1、AN AMERICAN NATIONAL STANDARD ASME MFC-5.32013Measurement of Liquid Flow in Closed Conduits Using Doppler Ultrasonic FlowmetersASME MFC-5.32013Measurement ofLiquid Flow in ClosedConduits UsingDoppler UltrasonicFlowmetersAN AMERICAN NATIONAL STANDARDTwo Park Avenue New York, NY 10016 USADate of Issua
2、nce: July 19, 2013This Standard will be revised when the Society approves the issuance of a new edition.ASME issues written replies to inquiries concerning interpretations of technical aspects of thisStandard. Periodically certain actions of the ASME MFC Committee may be published as Cases.Cases and
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11、permission of the publisher.The American Society of Mechanical EngineersTwo Park Avenue, New York, NY 10016-5990Copyright 2013 byTHE AMERICAN SOCIETY OF MECHANICAL ENGINEERSAll rights reservedPrinted in U.S.A.CONTENTSForeword ivCommittee Roster . vCorrespondence With the MFC Committee . vi1 General
12、. 12 Principle of Operation . 23 Uncertainty Sources and Uncertainty Reduction . 64 Application and Selection 115 Calibration and Diagnostics 12Figures2.1-1 Doppler Phenomena Without a Scatterer 32.1-2 Doppler Phenomena With a Scatterer . 42.1-3 Doppler Beam Not Parallel to the Flow Direction . 42.1
13、-4 Clamp-On Doppler . 52.2-1 Scatterer Moving Perpendicular to a Transducer . 62.3-1 Doppler Measurement Systems . 73.2.2-1 A Typical Cross-Path Ultrasonic Flowmeter Configuration . 93.2.3-1 Measurement Volume Location and Flow Profile Averaging . 103.2.3-2 Uncertainty in Penetration Depth Due to Pi
14、pe Wall Reflections 10Tables1.3-1 Symbols . 21.3-2 Subscripts 2iiiFOREWORDThe need for a document describing measurement of liquid flows by means of ultrasonicflowmeters has been recognized for many years. The ASME Committee on Measurement of FluidFlow in Closed Conduits (MFC) and its Subcommittee 5
15、: Ultrasonic Flowmeters (SC 5) haveagreed to publish three standards to assist the users in understanding the three technologies:transit time, cross-correlation, and scattering (Doppler).Published in June 2011, ASME MFC-5.1, Measurement of Liquid Flow in Closed Conduits UsingTransit-Time Ultrasonic
16、Flowmeters, applies to ultrasonic flowmeters that base their operation onthe measurement of transit time of acoustic signals. MFC-5.1 concerns the volume flow-ratemeasurement of a single-phase liquid with steady flow or flow varying only slowly with timein a completely filled closed conduit.This Sta
17、ndard, Measurement of Liquid Flow in Closed Conduits Using Doppler UltrasonicFlowmeters, applies to ultrasonic flowmeters that base their operation on the reflection of waves.It concerns the volume flow-rate measurement of a liquid dominant fluid with steady flow orflow varying only slowly with time
18、 in a completely filled closed conduit.Suggestions for improvement of this Standard are welcome. They should be addressed to theSecretary, ASME MFC Standards Committee, Two Park Avenue, New York, NY 10016-5990.This Standard was approved as an American National Standard on April 12, 2013.ivASME MFC C
19、OMMITTEEMeasurement of Fluid Flow in Closed Conduits(The following is the roster of the Committee at the time of approval of this Standard.)STANDARDS COMMITTEE OFFICERSR. J. DeBoom, ChairD. C. Wyatt, Vice ChairC. J. Gomez, SecretarySTANDARDS COMMITTEE PERSONNELC. J. Blechinger, Honorary Member, Cons
20、ultantR. M. Bough, Rolls-Royce Corp.M. S. Carter, Flow Systems, Inc.R. J. DeBoom, ConsultantD. Faber, Contributing Member, Badger Meter, Inc.C. J. Gomez, The American Society of Mechanical EngineersF. D. Goodson, Emerson Process Management Daniel DivisionZ. D. Husain, Chevron Corp.C. G. Langford, Ho
21、norary Member, ConsultantW. M. Mattar, Invensys/Foxboro Co.SUBCOMMITTEE 5: ULTRASONIC FLOWMETERSR. J. DeBoom, Chair, ConsultantR. Schaefer, Vice Chair, Siemens Industry, Inc.X. S. Ao, GED. R. Augenstein, CameronP. G. Espina, Flowbusters, Inc.R. H. Fritz, Regency Gas ServiceB. Funck, Flexim Labs, LLC
22、F. D. Goodson, Emerson Process Management Daniel DivisionH. E. Hall, Dow Chemical Canada ULCvG. E. Mattingly, ConsultantR. W. Miller, Honorary Member, R. W. Miller however, they shouldnot contain proprietary names or information.Requests that are not in this format may be rewritten in the appropriat
