Magnetic flow meters are devices used to measure conductive liquids flow rate in a pipe or conduit. They are highly accurate and reliable, making them popular in various industries, including water treatment, chemical processing, and food and beverage production.
This article will provide a comprehensive guide on how magnetic flow meters work.
What are Magnetic Flow Meters?
Magnetic flow meters, also known as mag meters, use a magnetic field to measure the flow rate of a conductive fluid. They consist of a pipe or conduit, a magnetic field generator, and two electrodes placed perpendicular to the magnetic field.
The fluid flows through the pipe or conduit, and the magnetic field generator creates a magnetic field across the fluid flow.
As the fluid flows through the magnetic field, it induces a voltage in the electrodes proportional to the fluid flow rate. Learn more about Magnetic flow meters.
How Does a Magnetic Flow Meter Work?
Magnetic flow meters work based on Faraday’s law of electromagnetic induction, which relates force, magnetism and electricity, often called the right-hand rule . According to this law, a when a force is induced through a magnetic field, and electrical current proportional to force is produced. Force is flow, and by creating a magnetic field in a pipe or conduit a current/voltage output proportional to flow occurs. However the fluid (liquid) must be electrically conductive of no less than 3 microSiemens in order to generate a signal proportional to flow rate.
The voltage induced in the electrodes is proportional to the fluid flow rate. The voltage signal is then amplified and sent to a transmitter, which converts it into a flow rate reading.
Advantages of Magnetic Flow Meters
Magnetic flow meters offer several advantages over other types of flow meters, including:
High Accuracy
Magnetic flow meters are highly accurate and can accurately measure fluid flow rates within ±0.25%.
No Moving Parts
Magnetic flow meters have no moving parts, which means they have minimal maintenance requirements and can operate for long periods without the need for calibration.
Wide Range of Applications
Magnetic flow meters can measure the flow of a wide range of fluids, including liquids, gasses, and slurries, making them suitable for various industries and applications.
Bi-Directional Flow Measurement
Magnetic flow meters can measure fluid flow in both directions, making them ideal for applications where fluid flow direction changes frequently.
Limitations of Magnetic Flow Meters
While magnetic flow meters offer many advantages, they also have some limitations, including:
Conductive Fluids Only
Magnetic flow meters can only measure the flow rate of conductive fluids, which means they cannot be used to measure the flow rate of non-conductive fluids, such as hydrocarbons.
Pipe Size Limitations
Magnetic flow meters are typically only suitable for use in pipes or conduits with diameters of 1/2 inch or larger.
Installation Requirements
Magnetic flow meters require a straight pipe run before and after the meter to ensure accurate readings. They also require a power source to operate the magnetic field generator.
Conclusion
Magnetic flow meters are highly accurate and reliable devices used to measure the flow rate of conductive fluid. They work based on Faraday’s law of electromagnetic induction, where a voltage is induced in a conductor when it passes through a magnetic field.
Magnetic flow meters offer several advantages, including high accuracy, no moving parts, a wide range of applications, and bi-directional flow measurement. While they have some limitations, magnetic flow meters remain a popular choice in various industries and applications.
