BS EN ISO 6817-1993 Measurement of conductive liquid flow in closed conduits - Method using electromagnetic flowmeters《封闭管道中导电液体流量计量 电磁流量计测量法》.pdf

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1、BRITISH STANDARD BS EN ISO 6817:1997 BS 5792-1:1993 renumbered, incorporating Amendment No. 1 Measurement of conductive liquid flow in closed conduits Method using electromagnetic flowmeters The European Standard EN ISO 6817:1995 has the status of a British Standard ICS 17.120.10BSEN ISO 6817:1996 T

2、his British Standard, having been prepared under the directionof the Industrial-process Measurement and Control Standards Policy Committee, waspublished underthe authorityof the Standards Boardand comes intoeffect on 15 March 1993 BSI 03-1999 The following BSI references relate to the work on this s

3、tandard: Committee reference PCL/2 Draft for comment 92/29124 DC ISBN 0 580 22041 9 Committees responsible for this British Standard The preparation of this British Standard was entrusted by the Industrial-process Measurement and Control Standards Policy Committee (PCL/-) to Technical Committee PCL/

4、2, upon which the following bodies were represented: British Compressed Air Society British Gas plc Department of Trade and Industry (Gas and Oil Measurement Branch) Department of Trade and Industry (National Engineering Laboratory) Electricity Association Energy Industries Council Engineering Equip

5、ment and Materials Users Association GAMBICA (BEAMA Ltd.) Institute of Measurement and Control Institute of Petroleum Institute of Trading Standards Administration Institution of Gas Engineers Institution of Mechanical Engineers Society of British Gas Industries Water Research Centre Water Services

6、Association of England and Wales The following body was also represented in the drafting of the standard, through subcommittees and panels: AEA Technology Amendments issued since publication Amd. No. Date Comments 9333 January 1997 Indicated by a sideline in the marginBSEN ISO 6817:1997 BSI 03-1999

7、i Contents Page Committees responsible Inside front cover National foreword ii Foreword to EN ISO 6817 2 1 Scope 3 2 Normative references 3 3 Definitions 3 4 Symbols and units 4 5 Theorectical requirements 4 6 Construction and principle of operation 5 7 Installation design and practice 9 8 Equipment

8、 marking 13 9 Calibration and test conditions 14 10 Uncertainty analysis 14 Annex A (informative) Materials for construction of primary devices 18 Annex B (informative) Bibliography 19 Annex ZA (normative) Normative references to international publications with their relevant European publication 20

9、 Figure 1 Principle of an electromagnetic flowmeter 5 Figure 2 Elements of an industrial electromagnetic flowmeter 6 Figure 3 Exploded view of the primary device of an electromagnetic flowmeter 7 Figure 4 Principle of pulsed d.c. (bipolar) system 9 Figure 5 Shallow taper entry and exit reducers 11 F

10、igure 6 Cathodically protected pipelines: conductive links across flange joints 12 Figure 7 Typical accuracy envelopes 15 List of references Inside back coverBSEN ISO 6817:1997 ii BSI 03-1999 National foreword This Part of BS 5792 has been prepared under the direction of the Industrial-process Measu

11、rement and Control Standards Policy Committee. It is identical with ISO6817:1992 Measurement of conductive liquid flow in closed circuits Method using electromagnetic flowmeters, published by the International Organization for Standardization (ISO). It supersedes BS5792:1980 which is now withdrawn.

12、This standard now forms Part 1 of two Parts of BS5792 on electromagnetic flowmeters as follows: Part 1: Method using electromagnetic flowmeters; Part 2: Installation dimensions of flanged type electromagnetic flowmeters. In 1995 the European Committee for Standardization (CEN) accepted ISO6817:1992

13、as European Standard EN ISO6817:1995. As a consequence of implementing the European Standard this British Standard is renumbered as BSENISO6817 and any reference to BS5792-1:1993 should be read as a reference to BSENISO6817. Cross-references International standard Corresponding British Standard ISO

14、4006:1991 BS 5875:1991 Glossary of terms and symbols for measurements of fluid flow in closed conduits (Identical) ISO 5168:1978 BS 5844:1980 Methods of measurement of fluid flow: estimation of uncertainty of a flow-rate measurement (Identical) BS 7118 Measurements of a fluid flow: assessment of unc

