What is the Difference Between Magnetic Flow Meter and Vortex Flow Meter?

Magnetic flow meters (or electromagnetic flow meters) and vortex flow meters are both widely used for measuring flow rates in industrial applications, but they operate on different principles and are suited for different types of fluids and conditions. Here’s a breakdown of their key differences:

• Measurement Principle

Magnetic Flow Meter: Operates based on Faraday's Law of Electromagnetic Induction. It measures the flow of conductive fluids by detecting the voltage generated as the fluid flows through a magnetic field.

Vortex Flow Meter: Measures flow rate based on the Von Kármán effect. When a fluid flows past a bluff body (an obstruction), it creates alternating vortices downstream. The frequency of these vortices is proportional to the flow rate and is detected by sensors.

• Fluid Compatibility

Electromagnetic flowmeters are suitable for measuring the flow of conductive liquids, such as water, acid, alkali, salt water, sewage, etc. Since electromagnetic flowmeters do not need to contact the measuring medium, they can measure high viscosity, corrosive and easy-to-crystallize liquids. However, electromagnetic flowmeters have poor measurement effects on non-conductive liquids and gases.

Vortex flowmeters are suitable for measuring the flow of liquids and gases, but the measuring medium must have a certain fluidity and stability. Vortex flowmeters also have poor measurement effects on high viscosity, corrosive and easy-to-crystallize liquids.

Feature	Magnetic Flow Meter	Vortex Flow Meter
Suitable Fluids	Conductive liquids (e.g., water, wastewater, milk, juices, chemicals, slurries)	Liquids, gases, and steam
Minimum Conductivity	Requires ≥2 µS/cm conductivity	Works with both conductive & non-conductive fluids
Gas/Steam Measurement	Not suitable	Suitable

• Accuracy & Performance

The accuracy of electromagnetic flowmeters is usually between ±0.2% and ±0.5%, but the accuracy will be reduced when measuring low flow rates and small-diameter pipes. The accuracy of electromagnetic flowmeters is affected by factors such as the conductivity, temperature, pressure and flow rate of the measuring medium.

The accuracy of vortex flowmeters is usually between ±1% and ±1.5%, but the accuracy will be reduced when measuring low flow rates and small-diameter pipes. The accuracy of vortex flowmeters is affected by factors such as the density, viscosity, temperature and pressure of the measuring medium.

Feature	Magnetic Flow Meter	Vortex Flow Meter
Accuracy	High (±0.2% to ±0.5%)	Moderate (±0.5% to ±1.0%)
Pressure Loss	None (full-bore design)	Small pressure loss (due to bluff body)
Sensitivity to Flow Profile	Low (can handle turbulent or laminar flow)	High (needs stable flow, requires straight pipe runs)
Min. Flow Velocity	0.2 m/s	1.0 m/s

• Installation and Maintenance

Magnetic Flow Meter: Typically requires straight pipe sections upstream and downstream for optimal accuracy. However, it has no moving parts, which minimizes wear and tear, reducing maintenance requirements.

Vortex Flow Meter: Also requires straight pipe sections to maintain accuracy. It has moving parts, which can lead to wear and may need more frequent maintenance, especially in abrasive or contaminated fluids.

Feature	Magnetic Flow Meter	Vortex Flow Meter
Pipe Fullness Required?	Yes	Yes
Straight Pipe Requirement	5-10D upstream, 2-5D downstream	10-20D upstream, 5-10D downstream
Moving Parts?	No (low maintenance)	No (low maintenance)
Susceptibility to Vibration?	Low	High (vibration can cause inaccurate readings)

• Typical Applications

Magnetic Flow Meter: Commonly used in water treatment, chemical processing, and pulp and paper industries for liquid flow measurement.

Vortex Flow Meter: Often used in the energy industry, HVAC systems, and for steam, gas, and liquid applications where accuracy in turbulent flows is not critical.

Both types of meters provide valuable measurement options, with magnetic flow meters being better for conductive liquids and vortex flow meters being versatile for measuring both liquids and gases, especially under higher pressures and temperatures.