BS-EN-ISO-6416-2005.pdf

BRITISH STANDARD BS EN ISO 6416:2005 Hydrometry Measurement of discharge by the ultrasonic (acoustic) method The European Standard EN ISO 6416:2005 has the status of a British Standard ICS 17.120.20 ? Licensed Copy: sheffieldun sheffieldun, na, Sat Nov 18 04:19:35 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS EN ISO 6416:2005 This British Standard was published under the authority of the Standards Policy and Strategy Committee on 21 October 2005 © BSI 21 October 2005 ISBN 0 580 46676 0 National foreword This British Standard is the official English language version of EN ISO 6416:2005. It is identical with ISO 6416:2004. It supersedes BS 3680-3E:1993 which is withdrawn. The UK participation in its preparation was entrusted by Technical Committee CPI/113, Hydrometry, to Subcommittee CPI/113/1, Velocity area methods, which has the responsibility to: A list of organizations represented on this subcommittee can be obtained on request to its secretary. Cross-references The British Standards which implement international or European publications referred to in this document may be found in the BSI Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “Search” facility of the BSI Electronic Catalogue or of British Standards Online. This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. aid enquirers to understand the text; present to the responsible international/European committee any enquiries on the interpretation, or proposals for change, and keep UK interests informed; monitor related international and European developments and promulgate them in the UK. Summary of pages This document comprises a front cover, an inside front cover, the EN title page, the EN foreword page, the ISO title page, pages ii to v, a blank page, pages 1 to 50, an inside back cover and a back cover. The BSI copyright notice displayed in this document indicates when the document was last issued. Amendments issued since publication Amd. No. DateComments Licensed Copy: sheffieldun sheffieldun, na, Sat Nov 18 04:19:35 GMT+00:00 2006, Uncontrolled Copy, (c) BSI EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM EN ISO 6416 August 2005 ICS 17.120.20 English Version Hydrometry - Measurement of discharge by the ultrasonic (acoustic) method (ISO 6416:2004) Hydrométrie - Mesure du débit à l'aide de la méthode ultrasonique (acoustique) (ISO 6416:2004) Hydrometrie - Messung des Abflusses mit dem Ultraschallverfahren (akustisches Verfahren) (ISO 6416:2004) This European Standard was approved by CEN on 11 July 2005. CEN members are bound to comply 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 Secretariat 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 official versions. CEN members are the national standards bodies of Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMITÉ EUROPÉEN DE NORMALISATION EUROPÄISCHES KOMITEE FÜR NORMUNG Management Centre: rue de Stassart, 36 B-1050 Brussels © 2005 CENAll rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN ISO 6416:2005: E Licensed Copy: sheffieldun sheffieldun, na, Sat Nov 18 04:19:35 GMT+00:00 2006, Uncontrolled Copy, (c) BSI Foreword The text of ISO 6416:2004 has been prepared by Technical Committee ISO/TC 113 “Hydrometric determinations“ of the International Organization for Standardization (ISO) and has been taken over as EN ISO 6416:2005 by 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 February 2006, and conflicting national standards shall be withdrawn at the latest by February 2006. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. Endorsement notice The text of ISO 6416:2004 has been approved by CEN as EN ISO 6416:2005 without any modifications. EN EN ISO 6416:2005 Licensed Copy: sheffieldun sheffieldun, na, Sat Nov 18 04:19:35 GMT+00:00 2006, Uncontrolled Copy, (c) BSI Reference number ISO 6416:2004(E) INTERNATIONAL STANDARD ISO 6416 Third edition 2004-07-01 Hydrometry Measurement of discharge by the ultrasonic (acoustic) method Hydrométrie Mesure du débit à l'aide de la méthode ultrasonique (acoustique) EN ISO 6416:2005 Licensed Copy: sheffieldun sheffieldun, na, Sat Nov 18 04:19:35 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ii Licensed Copy: sheffieldun sheffieldun, na, Sat Nov 18 04:19:35 GMT+00:00 2006, Uncontrolled Copy, (c) BSI iii Contents Page Foreword.v 1 Scope1 2 Normative references .1 3 Terms and definitions.1 4 Applications.1 4.1 Open channels 1 4.2 Multiple channels2 4.3 Closed conduits 2 5 Method of measurement.3 5.1 Discharge.3 5.2 Calculation of discharge from the transit-time measurement3 6 Flow velocity determination by the ultrasonic (transit time) method3 6.1 Principle.3 6.2 Sound propagation in water.6 7 Gauge configuration.10 7.1 General.10 7.2 Single-path systems .11 7.3 Multi-path systems12 7.4 Crossed path systems12 7.5 Reflected-path systems14 7.6 Systems using transponders.15 7.7 Systems using divided cross-sections.16 7.8 Sloping paths 17 8 Calculation of discharge 17 8.1 Single-path systems .17 8.2 Multi-path systems17 8.3 Systems with transducers in the channel21 9 System calibration 21 9.1 General.21 9.2 Single-path systems .22 10 Site selection.24 10.1 Practical constraints.24 10.2 Physical constraints of the measurement site.25 10.3 Physical constraints which are distant from the measurement site .25 11 Site survey Before design and construction.26 11.1 General.26 11.2 Visual survey.26 11.3 Survey of the cross-section.27 11.4 Survey of velocity distribution 27 11.5 Survey of signal propagation.28 11.6 Other survey activities28 12 Operational measurement requirements28 12.1 General.28 12.2 Basic components of flow determination.29 12.3 Water velocity determination.29 12.4 Determination of water stage or depth.29 EN ISO 6416:2005 Licensed Copy: sheffieldun sheffieldun, na, Sat Nov 18 04:19:35 GMT+00:00 2006, Uncontrolled Copy, (c) BSI iv 12.5 Channel width30 13 Gauging station equipment30 13.1 General .30 13.2 Design and construction of equipment.31 13.3 Reflectors.32 13.4 Civil engineering works35 13.5 Signal timing and processing35 13.6 System self-checking37 13.7 Site-specific data (or site parameters)38 13.8 Clock and calendar38 13.9 System performance criteria38 13.10 System output40 13.11 Installation40 13.12 Commissioning41 13.13 Operating manual41 13.14 Maintenance.41 14 Measurement uncertainties43 14.1 General .43 14.2 Definition of uncertainty.43 14.3 Uncertainty in discharge 44 Bibliography50 EN ISO 6416:2005 Licensed Copy: sheffieldun sheffieldun, na, Sat Nov 18 04:19:35 GMT+00:00 2006, Uncontrolled Copy, (c) BSI v Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International 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 with 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 technical 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 to 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 6416 was prepared by Technical Committee ISO/TC 113, Hydrometry, Subcommittee SC 1, Velocity area methods. This third edition cancels and replaces the second edition (ISO 6416:1992), which has been technically revised. EN ISO 6416:2005 Licensed Copy: sheffieldun sheffieldun, na, Sat Nov 18 04:19:35 GMT+00:00 2006, Uncontrolled Copy, (c) BSI blank EN ISO 6416:2005 Licensed Copy: sheffieldun sheffieldun, na, Sat Nov 18 04:19:35 GMT+00:00 2006, Uncontrolled Copy, (c) BSI 1 Hydrometry Measurement of discharge by the ultrasonic (acoustic) method 1 Scope This International Standard describes the establishment and operation of an ultrasonic (transit-time) gauging station for the continuous measurement of discharge in a river, an open channel or a closed conduit. It also describes the basic principles on which the method is based, the operation and performance of associated instrumentation and procedures for commissioning. It is limited to the “transit time of ultrasonic pulses” technique, and is not applicable to systems that make use of the “Doppler shift” or “correlation” or “level-to-flow” techniques. This International Standard is not applicable to measurement in rivers with ice. 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 (including any amendments) applies. ISO 772:1996, Hydrometric determinations Vocabulary and symbols ISO 4373:1995, Measurement of liquid flow in open channels Water-level measuring devices 3 Terms and definitions For the purposes of this document, the terms and definitions given in ISO 772 apply. 4 Applications 4.1 Open channels 4.1.1 The method is suitable for use in river flow measurement, a significant advantage being additional freedom from siting constraints in comparison with other available techniques. In particular, the method does not demand the presence of a natural control or the creation of a man-made control at the proposed gauge location, as it does not rely upon the establishment of a unique relation between water level and discharge. 4.1.2 Gauges using the method are capable of providing highly accurate flow determinations over a range of flows contained within a defined gauge cross-section. They are tolerant of the backwater effects created by tides, downstream tributary discharges, downstream weed growth, reservoir or head-pond water level manipulation, and periodic channel obstruction. NOTE For locations subjected to significant bed level or profile instability, it may not be possible to use gauges. EN ISO 6416:2005 Licensed Copy: sheffieldun sheffieldun, na, Sat Nov 18 04:19:35 GMT+00:00 2006, Uncontrolled Copy, (c) BSI 2 4.1.3 Use of the method usually creates no obstruction to navigation. It creates no significant hazard or loss of amenity for other channel users or riparian interests. However, some species of fish may be sensitive to some types of ultrasonic signal. The gauge can be designed to be physically unobtrusive. 4.1.4 For use in remote locations, the electronic equipment can be designed to operate from battery power. To economise on power consumption, the system is usually set to sample the flow for short periods and to return to a quiescent condition between samples. (see 10.1.3 and 13.9.5). 4.1.5 The method is not really suitable for use when the channel is covered with ice, because of the difficulty of determining the cross-sectional area of the water. Although this is a limitation of use, the method may still have value in determining water velocity under the ice, if transducers can be positioned in unfrozen water. 4.2 Multiple channels 4.2.1 At locations where the total flow is divided between two or more physically separate channels, such as under a multiple-arched bridge, the instrumentation can be configured to determine individual channel flows separately and then to combine these to create a single unified determination of flow. 4.2.2 If flow may not readily be contained within a single well-defined cross-section, and in particular if there is significant flow that bypasses the main gauge cross-section by way of an extensive flood plain, it may be possible to subdivide the flood plain into a series of “channels” in which the flow can be measured. 4.2.3 A station designer may decide to provide a comprehensive flood-plain measurement capability by this means or may, alternatively, simply provide a flow or velocity sampling facility. In the latter situation, gauged cross-sections may be constructed in the flood plain. These do not normally provide total coverage, but merely provide locations at which flood-plain flow can be sampled for subsequent examination and analysis. 4.2.4 It should be noted that systems designed to determine flood-plain flow may suffer from the practical difficulties of a) inability to commission the system due to there being no water in the measurement section, b) maintenance of the section, including weed cutting, debris clearance and repair of vandalism. 4.3 Closed conduits The ultrasonic method can also be applied to the measurement of flow in closed conduits, including both storm-water and foul sewers, under both free-flowing and surcharged conditions. For systems used in foul sewers, special attention should be paid to the following: a) the source of the water, especially whether it is from an aeration tank or from a section of channel containing aerators or from a hydro-electr