ASTM_D_4409_-_95_2014.pdf

Designation:D440995(Reapproved 2014)Standard Test Method forVelocity Measurements of Water in Open Channels withRotating Element Current Meters1This standard is issued under the fixed designation D4409;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 describes the design and use ofcup-type or vane-type vertical axis current meters andpropeller-type horizontal axis current meters for measuringwater velocities in open channels.1.2 This test method is intended primarily for those meterscustomarily used in open-channel hydraulic(as distinguishedfrom oceanographic)applications with an operator in atten-dance.1.3 This test method is intended primarily for current metersthat measure one component or filament of flow.1.4 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.1.5 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.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 Standards:3ISO 2537 Liquid Flow Measurement in Open ChannelsRotating Element Current MetersISO 3454 Liquid Flow Measurement in Open ChannelsDirect Depth Sounding and Suspension EquipmentISO 3455 Liquid Flow Measurement in Open ChannelsCalibration of Rotating-Element Current Meters inStraight Open Tanks3.Terminology3.1 DefinitionsFor definitions of other terms used in thistest method,refer to Terminology D1129.3.2 Definitions of Terms Specific to This Standard:3.2.1 current meteran instrument used to measure thespeed or velocity of flowing water at a point.3.2.2 Price-type current metersgeneric name for specificvertical axis meters with a rotating element consisting of sixconical cups and constructed as described in Refs(1-3).43.2.3 spin testa test performed to check the bearings of acurrent meter.This test is used primarily with vertical axiscurrent meters.3.2.4 turbulenceirregular condition of flow in which thevelocity exhibits a random variation with time and spacecoordinates so that statistically distinct average values can bediscerned.4.Summary of Test Method4.1 The angular velocity of the rotating element is afunction of water speed at the point of immersion.This angularvelocity is determined from the meter output and its functionalrelation to the water speed is determined by calibration.5.Significance and Use5.1 This test method describes the design and use of varioustypes of current meters.These current meters are commonlyused to measure the velocity at a point in an open channel crosssection as part of a velocity-area traverse to determine theflowrate of water.To this end it should be used in conjunctionwith Test Method D3858.1This 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.1,2014.Published March 2014.Originallyapproved in 1984.Last previous edition approved in 2008 as D4409 95(2008).DOI:10.1520/D4409-95R14.2For 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.4The boldface numbers refer to the list of references at the end of this testmethod.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 6.Interferences6.1 As with any intrusive flow measuring device,rotatingelement current meters are subject to damage by debris,especially in high velocity flows,and to fouling by floatingmaterials such as aquatic growths and sewage.6.2 Owing to bearing friction,each rotating element currentmeter has a limiting low velocity below which it does notfunction reliably.This velocity is different for each type ofmeter but,in general,%errors tend to become large as thevelocities decrease below 0.1 to 0.2 ft/s(0.03 to 0.06 m/s).7.Apparatus7.1 Current MetersRotating element current meters con-sist of a rotating element with shaft and bearings,a mechanismfor detecting and registering rev