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What Materials Are Used in the Electromagnetic Flow Meter Body?
In an electromagnetic flow meter, the body usually refers to the sensor assembly installed in the pipeline. It is not made from a single material, but from several structural and functional parts, including the measuring tube, liner, electrodes, housing, excitation coils, and coil frame.
These parts can be divided into two main groups: wetted parts and non-wetted parts. Wetted parts, such as the liner, electrodes, and sanitary process connections, directly contact the measured liquid. Non-wetted parts, such as the measuring tube, housing, excitation coils, and coil frame, do not contact the medium but still affect the sensor’s strength, magnetic field stability, and long-term performance.
Material selection depends on the process conditions, including medium corrosiveness, abrasion level, operating temperature, pressure rating, conductivity, and hygienic requirements. Below is a practical overview of the common materials used in electromagnetic flow meter bodies and how each material affects application performance.
1. Liner Materials
The inner wall of the measuring tube must be covered with an insulating liner. The liner prevents the conductive liquid from contacting the metal tube and ensures the electromagnetic flow meter can generate a stable measurement signal.
The selection of liner material depends mainly on corrosion resistance, abrasion resistance, temperature resistance, and process conditions.
PTFE
PTFE has good corrosion resistance and temperature resistance. It is suitable for most industrial applications, such as water treatment and chemical processing.
However, PTFE is not suitable for vacuum or negative-pressure conditions. When the pipeline is under vacuum, the PTFE liner may loosen or separate from the measuring tube.
ARTang electromagnetic flow meters used in water treatment and chemical applications commonly use PTFE liners.
PFA
PFA is suitable for strong acids, strong alkalis, highly corrosive chemical media, and high-temperature fluids.
ARTang sanitary electromagnetic flow meters for the food and beverage industry use PFA liners and are available with 3-A certification.
Polyurethane
Polyurethane, also known as PU, has excellent abrasion resistance. It is suitable for liquids containing solid particles, such as slurry, mud, and other abrasive media. For these applications, a slurry electromagnetic flowmeter with a wear-resistant liner is usually recommended.
Neoprene Rubber
Neoprene rubber has good wear resistance and is suitable for normal-temperature applications such as municipal water supply and tap water measurement.
Ceramic
Ceramic liners provide good abrasion resistance, corrosion resistance, and high-temperature resistance. They are suitable for harsh applications involving strong corrosion or heavy abrasion.
2. Measuring Tube Material
The measuring tube is the main structural part of the sensor. It must be made of non-magnetic material so that it does not affect the magnetic field generated by the excitation coils.
Common measuring tube materials include austenitic stainless steel, such as 304 stainless steel.
This material provides good structural strength and pressure resistance while maintaining the non-magnetic properties required for electromagnetic flow measurement.
3. Electrode Materials
The electrodes must have good electrical conductivity and must be compatible with the measured medium. Different electrode materials are selected according to the corrosiveness and chemical properties of the fluid.
Common electrode materials include:
316L Stainless Steel
316L is commonly used in water treatment, food processing, and many general industrial applications.
Hastelloy C
Hastelloy C is suitable for dilute sulfuric acid, phosphoric acid, organic acids, and high-temperature corrosive conditions.
Titanium
Titanium is suitable for seawater, high-salt wastewater, bleach, sodium hypochlorite, and other chlorine-containing media.
Tantalum
Tantalum has excellent resistance to many strong acids. It is suitable for hydrochloric acid, dilute hydrochloric acid, strong reducing acids, highly corrosive chemical media, and high-temperature strong acid applications.
Platinum-Iridium Alloy
Platinum-iridium alloy is suitable for complex highly corrosive media, high-concentration strong acids, mixed corrosive liquids, specialty chemical processes, and high-end pharmaceutical applications.
4. Sensor Housing Material
The housing is usually made of stainless steel or carbon steel.
For integrated electromagnetic flow meters, where the converter is directly mounted on the sensor, this type of housing structure is commonly used.
5. Excitation Coil Material
The electromagnetic flow meter sensor must contain excitation coils to generate the magnetic field required for measurement. These coils are usually made of copper wire.
Depending on the structure, excitation coils can be self-bonding or non-self-bonding. According to coil shape, they may be cylindrical, saddle-shaped, or other forms.
The excitation coil should have good heat resistance and should not deform easily, so that it can maintain a stable induced magnetic field during operation.
6. Coil Frame Material
The coil frame must be made of non-magnetic material with excellent electrical insulation properties.
It also needs good thermal stability and mechanical strength. This helps prevent deformation, expansion, or cracking during high-temperature operation or coil winding.
Common coil frame materials include engineering plastics, such as glass-fiber-reinforced nylon or polyester-based plastics.
Select the Right Materials for Stable Flow Measurement
In addition to the main components above, an electromagnetic flow meter sensor may also include gaskets, screws, sealing parts, and other accessories, depending on the magnetic circuit design and mechanical structure.
The sensor body has a direct impact on the overall performance of an electromagnetic flow meter. Reliable material selection, precise assembly, and proper structural design are all important for producing a stable and durable magnetic flow meter.
Need Help Choosing the Right Magmeter Material?
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