BS 3680-8H-1996 Measurement of liquid flow in open channels - Measuring instruments and equipment - Method of specifying the performance of hydrometric equipment《明渠流量测量 第8H部分 测量仪器和.pdf

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1、BRITISH STANDARD BS3680-8H: 1996 ISO11655: 1995 Measurement of liquid flow in open channels Part 8: Measuring instruments and equipment Part 8H: Method of specifying the performance of hydrometric equipmentBS3680-8H:1996 This British Standard, having been prepared under the direction of the Electrot

2、echnical Sector Board, was published under the authority of the Standards Board and comes into effect on 15 January1996 BSI 08-1999 The following BSI references relate to the work on this standard: Committee reference CPL/113 Draft for comment92/03263 DC ISBN0 580 25226 4 Committees responsible for

3、this British Standard The preparation of this British Standard was entrusted to Technical Committee CPL/113, Flow measurement of surface and ground water, upon which the following bodies were represented: British Waterways Board Clyde River Purification Board Department of the Environment (Water Dir

4、ectorate) Institute of Measurement and Control Institution of Civil Engineers Institution of Water and Environmental Management National Rivers Authority Water Services Association of England and Wales The following bodies were also represented in the drafting of the standard through subcommittees a

5、nd panels: British Hydrological Society GAMBICA Water Research Centre Amendments issued since publication Amd. No. Date CommentsBS3680-8H:1996 BSI 08-1999 i Contents Page Committees responsible Inside front cover National foreword ii Introduction 1 1 Scope 1 2 Normative references 2 3 Definitions 2

6、4 Units of measurement 3 5 Objectives 3 6 Equipment performance 3 7 Overall equipment performance 4 8 Data output formats 5 9 Energy requirement 5 10 User requirements 5 Annex A (informative) Recommended checklist 6 List of references Inside back coverBS3680-8H:1996 ii BSI 08-1999 National foreword

7、This Part of BS3680 has been prepared by Technical Committee CPL/113 and is identical with ISO11655:1995 Measurement of liquid flow in open channels Method of specifying performance of hydrometric equipment, published by the International Organization for Standardization (ISO). Other standards withi

8、n the BS3680-8 series on measuring instruments and equipment are as follows: Part8A: Current meters incorporating a rotating element; Part8B: Recommendations for direct depth sounding and suspension equipment; Part8C: Calibration of rotating-element current-meters in straight open tanks; Part8D: Cab

9、leway systems for stream gauging; Part8F: Hydrometric data transmission systems: general; Part8G: Specification for system requirements for hydrometric telemetry systems. Cross-reference. The Technical Committee has reviewed the provisions of ISO772:1988 to which normative reference is made in the t

10、ext and has decided that it is suitable for use in conjunction with this British Standard. A related British Standard is BS3680 Measurement of liquid flow in open channels Part1:1991 Glossary of terms. A British Standard does not purport to include all the necessary provisions of a contract. Users o

11、f British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages1 to 8, an inside back cover and a back

12、 cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.BS3680-8H:1996 BSI 08-1999 1 Introduction This International Standard contains recommendations for a method of specifying the

13、performance of equipment used for the sensing, measuring and, as appropriate, recording of physical variables related to measurement of liquid flow in open channels. The process of sensing, measuring and recording hydrological phenomena requires the conversion of a time-related physical event or sta

14、te into a numerical expression in terms relative to a standard scale of measurement units. The steps in the conversion are the following: a) adaptation or conversion (as the individual situation requires) of the naturally occurring phenomenon into a state where a representative determination can be

15、made; b) if necessary, identification of a surrogate parameter and the establishment of the relation between changes in that parameter value and changes in the phenomenon to be measured; c) sensing, measurement and (if appropriate) recording of the physical phenomenon or its surrogate as it varies w

16、ith the passage of time; d) conversion of sampled data into numerical information. The ultimate measure of equipment performance is the evaluation of the uncertainty with which the equipment converts the absolute value or level of the hydrological variable into a measured quantity, relative to anoth

17、er arbitrary or fixed reference datum. The suitability of a piece of equipment, however, may also be related to the particular method of measurement and to the measurement frequency. The nature of the uncertainty is closely related to the physical method or principle employed in the process of conve

18、rsion from the natural variable to the measured quantity. Different physical systems are affected to differing degrees by such factors as: intrinsic design of the equipment; calibration methods; natural environmental factors; man-made environmental factors; levels of care and maintenance; operator m

19、ethods and skills. The user should seek to identify the three fundamental factors which may affect the uncertainty; these, which should be objectively defined from study of the method of measurement, are: a) the level of uncertainty of each individual measurement due to the principle of operation of

20、 the measurement equipment; b) the range of factors, for example environmental conditions (expressed numerically) and other external forces which influence the performance of the measurement equipment; c) the frequency with which the hydrological variable should be sampled by the equipment in order

21、to achieve the required level of data uncertainty. The previous information represents the minimum which must be made available to the manufacturer before he can recommend a product or commence design and manufacture. Taken together these factors describe the customer specifications for the performa

22、nce of the measurement equipment. Once a design is selected for the equipment, the specifications for use are established through the relevant standards documentation on methods of measurement. Levels of care and maintenance are laid down by the manufacturer in the equipment handbook, and should be

23、adhered to if the manufacturers claims of performance levels are to be achieved and maintained. If followed by the manufacturer, this method will provide the user with a basis for understanding the ability of a particular piece of equipment to meet the purpose intended. It further provides a framewo

24、rk within which the user may specify his requirements to the manufacturer and against which he may judge the usefulness of a product. 1 Scope This International Standard provides a method of specifying the performance of hydrometric equipment. It identifies, within a performance framework, the facto

