Electromagnetic flowmeter troubleshooting includes verifying power and wiring, assessing fluid conductivity, inspecting electrode condition, calibrating for precision, and addressing interference or grounding issues to ensure accurate measurements.
How to check the flowtube of an electromagnetic flowmeter?
To check the flowtube of an electromagnetic flowmeter, follow these steps:
Check Coil Resistance
Disconnect the flowtube from the flowmeter electronics to ensure safety.
Using a multimeter, set it to the resistance (ohms) measurement mode.
Measure the resistance across the coil terminals, typically labeled as Coil+ and Coil-. The resistance should typically be within the manufacturer’s specified range, which can vary depending on the flowmeter model but is usually between 100 and 1,000 ohms.
Check Electrode Resistance
Make sure the flowtube is filled with water or a conductive fluid.
Disconnect the flowtube from the flowmeter electronics.
Using a multimeter set to the resistance (ohms) measurement mode, measure the resistance between the two electrode connections.
The resistance reading should typically fall within the range of 3 to 50 kilohms (3,000 to 50,000 ohms). If it’s outside this range, it may indicate electrode contamination or coverage, which can affect the accuracy of the flowmeter.
Examine the connection between the terminal block and the internal electrode for continuity. Resistance must be less than one ohm. This is due to the electrodes being directly attached to terminal block connections.
Check Signal Wiring Connection
Ensure the flowmeter electronics are powered off.
Inspect the signal wiring connections, including the wiring to the SIG1, SIG2, and SIG GND terminals.
Make sure all connections are secure and free from damage.
If there are any loose or damaged connections, correct them as needed.
Test for Alarms
Connect the terminal SIG1, SIG2, and SIG GND as instructed by the manufacturer.
Power on the flowmeter electronics.
If there was an alarm display related to fluid bubbles, it should disappear when the signal terminals are connected. This confirms that the converter is functioning normally.
Electromagnetic Flowmeter Troubleshooting Guide
The table below serves as a starting point for diagnosing typical issues with electromagnetic flowmeters, including possible causes and solutions. Additional diagnostics and processes may be required depending on the specific model and circumstances.
Symptom 1: Significant flow variations
Possible cause
Solutions
There are too many air bubbles or particles in the medium at the moment
Alteration made to install in a vertical orientation
medium’s conductivity is unequal or near the middle value
Change the installation location or choose a different model
A failure in the split line.
Look over the split cable before selecting a cable with strong shielding
Sensor insulation deteriorates
Return to the factory for repair
The electrode is either rusted or covered in dirt.
Electrodes need to be inspected and cleaned.
Incorrect damping value set
Adjust the damping time
Rapid changes in fluid velocity
Consider using a flow straightener to stabilize flow
Pipe vibrations or turbulence
Reinforce pipe installation to reduce vibrations
Electromagnetic interference
Shield cables and avoid nearby electrical equipment
Faulty grounding
Verify and improve grounding as required
Symptom 2: Flow rate indication is unstable
Possible cause
Solutions
Problem with the grounding
Check that the meter is correctly grounded to a reliable earth ground.
Air or gas entrapped in the fluid
Ensure proper degassing or venting of the fluid
obstruction of a pipeline.
Ensure that the pipes are clear by inspecting and cleaning them regularly.
Location of the converter away from areas with electrical interference.
Ensure that the converter is not placed in a location that is too close to potential sources of electrical interference.
Slurry conductivity variations in medium
Use robust electrode materials, clean or replace.Reconfigure flow meter settings for slurry characteristics
Abrasive or adhesive nature of slurry
choose appropriate electrode materials and clean regularly
Inadequate electrode material selection
Consult with manufacturer to select suitable electrodes
Symptom 3: Empty Pipe alarm
Possible cause
Solutions
No fluid flow in the pipe
Verify that there should be flow in the pipe.
Flow velocity below the flowmeter’s minimum detection
Check the flowmeter’s minimum velocity specification.
Air or gas pockets in the fluid
Ensure proper degassing or venting of the fluid.
Electrode issues (fouling or damage)
Inspect and clean or replace electrodes as necessary.
Faulty sensor or signal processing unit
Replace the faulty components
The conductivity of the fluid is minimal.
Replace it with a different type of flowmeter.
Symptom 4 No Power/No Display
Possible cause
Solutions
Faulty power supply
Ensure that the power supply and connections are correct.
Either the fuse has blown or the circuit breaker has tripped.
Either replace the fuse or the breaker and turn it back on.
Problems with the wiring
Perform any necessary inspections and rewirings.
Defective electronics within the flowmeter
Replace the defective electronics
LCD displays have far inadequate contrast.
Raise the level of contrast.
Symptom 5: Coil alarm
Possible cause
Solutions
Coil circuit malfunction
Check the integrity of the coil and its connections.
Open circuit in the coil
Replace the flowtube or flowmeter
Electrical wiring issues
Inspect and rewire the coil electrical connections as needed.
Faulty power supply
Ensure a stable and adequate power supply.
Electromagnetic interference
Shield cables and avoid nearby electrical equipment.
Faulty grounding
Verify and improve grounding as required.
Sensor or coil damage due to abrasive materials
Protect the sensor or coil from abrasive materials.
Symptom 6: Inaccurate Flow Rate Indication
Possible cause
Solutions
Electrode fouling or scaling
Clean or replace electrodes as necessary.
Incorrect electrode material selection
Ensure electrode material is suitable for the fluid.
Calibration drift
Re-calibrate the flowmeter for accurate readings.Regularly re-calibrate the flowmeter for accuracy.
Pipe vibrations or turbulence
Stabilize the installation to minimize vibrations
Electromagnetic interference
Shield cables and avoid nearby electrical equipment.
Changes in fluid properties (e.g., temperature)
Compensate for changes if necessary.
Electrode wear
Monitor electrode condition and replace when necessary.
Aging or degradation of flowmeter components
Perform regular maintenance and replace worn parts.
By clicking on the link that is provided below will take you to the procedure for calibrating the electromagnetic flow meter.
