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Some common problems in the application of electromagnetic flowmeters

First, some common fault analysis of intelligent electromagnetic flowmeters in use, some are faults caused by damage to the components of the instrument itself, some are faults caused by improper selection, improper installation, environmental conditions, fluid characteristics, etc., such as display fluctuation, accuracy Drop or even instrument damage. It can generally be divided into two types: intelligent electromagnetic flowmeters, faults that occur during installation and commissioning, and faults that occur during normal operation.

Second, the commissioning period failure Debugging expectation failure generally occurs in the instrument installation and commissioning phase, once excluded from the same conditions will not appear again. Common commissioning failures are often caused by improper installation, environmental disturbances, and fluid characteristics.
1. The installation aspect is usually the fault caused by the incorrect installation position of the intelligent electromagnetic flowmeter sensor. Commonly, the sensor is installed at the highest point of the pipe that is easy to accumulate gas; or it is installed on the vertical pipe from top to bottom, and the row may appear. Empty; or no back pressure after the sensor, the fluid is directly discharged into the atmosphere to form a non-full tube inside the measuring tube.
2, the environmental aspects are usually mainly pipeline stray current interference, space strong electromagnetic wave interference, large-scale motor magnetic field interference. Pipe stray current interference usually takes good single ground protection to obtain satisfactory results, but if you encounter strong stray current, you need to take additional measures and flow sensor and pipe insulation. Space electromagnetic interference is typically introduced via a signal cable and is typically protected by a single or multiple layers of shielding.
3, the fluid aspect of the measured liquid contains evenly distributed tiny bubbles usually do not affect the normal operation of the intelligent electromagnetic flow meter, but as the bubble increases, the instrument output signal will fluctuate, if the bubble is large enough to cover the entire electrode surface At the same time, as the bubble flows through the electrode, the electrode circuit is momentarily broken and the output signal appears more fluctuating. When the low-frequency square wave excitation intelligent electromagnetic flowmeter measures the solid content of too much slurry, it will also generate slurry noise, causing the output signal to fluctuate. When measuring mixed media, if the flow sensor is measured before the mixing is not uniform, the output signal will also fluctuate. Improper matching of the electrode material and the measured medium will also affect normal measurement due to chemical action or polarization. The electrode material should be properly selected according to the instrument selection or related manual.

Third, the operating period failure The operating period failure is a fault that occurs after the intelligent electromagnetic flowmeter has been commissioned and operated for a period of time. Common operating period failures are generally caused by factors such as the adhesion layer on the inner wall of the flow sensor, lightning strikes, and changes in environmental conditions.
1. Adhesive layer on the inner wall of the sensor Since the intelligent electromagnetic flowmeter is commonly used to measure the dirty fluid, after running for a period of time, the adhesive layer often accumulates on the inner wall of the sensor and causes a malfunction. These failures are often caused by the electrical conductivity of the adhesion layer being too large or too small. If the attached material is an insulating layer, the electrode circuit will be broken and the meter will not work normally. If the conductivity of the adhesive layer is significantly higher than the fluid conductivity, the electrode circuit will be short-circuited and the meter will not work properly. Therefore, the adhesion scale layer in the measuring tube of the intelligent electromagnetic flowmeter should be removed in time.
2, lightning strikes Lightning strikes easily induce high voltage and surge current in the instrument line, making the instrument damaged. It is mainly introduced through the power line or the excitation coil or the flow signal line between the sensor and the converter, especially from the control room power line.
3. Changes in environmental conditions During the commissioning period, due to the good environmental conditions, the flowmeter works normally. At this time, it is easy to neglect the installation conditions. In this case, once the environmental conditions change, a new source of interference occurs during operation, which will interfere with the normal operation of the meter, and the output signal of the flow meter will fluctuate.

Fourth, the intelligent electromagnetic flowmeter in the process of use, there may be a variety of faults, but in general, all faults can be attributed to two types, that is, commissioning period failure and runtime failure, as long as we are in daily work Always pay attention to these two types of faults, and well to solve the problem, I believe that the intelligent electromagnetic flowmeter must be able to play its due role.

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