Book contents
- Front Matter
- Contents
- Preface
- Acknowledgments
- Nomenclature
- Chapter 1 Introduction
- Chapter 2 Fluid Mechanics Essentials
- Chapter 3 Specification, Selection, and Audit
- Chapter 4 Calibration
- Chapter 5 Orifice Plate Meters
- Chapter 6 Venturi Meter and Standard Nozzles
- Chapter 7 Critical Flow Venturi Nozzle
- Chapter 8 Other Momentum-Sensing Meters
- Chapter 9 Positive Displacement Flowmeters
- Chapter 10 Turbine and Related Flowmeters
- Chapter 11 Vortex-Shedding, Swirl, and Fluidic Flowmeters
- Chapter 12 Electromagnetic Flowmeters
- Chapter 13 Ultrasonic Flowmeters
- Chapter 14 Mass Flow Measurement Using Multiple Sensors for Single- and Multiphase Flows
- Chapter 15 Thermal Flowmeters
- Chapter 16 Angular Momentum Devices
- Chapter 17 Coriolis Flowmeters
- Chapter 18 Probes for Local Velocity Measurement in Liquids and Gases
- Chapter 19 Modern Control Systems
- Chapter 20 Some Reflections on Flowmeter Manufacture, Production, and Markets
- Chapter 21 Future Developments
- Bibliography
- A Selection of International Standards
- Conferences
- References
- Index
Chapter 12 - Electromagnetic Flowmeters
Published online by Cambridge University Press: 22 September 2009
- Front Matter
- Contents
- Preface
- Acknowledgments
- Nomenclature
- Chapter 1 Introduction
- Chapter 2 Fluid Mechanics Essentials
- Chapter 3 Specification, Selection, and Audit
- Chapter 4 Calibration
- Chapter 5 Orifice Plate Meters
- Chapter 6 Venturi Meter and Standard Nozzles
- Chapter 7 Critical Flow Venturi Nozzle
- Chapter 8 Other Momentum-Sensing Meters
- Chapter 9 Positive Displacement Flowmeters
- Chapter 10 Turbine and Related Flowmeters
- Chapter 11 Vortex-Shedding, Swirl, and Fluidic Flowmeters
- Chapter 12 Electromagnetic Flowmeters
- Chapter 13 Ultrasonic Flowmeters
- Chapter 14 Mass Flow Measurement Using Multiple Sensors for Single- and Multiphase Flows
- Chapter 15 Thermal Flowmeters
- Chapter 16 Angular Momentum Devices
- Chapter 17 Coriolis Flowmeters
- Chapter 18 Probes for Local Velocity Measurement in Liquids and Gases
- Chapter 19 Modern Control Systems
- Chapter 20 Some Reflections on Flowmeter Manufacture, Production, and Markets
- Chapter 21 Future Developments
- Bibliography
- A Selection of International Standards
- Conferences
- References
- Index
Summary
INTRODUCTION
The possibility of inducing voltages in liquids moving through magnetic fields was known by Faraday in 1832, but the first flowmeter-like device was reported by Williams in 1930. The first real advance in the subject came from the medical field where Kolin (1936, 1941) introduced many ideas that are now standard practice.
The industrial interest in electromagnetic flowmeters (sometimes referred to as EM or magnetic flowmeters) grew in the 1950s with
the Tobiflux meter (Tobi 1953) in Holland for rayon viscose, sand and water, and acid slurries;
Foxboro, to whom the patent was assigned in 1952;
the first commercial instruments in 1954 (Balls and Brown 1959).
nuclear reactor applications;
the work that resulted in an essential book by J. A. Shercliff (1962).
In this chapter, we shall concentrate on the application of the flowmeter to fluids that are of low conductivity, such as water-based liquids (Baker 1982). The flowmeter has also been used with liquid metals (Baker 1969, 1970b, 1977), and a few designs have been built for use with nonconducting dielectric liquids (Al-Rabeh et al. 1978). The reader is referred to the original papers because space prevents their inclusion here. Three papers by Wyatt (1961, 1977, 1982), a pioneer in blood flow measurement research, are referenced for those interested.
OPERATING PRINCIPLE
We start with the simple induction, which occurs when a conductor moves through a magnetic field. Figure 12.1 shows a copper wire cutting the flux of a permanent magnet.
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- Flow Measurement HandbookIndustrial Designs, Operating Principles, Performance, and Applications, pp. 282 - 311Publisher: Cambridge University PressPrint publication year: 2000
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