BS ISO 9213:2004:2005 Edition
$142.49
Measurement of total discharge in open channels. Electromagnetic method using a full-channel-width coil
| Published By | Publication Date | Number of Pages |
| BSI | 2005 | 26 |
This International Standard specifies procedures for the establishment and operation of a gauging station, equipped with an electromagnetic flow meter, in an open channel or a closed conduit with a free water surface.
This International Standard is applicable to configurations where an artificial magnetic field is generated through which the entire body of water flows. The induced voltage is sensed in such a way that all elements of the moving water contribute. The equipment described normally requires an electrical mains power supply.
This International Standard is not applicable to devices sampling only part of the flowing body of water (e.g. velocity meters) or to flow meters which operate by using the Earth’s magnetic field.
PDF Catalog
| PDF Pages | PDF Title |
|---|---|
| 3 | TitlePage – Measurement of total discharge in open channels�— Electromagnetic method using a full… |
| 5 | TableofContent – Contents Page |
| 6 | Foreword – Foreword |
| 7 | Scope – 1��� Scope NormativeReference – 2��� Normative references Clause1 – 4��� Principles of operation and practice UntitledSubclause2 – 4.1��� This is a velocity-area method of discharge determination. The electr… |
| 8 | UntitledSubclause2 – 4.2��� The principle is widely applied to flow meters in circular pipes runn… UntitledSubclause2 – 4.3��� Bevir’s formula for the potential generated between electrodes placed… |
| 9 | UntitledSubclause2 – 4.4��� In this simple case, if the water depth is UntitledSubclause2 – 4.5��� However, there is a sensitivity to non-uniform velocity distribution … UntitledSubclause2 – 4.6��� With most channels, the material comprising the bed and sides will ha… |
| 10 | UntitledSubclause2 – 4.7��� A layer of silt settling on the bed (or the protective layer describe… UntitledSubclause2 – 4.8��� The value of induced voltage in a practical application is generally … UntitledSubclause2 – 4.9��� Since the coil current is alternating, the possibility exists of elec… |
| 11 | UntitledSubclause2 – 4.10��� From Clause1 – 5��� Applications UntitledSubclause2 – 5.1��� The electromagnetic gauge is particularly suited to the measurement o… UntitledSubclause2 – 5.2��� Different versions of the electromagnetic gauge are suitable for meas… UntitledSubclause2 – 5.3��� The advantages of the method include the following: |
| 12 | UntitledSubclause2 – 5.4��� There are however some disadvantages associated with the method, such as Clause1 – 6��� Selection of site UntitledSubclause2 – 6.1��� A site survey should be carried out if necessary as outlined in UntitledSubclause2 – 6.2��� Owing to the high power consumption of the coil, equipment intended t… UntitledSubclause2 – 6.3��� The site shall afford adequate on-bank working space for handling the… UntitledSubclause2 – 6.4��� The site characteristics shall be such that the calibration of the st… UntitledSubclause2 – 6.5��� Sites shall be selected where there is no spatial variation in water … Clause1 – 7��� Design and construction Subclause2 – 7.1��� General |
| 14 | Subclause2 – 7.2��� System equipment Subclause3 – 7.2.1��� Coil UntitledSubclause4 – 7.2.1.1��� The sensitivity of the equipment to the flow is improved by incre… |
| 15 | UntitledSubclause4 – 7.2.1.2��� Any electrical leakage between the coil and the water in the chan… UntitledSubclause4 – 7.2.1.3��� The coil shall be installed in ducting (normally of about UntitledSubclause4 – 7.2.1.4��� For convenience, the coil may be wound with a multi-core cable an… UntitledSubclause4 – 7.2.1.5��� In cases where installation is in potentially explosive atmospher… UntitledSubclause4 – 7.2.1.6��� The frequency at which the magnetic field is reversed shall be lo… UntitledSubclause4 – 7.2.1.7��� A typical coil design is described in Subclause3 – 7.2.2��� Electrodes UntitledSubclause4 – 7.2.2.1��� It is recommended that the electrodes be made from stainless stee… UntitledSubclause4 – 7.2.2.2��� In channels containing foul water which is liable to putrify, the… UntitledSubclause4 – 7.2.2.3��� In the event of a lightning strike in the vicinity of the gauge, … UntitledSubclause4 – 7.2.2.4��� The inductive or capacitive coupling between the signal cable and… UntitledSubclause4 – 7.2.2.5��� In open channels, the electrodes may be supported in guides mount… |
