Case analysis of electromagnetic flowmeter error causes (4) - Database & Sql Blog Articles

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The problem caused by improper selection of the electrode and grounding ring material is caused by the mismatch between the material and the measured medium. The electromagnetic flowmeter that contacts the medium has an electrode and a grounding ring. The mismatch is not only the corrosion resistance problem, but also the electrode surface effect. . The surface effects should be: 1 chemical reaction (surface formation of blunt film, etc.); 2 electrochemical and polarization phenomena (potential generation); 3 catalyst action (molar formation on the electrode surface, etc.). Grounding rings also have these effects, but the impact is less.

Instance

4

Used in a chemical (smelting) plant in Shanghai

20

Yutai Hastelloy

B

The electrode electromagnetic flowmeter measures the hydrochloric acid solution with a higher concentration, and the output signal is unstable. On-site inspection confirms that the instrument is normal and excludes other causes of interference that may cause output sloshing. But in many other places, Hastelloy

B

The electrode meter works well when measuring hydrochloric acid. When it is analyzed whether the cause of the failure is caused by the difference in hydrochloric acid concentration, the judgment cannot be made because of the experience in the influence of the concentration of hydrochloric acid on the surface effect of the electrode. To this end, our factory and the use unit together use the chemical plant site conditions to do a real-flow test to change the concentration of hydrochloric acid. The concentration of hydrochloric acid is gradually increased. When the concentration is low, the output of the meter is stable. When the concentration is increased to

15

%~

20

When %, the meter output starts to shake. Concentration to

25

%, the output sway is as high as

20

%. After switching to the é’½ electrode electromagnetic flowmeter, it runs normally.


Shanghai Beverly Automation Technology Co., Ltd.