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Electromagnetic flowmeter fluid contact part of the material selection instructions

When I encounter an electromagnetic flowmeter, I believe that many users have problems with the selection of the type. For example, according to the flow selection, the material selection for the medium, plus some auxiliary functions, need to access the computer or the secondary meter. It is a more professional problem, which involves some calculation formulas and chemical knowledge. Today, we will talk about the aspects of electromagnetic flowmeter material selection that need attention.

Because the electromagnetic flowmeter has few components, simple shape and flexible material selection, the electromagnetic flowmeter can adapt to a variety of fluids. However, in the choice of materials, sensor components in contact with the fluid, such as the lining of the measuring tube, electrodes, grounding rings and gaskets, the corrosion resistance, wear resistance and operating temperature of various materials must be clearly understood. To adapt to different media.

First, the choice of lining material

Commonly used lining materials are fluoroplastics, rubber and polyurethane. Rubber is suitable for non-corrosive or weakly corrosive liquids such as industrial water, sewage and weak acids and bases. Fluoroplastics, which are PTFE linings, have excellent chemical resistance, but have poor wear resistance and cannot be used to measure slurry. Polyurethane has excellent wear resistance, but it is poor in acid and alkali resistance. Its wear resistance is 10 times that of natural rubber. It is suitable for coal slurry, pulp, etc., but the medium temperature is lower than 40-70 degrees Celsius. .

Second, the choice of electrode and grounding ring material

Measuring the corrosion resistance of the medium, the effect on the electrode is the most important factor to consider first. Commonly used metal materials, Ha B, Ha C, titanium, tantalum, platinum rhodium alloy, can cover almost all chemical liquids. In principle, the choice of electrode materials should be determined from the actual and previous experience of the application of the medium in other equipment. Sometimes necessary experiments are required, such as taking liquid samples on site to conduct corrosive experiments on materials in the laboratory.

The grounding ring is connected at both ends of the flow sensor of the pipeline. Their corrosion resistance requirements are lower than the electrode, and there is some corrosion, which can be replaced regularly. Stainless steel and Hastelloy are usually used. Due to the large volume, precious metals such as ruthenium platinum are less economically considered. If the process pipe is in contact with the fluid, no grounding ring is required.

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