Magnetic Flow Meter Expertise
To ensure that your magnetic flow meter, also known as an electromagnetic flow meter, keeps functioning within optimal parameters we’ve gathered some best practice tips based on our years of experience as well as input from our customers.
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- Select magnetic flow sensor materials that are chemically compatible with all expected process fluids and cleaning/flushing agents. Beware of steam out conditions that require a meter rated for higher temperatures and full vacuum.
- Orient the mag meter properly to keep the meter full and avoid two-phase conditions. Flow upward through the flow meter if possible.
- Use the recommended upstream and downstream pipe lengths to ensure proper fluid conditioning for best flow measurement results. Consult the manufacturer if space requirements won’t allow the minimum diameters.
- If insulation is used, do not cover the coil housing or electronics as these components can overheat and fail.
- Size the magnetic flow meter properly to achieve best flow measurement performance across the full process flow range. Most magnetic flow meters will perform fine when selected to match the process pipe size, but for processes that operate at low flowing velocities, adding a reducer to accommodate a smaller magnetic sensor will improve the measurement accuracy (by increasing the fluid velocity through the sensor).
- Isolate the wiring from the transmitter to the magnetic sensors in its own conduit. Do not run Mag wiring in a conduit shared with any other equipment wiring. Any electrical interference can cause measurement offsets.
- Avoid stripping too much insulation from magnetic meter wiring. Any exposed wires that are not covered by a braided shield can allow extraneous electronic interference into the measurement circuits.
- Ensure the magnetic flow meter electronics are grounded to the process fluid (in addition to earth ground) by using ground straps, grounds rings, lining protectors, or a dedicated grounding electrode.
- Verify the calibration constants from the flow sensor are reflected properly in the electronics. For sensors capable of driving the Magnetic coils at multiple frequencies, there should be a unique calibration number for each coil drive frequency.
- Perform a zero calibration if using an AC-powered meter, or when operating at high coil drive frequencies on pulsed-DC meters.
- Determine a field baseline for the circuit health monitoring diagnostic test values (aka Meter Verification) if required by the manufacturer.
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If after reading through this list you have any questions about your magnetic flow meter, reach out to your Emerson representative, contact us at www.emerson.com, or customer service at: 1 800-522-6277
