ASTM_D_5389_-_93_2013.pdf

Designation:D538993(Reapproved 2013)Standard Test Method forOpen-Channel Flow Measurement by Acoustic VelocityMeter Systems1This standard is issued under the fixed designation D5389;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.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 the measurement of flow rate ofwater in open channels,streams,and closed conduits with afree water surface.1.2 The test method covers the use of acoustic transmissionsto measure the average water velocity along a line between oneor more opposing sets of transducersby the time differenceor frequency difference techniques.1.3 The values stated in SI units are to be regarded as thestandard.1.4 This standard does 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 and health practices and determine the applica-bility of regulatory limitations prior to use.Specific precau-tionary statements are given in Section 6.2.Referenced Documents2.1 ASTM Standards:2D1129 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 Standard:3ISO 6416 Liquid Flow Measurements in Open ChannelsMeasurement of Discharge by the Ultrasonic(Acoustic)Method3.Terminology3.1 DefinitionsFor definitions of terms used in this testmethod,refer to Terminology D1129.3.2 Definitions of Terms Specific to This Standard:3.2.1 acoustic paththe straight line between the centers oftwo acoustic transducers.3.2.2 acoustic path lengththe face-to-face distance be-tween transducers on an acoustic path.3.2.3 acoustic transducera device that is used to generateacoustic signals when driven by an electric voltage,andconversely,a device that is used to generate an electric voltagewhen excited by an acoustic signal.3.2.4 acoustic travel timethe time required for an acousticsignal to propagate along an acoustic path,either upstream ordownstream.3.2.5 dischargethe rate of flow expressed in units ofvolume of water per unit of time.The discharge includes anysediment or other materials that may be dissolved or mixedwith it.3.2.6 line velocitythe downstream component of watervelocity averaged over an acoustic path.3.2.7 measurement planethe plane formed by two or moreparallel acoustic paths of different elevations.3.2.8 path velocitythe water velocity averaged over theacoustic path.3.2.9 stagethe height of a water surface above an estab-lished(or arbitrary)datum plane;also gage height.3.2.10 velocity samplingmeans of obtaining line veloci-ties in a measurement plane that are suitable for determiningflow rate by a velocity-area integration.4.Summary of Test Method4.1 Acoustic velocity meter(AVM)systems,also known asultrasonic velocity meter(UVM)systems,operate on theprinciple that the point-to-point upstream traveltime of anacoustic pulse is longer than the downstream traveltime andthat this difference in travel time can be accurately measuredby electronic devices.1This test method is 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 Jan.1,2013.Published January 2013.Originallyapproved in 1993.Last previous edition approved in 2007 as D5389 93(2007).DOI:10.1520/D5389-93R13.2For 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 standards Document Summary page onthe ASTM website.3Available 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 States1 4.2 Most commercial AVM systems that measure stream-flow use the time-of-travel method to determine velocity alongan acoustic path set diagonal to the flow.This test method4describes the general formula for determining line velocitydefined as(Fig.1 and Fig.2):VL5B2cosF1tCA21tACG(1)where:VL=line velocity,or the average water velocity at thedepth of the acoustic path,=angle of departure between streamflow and the acous-tic path,tAC=traveltime from A to C(upstream),tCA=traveltime from C to A(downstream),andB=length of the acoustic path from A to C.4.3 The discharge measurement or volume flow rate deter-mination made with an AVM relies on a calibrated or theoreti-cal relation between the line velocity as measured by the AVMand mean velocity in the flow segment being measured.Takingmore line velocity measurements across the channel at differ