BS EN ISO 4373-2008 Hydrometry - Water level measuring devices《液体比重测定法 水位测量装置》.pdf

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1、BS EN ISO4373:2008ICS 17.120.20NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBRITISH STANDARDHydrometry Waterlevel measuringdevices (ISO 4373:2008)This British Standardwas published under theauthority of the StandardsPolicy and StrategyCommittee on 3 2008 BSI 2008ISBN 978 0 5

2、80 53817 9Amendments/corrigenda issued since publicationDate CommentsBS EN ISO 4373:2008National forewordThis British Standard is the UK implementation of EN ISO 4373:2008. Itsupersedes BS 3680-7:2000 which is withdrawn.The UK participation in its preparation was entrusted to TechnicalCommittee CPI/

3、113/5, Measuring instruments and equipment.A list of organizations represented on this committee can be obtained onrequest to its secretary.This publication does not purport to include all the necessary provisionsof a contract. Users are responsible for its correct application.Compliance with a Brit

4、ish Standard cannot confer immunityfrom legal obligations.0NovemberEUROPEAN STANDARDNORME EUROPENNEEUROPISCHE NORMEN ISO 4373October 2008ICS 17.120.20English VersionHydrometry - Water level measuring devices (ISO 4373:2008)Hydromtrie - Appareils de mesure du niveau de leau (ISO4373:2008)Hydrometrie

5、- Gerte zur Wasserstandsmessung (ISO4373:2008)This European Standard was approved by CEN on 4 October 2008.CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this EuropeanStandard the status of a national standard without any alteratio

6、n. Up-to-date lists and bibliographical references concerning such nationalstandards may be obtained on application to the CEN Management Centre or to any CEN member.This European Standard exists in three official versions (English, French, German). A version in any other language made by translatio

7、nunder the responsibility of a CEN member into its own language and notified to the CEN Management Centre has the same status as theofficial versions.CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland,France, Germany, Greece

8、, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.EUROPEAN COMMITTEE FOR STANDARDIZATIONCOMIT EUROPEN DE NORMALISATIONEUROPISCHES KOMITEE FR NORMUNGManagement Cent

9、re: rue de Stassart, 36 B-1050 Brussels 2008 CEN All rights of exploitation in any form and by any means reservedworldwide for CEN national Members.Ref. No. EN ISO 4373:2008: EBS EN ISO 4373:2008EN ISO 4373:2008 (E) 3 Foreword This document (EN ISO 4373:2008) has been prepared by Technical Committee

10、 ISO/TC 113 “Hydrometric determinations“ in collaboration with Technical Committee CEN/TC 318 “Hydrometry” the secretariat of which is held by BSI. This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by

11、April 2009, and conflicting national standards shall be withdrawn at the latest by April 2009. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN and/or CENELEC shall not be held responsible for identifying any or all such patent

12、 rights. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland

13、, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom. Endorsement notice The text of ISO 4373:2008 has been approved by CEN as a EN ISO 4373:2008 without any modification. BS EN ISO 4373:2

14、008ISO 4373:2008(E) ISO 2008 All rights reserved iiiContents Page Foreword iv 1 Scope . 1 2 Normative references . 1 3 Terms and definitions. 1 4 Instrument specification 1 4.1 Performance classifications 1 4.2 General. 1 4.3 Maximum rate of change 2 4.4 Environment 2 4.5 Timing 3 5 Recording 3 5.1

15、Chart recorders . 3 5.2 Data loggers 3 6 Enclosure. 3 7 Installation . 3 8 Estimation of measurement uncertainty 4 8.1 General. 4 8.2 Type-A estimation. 4 8.3 Type-B estimation. 4 8.4 Level measurement datum 4 8.5 Combining primary measurement uncertainties. 4 Annex A (informative) Types of water le

