Safety Electromagnetic Flow Meter 20mA PTFE/PFA/F46 Liner Material DN200-DN400

Common Problems and Solutions for Electromagnetic Flow Meters

1. Flow Reading Fluctuates/Jumps (Most Common)

Causes: Air bubbles in the pipe, insufficient pipe filling, poor grounding, electromagnetic interference
Solutions:

1. Air removal: Install at the low point of the pipeline or add an exhaust valve upstream.

2. Full pipe: Install horizontally with electrodes on the side to avoid air accumulation at the top; install vertically with fluid flowing upward.

3. Grounding: Use a dedicated ground wire with resistance <10Ω; install grounding rings for plastic/insulated pipes.

4. Anti-interference: Route signal cables away from power cables and ground the shielding layer at one end only.

2. No Flow Reading/Zero Display

Causes: Empty pipe, reversed wiring, excitation/electrode failure, incorrect parameters
Solutions:

1. Ensure the pipeline is fully filled with no negative pressure.

2. Check for reversed excitation and signal wires.

3. Verify parameters such as meter diameter, measuring range, and units.

4. Measure excitation coil resistance (normal: 80–150Ω).

3. Inaccurate Measurement (Over/Under Reading)

Causes: Electrode fouling, damaged liner, insufficient straight pipe length, zero drift
Solutions:

1. Clean electrodes: Use a soft brush or dilute hydrochloric acid to remove insulating deposits.

2. Inspect liner: Check for wear, bulges, or cracks.

3. Straight pipe requirements: Upstream ≥10D, downstream ≥5D (D = pipe diameter).

4. Zero calibration: Perform zero calibration when the pipe is full and static.

4. Zero Drift/Negative Reading with Flow

Causes: Poor grounding, contaminated electrodes, low medium conductivity, interference
Solutions:

1. Re-establish reliable grounding to ensure equipotential connection.

2. Clean electrodes and check insulation.

3. Confirm medium conductivity >5μS/cm.

4. Keep away from strong interference sources such as inverters and motors.

5. Routine Maintenance (Preventive Measures)

- Clean electrodes regularly to prevent fouling coverage.

- Maintain full pipe condition with no air bubbles or negative pressure.

- Ensure reliable grounding, separate from motor/pipe grounding.

- Route signal and power cables separately.

- Perform zero calibration regularly (every 3–6 months).