Electromagnetic flow meters, also called mag meters, are widely used in industries such as water treatment, chemical processing, and food production. They are highly accurate, durable, and contain no moving parts. In this article, we’ll explain how electromagnetic flow meters work, their main components, and when they should (and shouldn’t) be used.

If you’re looking for a complete guide to selecting a mag meter, check out our step-by-step flow meter selection article.

1. Based on Faraday’s Law of Electromagnetic Induction

Mag meters operate based on Faraday’s Law, which states:

The voltage induced in a conductor moving through a magnetic field is proportional to its velocity.
Learn more about Faraday’s Law on Wikipedia

In a mag meter:

• The conductor = the fluid flowing through the pipe
• The magnetic field = created by coils on the flow tube
• The voltage = detected by electrodes on the pipe wall

Flow calculation formula:
E = k × B × D × V

Where:

• E: Voltage
• B: Magnetic field strength
• D: Distance between electrodes
• V: Velocity of fluid
• k: Constant based on geometry

2. Key Components of a Mag Meter

You can build a better understanding of the device by learning its core parts:

📌 Tip: Choose the liner and electrode materials according to the chemical nature of your fluid.

3. What Fluids Can Be Measured?

Electromagnetic flow meters only measure conductive fluids.
They work with:

• Water (raw, clean, or wastewater)
• Acids and bases
• Slurries, pulps, or mud
• Sewage and chemicals

They cannot measure:

• Oil or petroleum-based liquids
• Air, gas, or steam
• Ultra-pure deionized water

4. Pros and Cons

✅ Advantages:

• No moving parts – minimal maintenance
• High accuracy (±0.5% or better)
• Suitable for large pipe diameters
• Independent of pressure, viscosity, and temperature

❌ Limitations:

• Requires a fully filled pipe
• Cannot measure non-conductive fluids
• Sensitive to incorrect installation (e.g., poor grounding)

Need more technical specs? Visit Omega’s flow meter accuracy reference

5. Where Are Mag Meters Used?

Mag meters are found in:

• Drinking water supply networks
• Wastewater treatment systems
• Mining and pulp industry
• Food and beverage lines
• Chemical batching systems

They are especially useful in harsh or corrosive environments.

❓ Frequently Asked Questions (FAQs)

Q1: Can electromagnetic flow meters work with plastic pipes?
✔️ Yes, if the flow tube is properly grounded and the fluid is conductive.

Q2: What happens if there are air bubbles in the pipe?
⚠️ Air can interfere with readings. Deaerators or bubble traps are recommended.

Q3: Do mag meters need regular calibration?
🔧 Usually once every 12–24 months, depending on application criticality.

✅ Conclusion

An electromagnetic flow meter offers a reliable and highly accurate method to measure flow in conductive liquids. When correctly installed and maintained, it can deliver consistent results for years with minimal attention.

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Looking for the best electromagnetic flow meter for your industry?
Contact us today or explore our range of Mag Meters.