16、vel measuring devices . 5 A.1 Reference gauges. 5 A.2 Peak level gauges. 9 A.3 Mechanical float and counterweight gauges . 10 A.4 Air reaction gauges 11 A.5 Electrical pressure transducers 14 A.6 Echo-location, acoustic instruments 15 A.7 Echo-location, radar instruments . 16 A.8 Systems using elect

17、rical properties . 17 A.9 Recording devices 18 Bibliography . 20 BS EN ISO 4373:2008ISO 4373:2008(E) iv ISO 2008 All rights reservedForeword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing Inte

18、rnational Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison wi

19、th ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main task of technic

20、al committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. Attention is drawn t

21、o the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. ISO 4373 was prepared by Technical Committee ISO/TC 113, Hydrometry, Subcommittee SC 5, Instruments, equipment and data m

22、anagement. This third edition cancels and replaces the second edition (ISO 4373:1995), which has been technically revised. BS EN ISO 4373:2008INTERNATIONAL STANDARD ISO 4373:2008(E) ISO 2008 All rights reserved 1Hydrometry Water level measuring devices 1 Scope This International Standard specifies t

23、he functional requirements of instrumentation for measuring the level of water surface (stage), primarily for the purpose of determining flow rates. This International Standard is supplemented by an annex providing guidance on the types of water level measurement devices currently available and the

24、measurement uncertainty associated with them (see Annex A). 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (i

25、ncluding any amendments) applies. ISO 772, Hydrometry Vocabulary and symbols IEC 60529, Degrees of protection provided by enclosures (IP Code) IEC 60079-10, Electrical apparatus for explosive gas atmospheres Part 10: Classification of hazardous areas 3 Terms and definitions For the purpose of this d

26、ocument, the terms and definitions given in ISO 772 apply. 4 Instrument specification 4.1 Performance classifications The parameters of performance of a water level measuring device shall be described by the classification categories of uncertainty, temperature range and relative humidity so that th

27、e overall performance of the equipment may be summarized in three digits. 4.2 General Water level measuring devices shall be classified in accordance with the performance classes given in Table 1 that account for the resolution to be achieved and the limits of uncertainty required over specified ran

28、ges. It should be made clear whether these levels of attainment can only be achieved by the use of special works, for example installation within stilling wells. It is also important to remember that in the measurement of stage, uncertainty expressed as a percentage of range gives rise to worst case

29、 uncertainty in the determination of stage at low values of stage. This is highly significant for the measurement of low flows and should be taken into account in the design of equipment for this purpose. BS EN ISO 4373:2008ISO 4373:2008(E) 2 ISO 2008 All rights reservedThe manufacturer has to state

30、 the physical principle of the measuring device in order to allow the user to judge the devices suitability for the proposed environment. Table 1 Performance classes of water level measuring devices Class Resolution Range Nominal uncertainty Performance class 1 1 mm 2 mm 10 mm 1,0 m 5,0 m 20 m u 0,1

31、 % of range Performance class 2 2 mm 5 mm 20 mm 1,0 m 5,0 m 20 m u 0,3 % of range Performance class 3 10 mm 50 mm 200 mm 1,0 m 5,0 m 20 m u 1 % of range 4.3 Maximum rate of change As water levels may rise and fall rapidly in some applications, in order to provide guidance on suitability, the manufac

32、turer shall state on the equipment specification sheet and in the instruction manual: a) the maximum rate of change which the instrument can follow without damage; b) the maximum rate of change which the instrument can tolerate without suffering a change in calibration; c) the response time of the i

33、nstrument. 4.4 Environment 4.4.1 General Water level measuring devices shall operate within the ranges of temperature in 4.4.2 and the ranges of relative humidity in 4.4.3. 4.4.2 Temperature Water level measuring devices shall operate within the following temperature classes: Temperature class 1: 30

34、 C to +55 C; Temperature class 2: 10 C to +50 C; Temperature class 3: 0 C to +50 C. 4.4.3 Relative humidity Water level measuring devices shall operate within the following relative humidity classes: Relative humidity class 1: 5 % to 95 % including condensation; Relative humidity class 2: 10 % to 90

