Influence on Air Gap.3Table1Minimum Air Gaps for Generally Used Plumbing Fixtures.4Nonmandatory AppendicesAMethod of Providing an Air Gap for Tanks or Vats With Water Inlets Belowthe Flood-Level Rim.5BOther Standards Applicable to Backflow Prevention.6iiiCopyrighted material licensed to Stanford University by Thomson Scientific(),downloaded on Oct-05-2010 by Stanford University User.No further reproduction or distribution is permitted.Uncontrolled when printed.FOREWORDThe Sectional Committee on Minimum Requirements for Plumbing and Standardization ofPlumbing Equipment,A40,realizing the need for regulations and devices to protect the purityof water supplies in buildings,organized a technical subcommittee on air gaps and backflowpreventers in 1938.This subgroup completed a tentative draft of a proposed standard for airgaps for a meeting of Subcommittee 12 on January 20,1939.The draft proposal was considered and revised.Copies of this revised report were distributedto interested firms and individuals in industry for further criticism and comment.At the Octobermeeting of the subcommittee,the comments received were carefully considered.The April 1940draft was distributed to the members of Sectional Committee A40 for discussion.Certain changeswererecommendedandtwosectionscoveringwaterinletstotankshavingoverflowsanddrinkingfountain bubblers were added.These were incorporated into the revised draft dated May 1940.Copies of this draft were distributed to the members of the sectional committee and to a groupof more than 100 health supervisory officials,plumbing inspectors,state plumbing associations,and other