BS EN ISO Measurement of conductive liquid flow in closed conduits – Method using electromagnetic flowmeters. BS EN ISO Measurement of conductive liquid flow in closed conduits. Method using electromagnetic flowmeters. standard by British. Home; ISO File Size: 1 file, MB; Same As: BS EN ISO , BS EN ISO Document History. ISO
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General introduction and classification. Inside diameters, cross-sections, tolerances and designation codes.
BS EN ISO – PDF Free Download
Ensure use of the most current version of this document by searching British Standards Online at bsonline. It is identical with ISO It supersedes BS This standard now forms Part 1 of two Parts of BS on electromagnetic flowmeters as follows: Installation dimensions of flanged type electromagnetic flowmeters.
Measurement of fluid flow in closed conduits Section 2. Users of British Standards are responsible for their correct application. Summary of pages This document comprises a front cover, an inside front cover, pages i to iv, the EN ISO title page, pages 2 to 20, an inside 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 the inside front cover. 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 Up-to-date lists and bibliographical references concerning such bx standards may be obtained on application lso the Central Secretariat or to any CEN member.
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. 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publication of an identical text or by endorsement, at the latest by Marchand conflicting national standards shall be withdrawn at the latest by March It covers their installation, operation, performance and calibration.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 magnetically permeable slurries, liquid metals nor usage in medical applications. This International Standard covers flowmeter types in both a.
Ido of these are extracted from ISO for ease of reference. 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 below. The electromagnetic flowmeter consists of a primary device and one or more secondary devices. This equipment may be mounted on the primary device 3.
This usage also aligns with that in ISO If the field isl 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.
BS EN ISO 6817
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 iwo. Meters based on this principle are Equation 4 may be interpreted in various ways to capable of measuring flow in either direction through the meter tube. The system produces an output signal proportional to volume flow-rate or average velocity. Its application is generally limited only by isl requirement that the metered liquid shall be electrically conductive and non-magnetic.
The primary and the secondary devices can be combined in a single assembly. Other specific designs are also available, for example, a cast steel case with the coils insulated inside the case and liners fitted internally to this again. Flanges are usually provided to connect the primary device to the plant pipework, although flangeless meters are available in isi sizes. The coils producing the magnetic field may be energized from the normal single-phase supply, or from some other supply.
The coil assembly is either mounted isp or encapsulated within the pipe. In the latter case, the pipe may be made of magnetic material.
BS EN ISO 6817:1997
The pulsed direct current d. The meter samples the signal at zero magnetic field and zero adjusts, but does not differentiate against all other spurious signals. General guidance on various aspects of the primary device is set out in 7. The same applies b the offset is in the negative direction. General guidance on the function and installation of secondary devices is presented in 7. Minimum operational conductivity requirements should be obtained from the manufacturers.
The internal impedance of the primary device obviously depends upon the liquid conductivity, and very large changes in this impedance may produce errors in the output signal. If the conductivity is not uniform throughout the meter, errors may also occur. A heterogeneous fluid composed of small particles uniformly distributed in a medium can be considered as vs homogeneous liquid.
Deposition of electrically conducting layers on the inside surface of the liner may also lead to errors. Flow pattern effects are described in 7.
If, in this case, the mean axial velocity corresponding to the maximum flow-rate is less than that recommended by the manufacturer, 8617 primary device with a smaller hs should be used. A primary device with a bore smaller than that of the adjacent pipework may also be used for other reasons, e. Information on the bz tolerances for matching the pipe and meter tube bores is given in ISO Figure 4 — Principle of pulsed d.
Locations close to electrical equipment which may interfere with the flow measurement signal, or locations where currents may be induced in the primary device, should be avoided. If necessary, warning devices should be installed to preserve measurement integrity. Partially-filled primary device meters bd used, for example in sewage applications, but these merit special consideration outside the scope of this International Standard.
Though this can be 7. In this case, the inlet and outlet straight pipe sections shall be the same size as the flowmeter see 7. Eccentric taper pipes shall be used when the pipeline is horizontal, to prevent air pockets from forming. When designing the piping ej, access for installing and removing the primary device as rn as access to the electrical connections should be provided. Means should be provided for adjusting and aligning the adjacent pipework.
Extra care should be taken during pipework construction to prevent excessive strain on the primary device, both during and after installation. Every effort should be made to minimize piping loads and resulting strains at the primary device connecting flanges, particularly in plastic meters which are not intended to sustain piping bx.
Permissible values should be checked with the manufacturer. It is essential that the primary device is correctly aligned on the pipe axis when it is bolted into the pipework. Wafer types require special care. Flange bolts should be tightened evenly and in moderation in order to avoid damage to the lining.
The manufacturer should state the maximum permissible torque. Care vs be taken when handling the primary device; slings around the primary device, or lifting lugs, should be used. Lifting by any means that could damage the liner, for example, hooks in the bore, shall not be used.
In the case where cathodic protection is used to protect buried pipework, this precaution becomes essential see 7. The connection between the liquid and the primary device body may be made by contact with the adjacent pipework; bz, where insulated or non-conductive pipework is used, by conductive earthing rings or electrodes. Equipotential conductive links usually copper braids should be fitted across both flange joints bx Figure 6. The power supply should be taken from a point that is as free as possible from transient voltages.
Instructions in relation to electrical grounding of the flowmeter hs shall be rigidly observed. The scraper is driven by an external electric motor via fluid pressure seals. It may be used continuously or intermittently. This method is becoming less commonly used in modern electromagnetic flowmeters. The shaft length and the frequency of ultrasound are chosen to produce an antinode at the electrode face. Deposits are removed by the resultant local cavitation at the electrode.
This approach is generally used on crystalline-type coatings. The resultant rapid gas evolution causes removal of deposits. This approach is generally used on oily, greasy and sludge-type coatings. Heating of the electrodes e also be used to remove fat or grease deposits from sewage.
In particular, direct solar irradiation shall be avoided. These cables should be as short bx possible and not exceed the limit imposed by the manufacturer.
Care should be taken to ensure that signal cables are not routed in proximity to high current cables. NOTE 2 Additional information such as trademark, mass of unit, date of manufacture, flow direction arrow, etc. Reference should also be made to ISO for fuller information on this subject. It is current practice to specify a reference accuracy envelope over a designated flowrate range.
Typical reference accuracy envelopes are shown in Figure 7.
A summary of uncertainty analysis in this context is given in clause While these effects are normally compensated for in the secondary device, limits of error for each influencing quantity should be specified by the manufacturer. However, it is useful to recall some general principles and to present the way in which they isp to measurement using an electromagnetic flowmeter. The fitting of curves to specific sets of calibration or user data from flow measurement devices is covered in Bbs and ISO Systematic errors cannot be reduced by repeating measurements, since they arise from the characteristics of the measuring apparatus, the installation and the flow characteristics.
This oso comprises both systematic and random components depending upon the conditions of the flowmeter calibration, and can vary for each test point of the calibration curve. Although systematic errors have been distinguished from random errors, the probability distribution of the possible values of each systematic component is essentially Gaussian.
The combination of the random and systematic errors may therefore be treated as though all were truly random and, according to the Fnthe relative standard deviation of the flow-rate measurement may be taken as the square root of the sum of the squares of the relative standard deviations arising from isoo various sources. It is essential that account is taken of any other chemicals liable to pass through the meter tube, such as sterilizing agents, cleaners and solvents.