What Is an Electromagnetic Flow Meter?
An electromagnetic flow meter (also called a mag meter or magmeter) measures the velocity of a conductive liquid flowing through a pipe using Faraday's Law of Electromagnetic Induction. When a conductive liquid flows through a magnetic field generated by the meter's coils, a voltage is induced that is directly proportional to the flow velocity. No moving parts are involved, making it extremely reliable and maintenance-free.
The key requirement: the liquid must be electrically conductive (minimum 5 μS/cm). This makes mag meters ideal for water, wastewater, slurry, and chemical solutions — but not for pure water, oils, or gases.
How an Electromagnetic Flow Meter Works
Inside the meter, two electrodes contact the liquid. A magnetic field is applied perpendicular to the flow direction. As the conductive liquid moves through the field, a voltage is generated between the two electrodes. The transmitter measures this voltage and converts it to a flow rate using the pipe cross-section area. The signal is sent to a display, PLC, or SCADA system via 4–20 mA or pulse output.
Key Applications in Water Treatment
- Inlet raw water metering — measuring intake from bore wells, rivers, or municipal supply
- Treated water flow — measuring flow out of WTP, STP, or RO plant
- Effluent discharge monitoring — mandatory in many CPCB/SPCB permits
- Chemical dosing lines — measuring chemical feed flow accurately
- Sludge flow measurement — tracking sludge volume to dewatering equipment
- Pump performance monitoring — detecting pump wear by comparing actual vs rated flow
Advantages Over Other Flow Meters
| Feature | Mag Meter | Turbine Meter | Ultrasonic Meter |
|---|---|---|---|
| Moving parts | None | Yes (rotor) | None |
| Accuracy | ±0.2–0.5% | ±0.5–1% | ±1–2% |
| Pressure drop | Zero | Moderate | Zero |
| Handles slurry? | Yes | No | Limited |
| Requires conductive fluid | Yes (>5 μS/cm) | No | No |
| Maintenance | Very low | Rotor cleaning/replacement | Low |
Electromagnetic Flow Meters from QuaSys
QuaSys Inc. supplies electromagnetic flow meters for water treatment, effluent, and industrial process applications. We can advise on liner material (rubber, PTFE, PFA), electrode material (SS316, Hastelloy, Titanium), and communication output (4–20 mA, HART, RS485 Modbus) for your specific application.
Call us at +91 11 29531287 or send an enquiry.