| 16 | Subclause3 – 7.2.3��� Insulating membrane UntitledSubclause4 – 7.2.3.1��� An insulating membrane shall be used which is strong enough to wi… UntitledSubclause4 – 7.2.3.2��� The membrane shall be mechanically anchored and sealed at the lea… UntitledSubclause4 – 7.2.3.3��� In practice, the membrane may be covered by a variety of material… |
| 17 | UntitledSubclause4 – 7.2.3.4��� The membrane shall not be punctured, except along the edges for a… UntitledSubclause4 – 7.2.3.5��� In a concrete channel the upstream leading edge and sides of the … UntitledSubclause4 – 7.2.3.6��� It is recommended that the length of the lining be no less than 1… UntitledSubclause4 – 7.2.3.7��� In closed conduits a special preformed section may be inserted in… Subclause3 – 7.2.4��� Instrumentation unit UntitledSubclause4 – 7.2.4.1��� The instrumentation shall consist of: UntitledSubclause4 – 7.2.4.2��� To obtain meaningful determinations of flow, measurements shall b… Subclause3 – 7.2.5��� Water level measurement Subclause2 – 7.3��� Measurement of coil current and electrode voltage |
| 18 | Subclause2 – 7.4��� Signal processing UntitledSubclause3 – 7.4.1��� The equipment shall measure the difference in electrical potential … UntitledSubclause3 – 7.4.2��� The electrical interference is regarded as random and so will in th… UntitledSubclause3 – 7.4.3��� When making comparison for calibration purposes, the averaging peri… Subclause2 – 7.5��� Power supply failure Clause1 – 8��� Uncertainties in flow measurement Subclause2 – 8.1��� Calibration graph Subclause2 – 8.2��� Single determination of discharge UntitledSubclause3 – 8.2.1��� The uncertainty in a single determination of discharge may be calcu… |
| 19 | UntitledSubclause3 – 8.2.2��� The component uncertainties are the following: Clause1 – 9��� Gauge calibration and verification UntitledSubclause2 – 9.1��� Provided always that the design of an electromagnetic gauge is such t… UntitledSubclause2 – 9.2��� The measurand/determinand relationship may take more than one form, d… UntitledSubclause2 – 9.3��� Once the general form of a relation is established, the optimum value… UntitledSubclause2 – 9.4��� A series of calibration determinations should be such as to have suff… UntitledSubclause2 – 9.5��� The independent determinations of flow should be made with very great… UntitledSubclause2 – 9.6��� Care shall be taken to ensure that the act of check gauging does not … UntitledSubclause2 – 9.7��� Annex�D UntitledSubclause2 – 9.8��� Once a sufficiently numerous and range-representative calibration sam… UntitledSubclause2 – 9.9��� Following the satisfactory completion of gauge calibration, it would … |
| 20 | AnnexInformative – Site survey for electrical interference |
| 21 | AnnexInformative – Design aspects of the electromagnetic coil |
| 22 | AnnexInformative – Numerical example of the calculation of uncertainty |
| 23 | AnnexNormative – Gauge calibration procedure UntitledClause1 – D.1��� A series of calibration check gaugings should be carried out to establis… UntitledClause1 – D.2��� All current meter gauging for calibration purposes should be undertaken … UntitledClause1 – D.3��� Multi-point gauging should be adopted as the norm for calibration gaugin… UntitledClause1 – D.4��� In the course of a calibration gauging steps should be taken at the outs… |
| 24 | UntitledClause1 – D.5��� The procedure for undertaking both formal calibration and verification g… UntitledClause1 – D.6��� As a matter of policy, calibration gauging at any given site should not … UntitledClause1 – D.7��� Individual gaugings should be most carefully vetted before being accepte… UntitledClause1 – D.8��� The minimum target calibration gauging data set should have the followin… UntitledClause1 – D.9��� Once a set of calibration data has been obtained, the data should be sub… |
| 25 | Bibliography – Bibliography |
