Electromagnetic Flow Meter Guide
About Electromagnetic Flow Meters
Magnetic flow meters provide obstruction free flow measurement and so are suitable for all conductive liquids including: chemicals, food stuffs, pulps, acids, pharmaceuticals, slurries and effluent. Their high accuracy is unaffected by changes in fluid viscosity, line pressure, temperature or density.
How do Mag flow meters work ?
The operating principle of the electromagnetic flow meter is based on Faraday's law of magnetic induction: The voltage induced across any conductor, as it moves at right angles through a magnetic field, is proportional to the velocity of that conductor. The voltage induced within the fluid is measured by two diametrically opposed internally mounted electrodes. The induced signal voltage is proportional to the product of the magnetic flux density, the distance between the electrodes and the average flow velocity of the fluid.
Figure 1: Electromagnetic Flow Meter Operational Principle (in-line type)
Advantages:
♦ No moving parts or obstructions to the flow path
♦ Littlle or zero pressure drop across the body
♦ High Flow turndown 300:1 or better
♦ Multi-directional
♦ Hygienic Design options
♦ Suitable for hazardous areas
♦ Low cost of ownership / minimal service costs / Longevity of service
♦ High dynamic response to rapid changes in flow
♦ Potable water approved liners available WRAS, ACS etc
♦ Meter verification is possible rather than calibration by removal
♦ Suitable for slurries - model dependant
♦ Relatively unaffected by viscosity, temperature and pressure as long as the mag flow meter is selected based on the correct process conditions
Disadvantages:
♦ Only effective on conductive fluids
♦ Electrodes can in some instances become coated, reducing effectiveness / operation
♦ Strong Local magnetic fields can affect the measurement given
♦ Larger models can be extremely heavy
♦ No suitable for liquids laden with entrained gas
♦ Proper grounding is required, especially in plastic pipe systems
♦ Consideration should be given to flow profile vs installation location
Typical applications:
⊃ Water & Wastewater
⊃ Chemical
⊃ Mining/Aggregates
⊃ Pulp & Paper
⊃ Power & Utilities
⊃ District Heating/Cooling
We provide a wide range of magnetic flow meters including; battery powered, models with flanged and hygienic connections and ATEX approved mag flowmeters, all with a choice of liner materials, outputs, connections and options for data logging, telemetry and displays.
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