ASTM_D_4408_-_84_scan.pdf

I ASTM DY40B BY 0757510 0035YOL b,KWERICAN SOCIETY FOR TESTING ANDMATERIALS Reprinted from the Annual Book of ASTM Standards,Copyright ASTM If not listed in the current combined index,will appear in the flext editio-1916 Race St.,Philadelphia,Pa.19103 I Standard Practice for OPEN CHANNEL FLOW MEASUREMENT BY ACOUSTIC MEANS This standard is issued under the fixed designation D 4408;the number immediately foliowing the designation indicatesfhe year of original adoption or,in the c a s e of revision,the year of last revision.A number in parentheses indicates the year of lasf reapproval.A superscript epsilon(E)indicates an editorial change since the last revision or reapproval.1.Scope I.1 This practice covers the measurement of flow rate of water in open channels,streams,and closed conduits that are not flowing full.1.2 This practice is applicable to flow rate measurement in a l l size channels and conduits.However,limitations of applications apply in some cases(see Section 6).1.3 This standard tnay involve hazardous ma-terials,operations,and equipment.This standard does not purport to address all o f the safty prob-lems associated with its use.it i s the responsibil-ity o f whoever uses this standard to consult and establish appropriate sajty and health practices and determine the applicability o f regulatory limi-tations prior to use.2.Applicable Documents 2.1 ASTMStandards:D 1129 Definitions of Terms Relating to Wate?D3857 Practice for Measurement of Water Velocity in Open Channels by Acoustic Means D 3858 Practice for Open-Channel Flow Mea-surement I r Water by Velocity-Area Method 2.2 IS0 s1,:i;:.-J.IS0 555 Liqux?Flr.w Measurement in Open Channels-Di:ut,on Methods for Measure-ment of Steady Flow-Constant Rate Injec-tion Method3 3.Terminology Standard:3.1 Descriptions o f Terms Specific to This 3.I.1 acoustic path-the straight line between the centers of two acoustic transducers.3.1.2 acoustic path length-the face-to-face distance between transducers on an acoustic path.3.1.3 acoustic transducer-a device that is used to generate acoustic signals when driven by an electric voltage,and,conversely,a device that is used to generate an electric voltage when ex-cited by an acoustic signal.3.1.4 acoustic traveltime-the time required for an acoustic signal to propagate along an acoustic path,either upstream or downstream,3.1.5 discharge-the rate of flow expressed in units of volume of water per unit of time.The discharge includes any sediment or other solids that may be dissolved or mixed with it.3.I.6 line velocitp-the downstream water ve-locity averaged over an acoustic path.3.1.7 measurement plane-the plane formed by two or more parallel acoustic paths at different elevations.3.1.8 stage-the height of a water surface above an established(or arbitrary)datum plane;also gage height.3.1.9 velocity sampling-means of obtaining line velocities in a measurement plane that are suitable for detemhing flow rate by a velocity-area intn.I This Wcti is under tbc jusisdicion of Committee D I 9 on Water and i s the directresponsibility of Subcommittee D19.03onSamplingofWaairdWater-FormedDeposits,and Surveillance of Water.Currentedition approved Oct.26,1984.PuMished February 1985.Annual Book qfASTMsiandards.Vol 11.01.Ava&bk from 1 Rue de Varembe,Case P d e 56,CH-1 2 1 1,G e n e v a 2 0,S w i .1 I-a NOTICE:This standard has either been superseded and replaced by a new version or discontinued.Contact ASTM International(www.astm.org)for the latest information.ASTM D4408 84 U 0759530 0035402 8 W 3.2 Definitions-For definitions of terms used in this practice refer to Definitions D 1129.4.Summary of Method 4.1 The discharge measurement or volume flow rate determination is made by taking one or more line velocity measurements across the channel at different elevations in the acoustic plane and performing a numerical integration or weighted summation of the measured velocities and areas of flow in order to estimate the volume flow rate.The spacing between acoustic paths,the spacing between the top path and the liquid surface,and the spacing between the lowest path and the bottom are determined on the basis of prior knowledge or estimates of the vertical-ve-locity distribution and by the required measure-ment accuracy.In addition to several line veloc-ity measurements,it is necessary to provide level(stage)information for calculation of the volume flow rate.See Fig.1.5.Significance and Use 5.1 This practice is used where high accuracy of velocity or continuous discharge measurement over a long period of time is required and other methods of measurement are not feasible due to high velocities in the channel or the presence of marine traffic.It has the additional advantages of requiring no moving parts,introducing no head loss,and providing virtually instantaneous readings(1 to 100 s per reading).5.2 The practice may require a relatively large amount of site work and survey effort and is therefore most suitable for permanent or semi-permane