15、ertainty in the calibration and use of flow measurement devices ISO 7066-1:1989 Part 1:1990 Linear calibration relationships (Identical) ISO 7066-2:1988 Part 2:1989 Non-linear calibration relationships (Identical) ISO 9104:1991 BS 7526:1991 Methods of evaluating the performance of electromagnetic fl

16、owmeters (Identical) Informative reference is also made to the following standards: ISO 4185:1980 BS 6199 Measurement of liquid flow in closed conduits using weighing and volumetric methods Part 1:1981 Weighing method (Identical) ISO 7194:1983 BS 1042: Measurement of fluid flow in closed conduits Se

17、ction 2.3:1984 Methods of flow measurement in swirling or asymmetric flow conditions in circular ducts by means of current-meters or Pitot static tubes (Identical) ISO 8316:1987 BS 6199 Measurement of liquid flow in closed conduits using weighing and volumetric methods Part 2:1988 Method for measure

18、ment by collection of the liquid in a volumetric tank (Identical)BSEN ISO 6817:1997 BSI 03-1999 iii A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard

19、does not of itself confer immunity from legal obligations. International standard Corresponding British Standard IEC 359:1987 BS 4889:1990 Method for specifying the performance of electrical and electronic measuring equipment (Technically equivalent) BS 5863 Analogue signals for process control syst

20、ems IEC 381-1:1982 Part 1:1984 Specification for direct current signals (Identical) IEC 381-2:1978 Part 2:1980 Specification for direct voltage signals (Identical) Summary of pages This document comprises a front cover, an inside front cover, pages i to iv, theENISOtitle page, pages 2 to 20, an insi

21、de back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on theinside front cover.iv blankEUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN ISO 6817 September 1995 ICS 17.120.10 Desc

22、riptors: Liquid flow, pipe flow, flow measurements, flowmeters, electromagnetic equipments, installation, specifications, marking English version Measurement of conductive liquid flow in closed conduits Method using electromagnetic flowmeters (ISO 6817:1992) Mesure de dbit dun fluide conducteur dans

23、 les conduites fermes Mthode par dbitmtres lectromagntiques (ISO 6817:1992) Durchflumessung von leitfhigen Flssigkeiten in geschlossenen Leitungen Verfahren mit magnetisch-induktiven Durchflumegerten (ISO 6817:1992) This European Standard was approved by CEN on1995-08-31. CEN members are bound to co

24、mply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the Central S

25、ecretariat or to any CEN member. This European Standard exists in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as the o

26、fficial versions. CEN members are the national standards bodies of Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom. CEN European Committee for Standardization Comit Europen

27、de Normalisation Europisches Komitee fr Normung Central Secretariat: rue de Stassart 36, B-1050 Brussels 1995 All rights of reproduction and communication in any form and by any means reserved in all countries to CEN and its members Ref. No. EN ISO 6817:1995 EENISO 6817:1995 BSI 03-1999 2 Foreword T

28、his European Standard was taken over by CEN from the work of ISO/TC30, Measurement of fluid flow in closed conduits, of the International Standards Organization (ISO). This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsemen

29、t, at the latest by March1996, and conflicting national standards shall be withdrawn at the latest by March1996. According to the CEN/CENELEC Internal Regulations, the following countries are bound to implement this European Standard: Austria, Belgium, Denmark, Finland, France, Germany, Greece, Icel

30、and, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and the United Kingdom.ISO 6817:1992(E) BSI 03-1999 3 1 Scope This International Standard describes the principle and main design features of industrial electromagnetic flowmeters for the measurement of flow-r

31、ate of a conductive liquid in a closed conduit running full. It covers their installation, operation, performance and calibration. This International Standard does not specify safety requirements in relation to hazardous environmental usage of the meter, nor does it apply to the measurement of magne

32、tically permeable slurries, liquid metals nor usage in medical applications. This International Standard covers flowmeter types in both a.c. and pulsed d.c. versions. 2 Normative references The following standards contain provisions which, through reference in this text, constitute provisions of thi

33、s International Standard. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this International Standard are encouraged to investigate the possibility of applying the most recent editions of the standards indicated