23、e format by the Committeeprior to being answered, which may inadvertently change the intent of the original request.ASME procedures provide for reconsideration of any interpretation when or if additionalinformation that might affect an interpretation is available. Further, persons aggrieved by anint
24、erpretation may appeal to the cognizant ASME Committee or Subcommittee. ASME does not“approve,” “certify,” “rate,” or “endorse” any item, construction, proprietary device, or activity.Attending Committee Meetings. The MFC Standards Committee regularly holds meetings thatare open to the public. Perso
25、ns wishing to attend any meeting should contact the Secretary ofthe MFC Standards Committee.viASME MFC-5.32013MEASUREMENT OF LIQUID FLOW IN CLOSED CONDUITS USINGDOPPLER ULTRASONIC FLOWMETERS1 GENERAL1.1 ScopeThis Standard applies only to ultrasonic flowmetersthat base their operation on the reflecti
26、on of acousticwaves, frequently referred to as a Doppler flowmeter.The flow measurement utilizes either frequency or timedomain techniques. This Standard concerns the volumeflow-rate measurement of a liquid dominant fluid withsteady flow or flow varying only slowly with time in acompletely filled cl
27、osed conduit.1.2 PurposeThis Standard provides a(a) description of the operating principles employedby the ultrasonic flowmeters covered in this Standard(b) guideline to expected performance characteristicsof ultrasonic flowmeters covered in this Standard(c) description of calibration and diagnostic
28、procedures(d) description of potential uncertainty sources andtheir reduction(e) common set of terminology, symbols, definitions,and specifications1.3 Terminology and SymbolsParagraph 1.3.1 lists definitions from ASME MFC-1Mused in this Standard. Paragraph 1.3.2 lists definitionsspecific to this Sta
29、ndard. Table 1.3-1 lists symbols usedin this Standard. Table 1.3-2 lists subscripts used in thisStandard.1.3.1 Definitions From ASME MFC-1Maccuracy: the degree of freedom from error; the degreeof conformity of the indicated value to the true valueof the measured quantity.NOTES:(1) The concept measur
30、ement accuracy is not a quantity and is notgiven a numerical quantity value. A measurement is said to bemore accurate when it provides a smaller measurement error.(2) The term measurement accuracy is sometimes understood ascloseness of agreement between measured quantity values that arebeing attribu
31、ted to the measured. Measurement accuracy shouldnot be mistaken for measurement precision.axial flow velocity: the component of liquid flow velocityat a point in the measurement section that is parallel to1the measurement sections axis and in the direction ofthe flow being measured.calibration: the
32、experimental determination of the rela-tionship between the quantity being measured and thedevice that measures it, usually by comparison with atraceable reference standard. Also, the act of adjustingthe output of a device to bring it to a desired value,within a specified tolerance, for a particular
33、 value of theinput.NOTE: This document is written with calibration defined as thedetermination of difference from a reference and the adjustmentto align within a specified tolerance. This is common U.S. usage.It is understood that in other parts of the world, some countriesand groups define calibrat
34、ion as only the determination of differ-ence from a reference. A second term used is calibration adjust-ment, which is to align within a specified tolerance.cross-flow velocity: component of liquid flow velocity ata point in the measurement section that is perpendicularto the measurement sections ax
35、is.nonrefractive system: an ultrasonic flowmeter in whichthe acoustic path crosses the solid/process liquid inter-faces at a right angle.refractive system: an ultrasonic flowmeter in which theacoustic path crosses the solid/process liquid interfacesat other than a right angle.uncertainty: the range
36、within which the true value of themeasured quantity can be expected to lie with a specifiedprobability and confidence level.velocity profile correction factor, S: dimensionless factorbased on measured knowledge of the velocity profileused to adjust the meter output.1.3.2 Definitions Specific to This