25、rs that affect the range of uncertainty within which the hydrological quantity is converted into a numerical quantity.BS3680-8H:1996 2 BSI 08-1999 This International Standard applies to all equipment used for hydrological measurement, with the exception of equipment used for the determination of wat

26、er quality. The sensor, the measurement system and the recorder are treated as a unit, whether operated in mechanical, electromechanical or electronic form, or using other physical principles. Because hydrological variables are frequently determined against time, the time measurement device is also

27、considered to be an integral part of the measurement system. 2 Normative references The following standards contain provisions which, through reference in this text, constitute provisions of this International Standard. At the time of publication, the editions indicated were valid. All standards are

28、 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 below. Members of IEC and ISO maintain registers of currently valid International Standards. ISO31-1:1992

29、, Quantities and units Part1:Space and time. ISO 31-3:1992, Quantities and units Part3:Mechanics. ISO 772:, Measurement of liquid flow in open channels Vocabulary and symbols 1) . 3 Definitions For the purposes of this International Standard, the definitions given in ISO772 and the following definit

30、ions apply. 3.1 influencing factor condition (environmental or otherwise), element, or activity external to the measuring equipment which may influence equipment performance 3.2 performance measure degree to which the intended functions of the equipment are accomplished 3.3 range span of values of t

31、he quantity being measured or of an influencing factor 3.4 conditions of storage and transport those conditions specified by the manufacturer under which equipment may be stored and transported in an inoperative state and may be subjected to influences outside those experienced in use or operation u

32、nder these conditions the equipment may be specially packed or protected in whatever way considered appropriate by the manufacturer, in order that the equipment should not suffer damage or degradation of performance when subsequently operated within the applicable range of conditions 3.5 conditions

33、for normal operation those conditions within which the equipment is expected to measure the parameter under study in accordance with the appropriate criteria of performance the range of operational conditions shall be defined by the user 3.6 extreme conditions of equipment use those conditions which

34、 exceptionally lie outside the range normally applicable to equipment operation, and against which the equipment is provided with no special protection the equipment is expected to resume required performance levels as soon as the influencing factors return to within the range applicable to the oper

35、ation mode. The limits of these conditions should be specified by the manufacturer 3.7 hazardous area area in which exist hazardous conditions potentially capable of endangering safety by whatever means the danger may arise through physical location or through exposure to a potentially explosive atm

36、osphere, for example in sewers 3.8 overall performance level statement of expected performance of the equipment, relative to the true values of the measured hydrological variable 3.9 timing performance statement of expected performance of any timing element of the equipment employed to control the s

37、ampling rate or frequency 1) To be published. (Revision of ISO772:1988)BS3680-8H:1996 BSI 08-1999 3 4 Units of measurement The units of measurement used in this International Standard are SI units, in accordance with ISO31-1 and ISO31-3. 5 Objectives The purposes of this International Standard are t

38、o specify the terminology and definitions related to the functional performance of equipment used for the determination of hydrological data and information, to specify the requirements for statements by manufacturers, and to recommend the criteria to be identified by users/customers at the time of

39、ordering/acquiring equipment for hydrological measurement purposes. 6 Equipment performance 6.1 Influencing factors Before choosing equipment for measurement purposes, the user should ascertain that the equipment will provide the required operational performance relative to the chosen method of meas

40、urement under the range of factors which may influence that performance. These influencing factors are as follows. 6.1.1 Atmospheric conditions a) Ambient temperature; b) atmospheric humidity; c) atmospheric pressure; d) atmospheric quality (for example atmospheric contaminants); e) atmospheric prec

41、ipitation; f) solar radiation; g) wind speed; h) environmental electrical discharges (natural and man-made); i) electromagnetic interference. 6.1.2 Aquatic conditions a) Water temperature; b) water pressure; c) water quality (for example pH, suspended solids, conductivity, visible oil). 6.1.3 Mechan

42、ical factors a) Operating position; b) vibration; c) mechanical shock. 6.1.4 Other factors a) Nature of energy source; b) level of biological activity; c) electrical interference through ground or water; d) operator skill; e) standards of operational maintenance. 6.2 Range of values of influencing f

43、actors Manufacturers supplying equipment for hydrometric measurement purposes, either as complete measurement systems or as elements of such systems, shall provide statements of the limiting ranges of values for each of the influencing factors listed inAnnex A,A.1 toA.3. Annex A presents three equip

44、ment situations for which ranges of influencing factors shall be provided: a) equipment storage and transport, when the equipment is in an inoperative state; b) equipment use when required to produce a functional signal only; c) equipment operation when required to produce data within the performanc

45、e limits declared by the manufacturer and in accordance with the requirements ofclause7. Equipment operating in accordance with this International Standard shall show no permanent damage or degradation of performance when, whether inoperative or in use, it is subjected to conditions where one or mor

46、e of the influencing factors assumes a value within the limiting values of any of the ranges assigned for the equipment during a specified time. If no time limit is specified, it should be assumed that such conditions apply for an indefinite time. On re-establishment of conditions in which values of

47、 the influencing factors lie within the operating range, the equipment is expected to operate within the stated performance limits. It is recommended that the user and the manufacturer use the checklist form inAnnex A, in order to clearly identify all environmental and other influencing factors whic

48、h may affect equipment performance. It is further recommended that there be discussion between the manufacturer and the user in order to identify any combination of factors that may result in abnormal effects.BS3680-8H:1996 4 BSI 08-1999 7 Overall equipment performance 7.1 General The user shall sta

49、te the allowable tolerance on any single parameter/measurement which lies within the operational range, subject to all influencing factor values lying within the range of operational use. The allowable tolerance may vary from one part of the range to another, in which case the user shall state both allowable tolerance values and the subdivision of the operational range over which any specific tolerance value applies. The manufacturer shall state the performance characteristics of the equipment over the full operational range required