The Ins and Outs of Electromagnetic Flow Meters

Electromagnetic flow meters are a leading meter choice for recording the volume of flow of electrically conductive liquids in a wide range of industries, including chemical, pharmaceutical and water and wastewater treatment. Also frequently referred to as mag meters or magnetic meters, electromagnetic flow meters are proven to decrease system maintenance and improve accuracy, which makes them a common metering solution in many key applications. Keep reading for a comprehensive understanding of how these meters work, plus additional benefits.  

Electromagnetic Flow Meters Explained

Electromagnetic flow meters are volumetric flow meters that operate under the principle of Faraday’s Law of Electromagnetic Induction. They measure the velocity of flow as liquid passes through the meter during a set period of time. Electromagnetic meters are non-intrusive with a completely open flow tube design—which promotes uninhibited flow and reduces maintenance since there are no moving parts that wear out over time.

Key Benefits of Electromagnetic Flow Meters

Whether you’re looking to improve accuracy, decrease system maintenance or meet the demands of challenging liquid conditions, electromagnetic meters are a leading choice to deliver the performance and precision your applications require. Individuals choose electromagnetic meters for these key reasons:

• Accuracy readings up to +0.20% of the measured value, which is impressively accurate compared to some mechanical counterparts
• No moving parts or flow obstructions, which means virtually no maintenance or pressure drop
• Flow range turndown ratio up to 400:1 or better, providing wide flow range capabilities
• Available in many sizes to fit an array of pipe sizes ranging from ¼ in. up to 78 in.

How Electromagnetic Flow Meters Work

Every electromagnetic meter tube is lined with a non-conductive material like hard rubber, PTFE or something similar. On the exterior of the meter sits two DC-powered electromagnetic coils that are placed diametrically opposite of one another. Two measuring electrodes are inserted into the tube and placed perpendicular to the electromagnetic coils. A third electrode sits at the top of the liner to sense if the pipe is full. This calculated design creates a magnetic field across the entire pipe diameter due to the energized coils.

As a conductive fluid—like water—flows through the magnetic field, a voltage is induced across the two measuring electrodes. The resulting voltage magnitude is directly proportional to the average velocity of the fluid. The induced voltage is then amplified and digitally processed to produce an accurate digital or analog signal. This signal can then be used to indicate flow rate or totalization of fluid volume, or to communicate or interface with another piece of equipment.

Key Applications for Electromagnetic Meters

Electromagnetic meters are suitable options for a number of applications including:

• Drinking water, water and wastewater, well water and reclaimed water
• Irrigation
• Process water/semiconductor
• Chemicals
• Food
• Pharmaceutical/biotechnology
• HVAC
• Industrial
• Concrete batching
• Power generation

Selecting an Electromagnetic Meter for Your Application

Electromagnetic meters all function the same way but come in different sizes with different materials and features, so it’s important to work with a team who understands your application requirements. Look through our electromagnetic meter lineup or ask our experts for a recommendation. We’re happy to help you find the perfect solution for your unique application.