37、 Standarddiagnostics: comparison of internal direct and derivedmeasurement values to allow the user to ascertain thecondition of the operation of the ultrasonic flowmeter.measurementsection: section of conduit in which the volu-metric flow rate is sensed by the acoustic signals. Themeasurement secti
38、on is bounded at both ends by planesperpendicular to the axis of the section and located atthe extreme upstream and downstream transducer posi-tions. The measurement section is usually circular incross section; however, it may be square, rectangular,elliptical, or some other shape.ASME MFC-5.32013Ta
39、ble 1.3-1 SymbolsQuantity (First Location) Symbol Dimensions SI UnitsCross-sectional area AL2m2Sound propagation speed eq. (1) cLT1m/sFrequency fT1HzDistance between transmitter/receiver and scatterer lLmVolume flow rate QL3T1m3/sVelocity profile correction factor S . .Time tTsVelocity of wave sourc
40、e (Fig. 2.1-1) H9263wsLT1m/sFlow velocity H9263 LT1m/sAverage velocity H9263xLT1m/sMean axial velocity H9263LT1m/sVelocity of a scatterer (Fig. 2.1-2) H9263sLT1m/sDoppler shifted frequency eq. (1) f T1HzDoppler frequency shift H9004fT1HzSource frequency (carrier frequency) eq. (1) f0T1HzTransducer t
41、ransmit signal eq. (9) st(t) . .Transducer receive signal eq. (9) sr(t). .Round-trip time eq. (9) trtT sDelta round-trip time eq. (13) H9004trtT sTime difference between successive transmissions H9004tpT sWeighting factor for acoustical path w . .Angle between the pipe wall and direction of H9272 .
42、radacoustic propagationmeasurement volume: region within the measurement sec-tion from which acoustic waves reflected by scatters arereceived by the receiving transducer.mode conversion: when an ultrasonic wave passes at anoblique angle between two materials of variant acousticimpedance, mode conver
43、sion can occur. As an example,when a wedge-type transducer is coupled to the outsideof a pipe, the longitudinal waves generated by the ultra-sonic transducer can produce multiple other types ofwaves (e.g., shear waves) in the pipe wall.scatterer(s): discontinuity in the acoustic impedance ofthe liqu
44、id. Scatterers are suspended solids or gas bubblesthat reflect the sound in the liquid. Meter manufacturersmay call them reflectors.ultrasonictransducer: a device designed to convert electri-cal signals into directed ultrasonic waves and vice versa,usually by inclusion of materials exhibiting the pi
45、ezo-electric or piezomagnetic effects. When employed forflow measurement, ultrasonic transducers are com-monly referred to simply as transducers.1.3.3 Symbols Used in This Standard. SeeTable 1.3-1.1.3.4 Subscripts Used in This Standard. SeeTable 1.3-2.2 PRINCIPLE OF OPERATIONThe ultrasonic flowmeter
46、 can be thought of as com-prising a primary and secondary device. The primary2Table 1.3-2 SubscriptsSubscriptSymbol Descriptionx Direction corresponding to the pipe axisy Direction orthogonal to the pipe axis andin the plane formed by the acoustic beamand pipe axiss Scatterer velocityrt Round-tripws
47、 Wave sourcedevice consists of a measurement section with theinstalled transducers. The measurement section may bea whole spool piece or an existing section of pipe towhich transducers are installed.The secondary device comprises the electronic equip-ment required to operate the transducers, make th
48、e mea-surements, process the measured data, and display orrecord the results. The secondary processing section, inaddition to estimating the flow rate from the measure-ment, should be capable of rejecting invalid measure-ments, noise, etc. The indicated flow rate may be theresult of one or more indi
49、vidual flow velocitydeterminations.Most meters have outputs available, either as standardfeatures or as optional equipment. Displays may showflow rate, integrated flow volume, and/or direction andmay be analog or digital. Signal outputs usually includeone or more of the following: current, voltage, digital,ASME MFC-5.32013Fig. 2.1-1 Doppler Phenomena Without a ScattererAcoustic sourcevwsObserver(receiver)and a pulse rate proportional to flow. These outputsmay or may not be electrically isolated. Flowmeters mayalso include alarms and diagnostic aid