34、 below. Members of IEC and ISO maintain registers of currently valid International Standards. ISO 4006:1991, Measurement of fluid flow in closed conduits Vocabulary and symbols. ISO 5168:1978, Measurement of fluid flow Estimation of uncertainty of a flow-rate measurement. ISO 7066-1:1989, Assessment

35、 of uncertainty in the calibration and use of flow measurement devices Part 1: Linear calibration relationships. ISO 7066-2:1988, Assessment of uncertainty in the calibration and use of flow measurement devices Part 2: Non-linear calibration relationships. ISO 9104:1991, Measurement of fluid flow in

36、 closed conduits Methods of evaluating the performance of electromagnetic flow-meters for liquids. 3 Definitions For the purposes of this International Standard, the definitions given in ISO4006 and the following definitions apply. Many of these are extracted from ISO4006 for ease of reference. 3.1

37、electromagnetic flowmeter Flowmeter which creates a magnetic field perpendicular to the flow, so enabling the flow-rate to be deduced from the induced electromotive force (e.m.f.) produced by the motion of a conducting liquid 1)in the magnetic field. The electromagnetic flowmeter consists of a prima

38、ry device and one or more secondary devices. 3.1.1 primary device device containing the following elements: an electrically insulated meter tube through which the conductive liquid to be metered flows, one or more pairs of electrodes, diametrically opposed, across which the signal generated in the l

39、iquid is measured, an electromagnet for producing a magnetic field in the meter tube. the primary device develops a signal proportional to the flow-rate and in some cases the reference signal 3.1.2 secondary device equipment which contains the circuitry which extracts the flow signal from the electr

40、ode signal and converts it to a standard output signal directly proportional to flow-rate. This equipment may be mounted on the primary device 3.2 meter tube pipe section of the primary device through which the liquid to be measured flows; its inner surface is usually electrically insulated 3.3 mete

41、r electrodes one or more pairs of contacts by means of which the induced voltage is detected 3.4 magnetic field magnetic flux, generated by the electromagnet in the primary device, which passes through the meter tube and through the liquid 1) In the present International Standard, for electromagneti

42、c flowmeters, the more correct term “liquid” replaces the word “fluid” (covering liquids and gases) of the general definition in ISO4006. This usage also aligns with that in ISO9104.ISO 6817:1992(E) 4 BSI 03-1999 3.5 electrode signal Total potential difference between the electrodes, consisting of t

43、he flow signal and the signals not related to flow such as in-phase, quadrature and common mode voltages. 3.5.1 flow signal that part of the electrode signal which is proportional to the flow-rate and the magnetic field strength and which is dependent on the geometry of the meter tube and the electr

44、odes 3.5.2 in-phase voltage that part of the electrode signal in phase with the flow signal but which does not vary with the flowrate NOTE 1This definition applies only to primary devices with a.c.-energized electromagnets. 3.5.3 quadrature voltage that part of the electrode signal which is 90 out o

45、f phase with the flow signal and which does not vary with the flow-rate 3.5.4 common mode voltage voltage which exists equally between each electrode and a reference potential 3.6 reference signal signal, proportional to the magnetic flux created in the primary device, which is compared in the secon

46、dary device with the flow signal 3.7 output signal output from the secondary device which is a function of the flow-rate 3.8 calibration factor of the primary device a number which enables the flow signal to be related to the volume flow-rate (or average velocity) under defined reference conditions

47、for a given value of the reference signal 3.9 full-scale flowrate flow-rate corresponding to the maximum output signal 3.10 cathodic protection electrochemical means of preventing electrolytic corrosion of conduits 3.11 reference conditions conditions for calibration of a flowmeter in accordance wit

48、h clause8 of this International Standard 4 Symbols and units The following symbols are used in this International Standard. 5 Theoretical requirements 5.1 General When a liquid moves in a magnetic field, voltages (e.m.f.s) are generated in accordance with Faradays law (see Figure 1). If the field is

49、 perpendicular to an electrically-insulated pipe which contains the moving liquid and if the electrical conductivity of the liquid is not too low, a voltage may be measured between two electrodes on the wall of the pipe. This voltage is proportional to the magnetic flux density, the average velocity of the liquid and the distance between the electrodes. Thus the velocity and hence the flow-rate of the liquid may be measured. Symbol Quantity Units B D K L e U V k q v Magnetic flux density Inside diameter of meter