Functions of Each Part of Electromagnetic Flowmeter

The measuring principle of an electromagnetic flowmeter is based on Faraday’s law of electromagnetic induction. It is mainly used to measure the volumetric flow of conductive liquids and slurries in closed pipelines, including strongly corrosive fluids such as acids, alkalis, and salts. As we know, an electromagnetic flowmeter generally consists of several key components: a magnetic circuit system (excitation coils), a measuring tube, electrodes, a housing, a liner, and a converter.The measuring principle of an electromagnetic flowmeter is based on Faraday’s law of electromagnetic induction. It is mainly used to measure the volumetric flow of conductive liquids and slurries in closed pipelines, including strongly corrosive fluids such as acids, alkalis, and salts. As we know, an electromagnetic flowmeter generally consists of several key components: a magnetic circuit system (excitation coils), a measuring tube, electrodes, a housing, a liner, and a converter.

Main Components of an Electromagnetic Flowmeter

1. Magnetic Circuit System:

Its function is to generate a uniform DC or AC magnetic field. A DC magnetic circuit is usually achieved with permanent magnets, which has a simple structure and minimal interference from alternating magnetic fields. In electrolytic liquids, polarization can occur: the positive electrode becomes surrounded by negative ions, and the negative electrode by positive ions. This increases the internal resistance between the electrodes, which can severely affect the normal operation of the instrument.

2. Measuring Tube:

The measuring tube allows the conductive liquid to flow through. To prevent magnetic flux leakage or short-circuiting, the tube must be made of non-magnetic, low-conductivity, low-thermal-conductivity materials with high mechanical strength. Common materials include non-magnetic stainless steel, fiberglass, high-strength plastics, and aluminum.

3. Electrodes:

Electrodes are used to sense and measure the induced voltage signal proportional to the flow. They are typically made of non-magnetic stainless steel and must be flush with the liner to ensure unobstructed flow. Electrodes should be installed in a vertical orientation within the pipeline to prevent sediment buildup, which could reduce measurement accuracy.

4. Housing:

The housing is designed for waterproofing, dust protection, and corrosion resistance to ensure reliable long-term operation in harsh environments. In industries such as chemical processing or food production, flow meters are often exposed to corrosive fluids, making the housing material and protection rating critical. Common housing materials include stainless steel and aluminum alloys.

5. Liner:

The liner provides complete electrical insulation on the inner wall of the measuring tube and the flange sealing surfaces. It is in direct contact with the measured liquid and serves to enhance corrosion resistance while preventing the induced voltage from being short-circuited by the metal tube. Most liners are made from corrosion-resistant, high-temperature, and wear-resistant materials such as PTFE or ceramic.

6. Converter:

The induced voltage generated by the flowing liquid is very weak and susceptible to interference. The converter amplifies the induced signal, converts it into a standardized output signal, and suppresses major interference. Its function is to take the induced voltage detected by the electrodes (Ex) and amplify it into a standardized DC signal suitable for measurement and control systems.

As a precise flow measurement instrument, the electromagnetic flowmeter relies on the proper design and coordination of its components to ensure measurement accuracy and stability. The precise integration of the sensor, signal processing module, converter, power supply, and housing enables the flow meter to provide accurate and reliable measurements even in complex industrial environments.