1、Designation:D524221Standard Test Method forOpen-Channel Flow Measurement of Water with Thin-PlateWeirs1This standard is issued under the fixed designation D5242;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revisio
2、n.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This test method covers measurement of the volumetricflow rate of water and wastewater in channels with thin-plateweirs.Information rel
3、ated to this test method can be found inRantz(1)2and Ackers(2).1.2 The values stated in inch-pound units are to be regardedas standard.The values given in parentheses are mathematicalconversions to SI units that are provided for information onlyand are not considered standard.1.3 This standard does
4、not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety,health,and environmental practices and deter-mine the applicability of regulatory limitations prior to use.1.4 This international stan
5、dard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade(TBT)Committee.2.Refer
6、enced Documents2.1 ASTM Standards:3D1129 Terminology Relating to WaterD2777 Practice for Determination of Precision and Bias ofApplicable Test Methods of Committee D19 on WaterD3858 Test Method for Open-Channel Flow Measurementof Water by Velocity-Area Method2.2 ISO Standards:4ISO 1438 Flow Measurem
7、ent in Open Channels Using Weirsand Venturi FlumesPart 1:Thin-Plate WeirsISO 555 Liquid Flow Measurement in Open Channels,Delusion Methods for Measurement of Steady Flow-Constant Rate Injection Method3.Terminology3.1 Definitions:3.1.1 For definitions of terms used in this standard,refer toTerminolog
8、y D1129.3.2 Definitions of Terms Specific to This Standard:3.2.1 crest,nthe bottom of the overflow section or notchof a rectangular weir.3.2.2 head,nthe height of a liquid above a specified point,for example,the weir crest.3.2.3 hydraulic jump,nan abrupt transition from super-critical flow to subcri
9、tical or tranquil flow.3.2.4 nappe,nthe curved sheet or jet of water overfallingthe weir.3.2.5 notch,nthe overflow section of a triangular weir orof a rectangular weir with side contractions.3.2.6 primary instrument,nthe device(in this case theweir)that creates a hydrodynamic condition that can be s
10、ensedby the secondary instrument.3.2.7 scow float,nan in-stream float for depth sensing,usually mounted on a hinged cantilever.3.2.8 secondary instrument,nin this case,a device thatmeasures the depth of flow(referenced to the crest)at anappropriate location upstream of the weir plate.The secondaryin
11、strument may also convert the measured depth to an indi-cated flow rate.3.2.9 stilling well,na small free-surface reservoir con-nected through a constricted channel to the approach channelupstream of the weir so that a depth(head)measurement can bemade under quiescent conditions.1This test method is
12、 under the jurisdiction of ASTM Committee D19 on Waterand is the direct responsibility of Subcommittee D19.07 on Sediments,Geomorphology,and Open-Channel Flow.Current edition approved Dec.15,2021.Published January 2022.Originallyapproved in 1992.Last previous edition approved in 2013 as D5242 92(201
13、3).DOI:10.1520/D5242-21.2The boldface numbers in parentheses refer to a list of references at the end ofthe text.3For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the stan
14、dards Document Summary page onthe ASTM website.4Available from American National Standards Institute(ANSI),25 W.43rd St.,4th Floor,New York,NY 10036,http:/www.ansi.org.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United StatesThis international stand
15、ard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade(TBT)Committee.13.2.10 su
16、bcritical flow,nopen channel flow in which theaverage velocity is less than the square root of the product ofthe average depth and the acceleration due to gravity;some-times called tranquil flow.3.2.11 submergence,na condition where the water levelon the downstream side of the weir is at the same or at a higherelevation than the weir crest;depending on the percent ofsubmergence the flow over the weir and hence the head-discharge relation may be altered.3.2.12 supercritical flow,nopen channel flo
