Safety Electromagnetic Flow Meter 20mA with PTFE/PFA/F46 Liner Material for DN200-DN400 pipe sizes. Designed for reliable flow measurement in industrial applications.

1. Flow Reading Fluctuates/Jumps (Most Common)
   Causes: Air bubbles in the pipe, insufficient pipe filling, poor grounding, electromagnetic interference
   • Air removal: Install at the low point of the pipeline or add an exhaust valve upstream
   • Full pipe: Install horizontally with electrodes on the side to avoid air accumulation at the top; install vertically with fluid flowing upward
   • Grounding: Use a dedicated ground wire with resistance <10Ω; install grounding rings for plastic/insulated pipes
   • 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
   • Ensure the pipeline is fully filled with no negative pressure
   • Check for reversed excitation and signal wires
   • Verify parameters such as meter diameter, measuring range, and units
   • Measure excitation coil resistance (normal: 80-150Ω)
3. Inaccurate Measurement (Over/Under Reading)
   Causes: Electrode fouling, damaged liner, insufficient straight pipe length, zero drift
   • Clean electrodes: Use a soft brush or dilute hydrochloric acid to remove insulating deposits
   • Inspect liner: Check for wear, bulges, or cracks
   • Straight pipe requirements: Upstream ≥10D, downstream ≥5D (D = pipe diameter)
   • 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
   • Re-establish reliable grounding to ensure equipotential connection
   • Clean electrodes and check insulation
   • Confirm medium conductivity >5μS/cm
   • Keep away from strong interference sources such as inverters and motors

• 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)