35、 % including condensation; Relative humidity class 3: 20 % to 80 % excluding condensation. BS EN ISO 4373:2008ISO 4373:2008(E) ISO 2008 All rights reserved 34.5 Timing 4.5.1 General Where timing, either analogue or digital, is part of the instrument specification, the timing method used shall be cle

36、arly stated on the instrument and in the instruction manual. NOTE It is recognized that digital timing is inherently more accurate than analogue timing. 4.5.2 Digital The uncertainty of digital timing devices used in water level measuring devices shall be within 150 s at the end of a period of 30 da

37、ys, within the range of environmental conditions defined in 4.4. 4.5.3 Analogue The uncertainty of analogue timing devices used in water level measuring devices shall be within 15 min at the end of a period of 30 days, within the range of environmental conditions defined in 4.4. 5 Recording 5.1 Char

38、t recorders Where a chart recorder is to be used as the primary source of data, the resolution and uncertainty parameters shall take account of changes in the dimensions of the recording medium due to atmospheric variables. NOTE Chart recorders have been superseded to a large extent by data logging

39、devices. However, they are still used as back-up units or to provide rapid visual assessment of flow changes on site. 5.2 Data loggers A data logger shall be able to store at least the equivalent of four digits per reading. Where a data logger includes the interface electronics, the resolution and u

40、ncertainty shall relate to the stored value. 6 Enclosure The performance of the enclosure shall be stated in terms of the IP classification system in accordance with IEC 60529. It shall be stated whether or not any parts in contact with water are suitable for contact with potable water. It shall be

41、stated whether or not the equipment may be used in a potentially explosive environment in accordance with IEC 60079-10. 7 Installation The manufacturer shall provide clear instructions for the installation of water level measuring devices. BS EN ISO 4373:2008ISO 4373:2008(E) 4 ISO 2008 All rights re

42、served8 Estimation of measurement uncertainty 8.1 General The uncertainty of a value derived from primary measurements may be due to a) unsteadiness of the value being measured (waves on the water surface), or b) resolution of the measurement process (the eyes resolution of submillimetre distance).

43、Two methods of estimation, Type A and Type B, are described in the Guide to the expression of uncertainty in measurement for relating the dispersion of values to the probability of “closeness” to mean value. 8.2 Type-A estimation A Type-A estimation is determined directly from the standard deviation

44、 of a large number of measurements. (Note that the distribution of these results need not be Gaussian.) Type-A estimations can be readily computed from continuous measurements when the dispersion is not masked by hysteresis of the measurement process. Of course, the dispersion must exceed by a signi

45、ficant margin the resolution of the measurement process. 8.3 Type-B estimation A Type-B estimation is assigned to a measurement process for which large numbers of measurements are not available or to a measurement with defined limits of resolution. To define a Type-B uncertainty, the upper and lower

46、 limits of the dispersion or the upper and lower limits of resolution are used to define the limits of a probability diagram whose shape is selected to represent the dispersion, i.e. uniform dispersions would have a rectangular distribution; dispersions with most measurements congregated about the m

47、ean value would have a triangular distribution. Allocation of probability distributions is described in Annex A. The relationship between the uncertainty of primary measurements and the value of the uncertainty of the result is derived from the formula defining the relationship between the value and

48、 its primary measurements. Sensitivities are the partial derivatives of the value with respect to each primary measurement. In the case of level, its relationship to primary measurement is generally linear. Sensitivity coefficients would then be equal to 1. 8.4 Level measurement datum Level measurem

49、ent is not absolute measurement; it is always relative to a datum, for example a local benchmark or the elevation of a weir crest. The uncertainty associated with the datum should be combined with the uncertainty of the derived value. 8.5 Combining primary measurement uncertainties To determine the uncertainty of the derived value, U, it is necessary to combine the uncertainties of all primary measurements, u, thus, ()( )( )22level level datum level measurementUu u=+ This illustrates the method when combining the uncertainty of a re