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Common Trouble and Elimination Method of Electromagnetic Flowmeter

Author:vacorda    Source:vacorda.com    Date: 2016-11-07 15:21:38

There are main two common fault when electromagnetic flowmeter in the operation: First, the instrument itself failure, that instrument structure parts or components damage caused the failure; The second is caused by external causes of failure, such as improper installation flow changes, deposition and scaling and so on.


structure electromagnetic flow meter

No flow signal output


1. Cause Analysis : 

Such failures are more common in the use of the process, the reasons are generally:

(1) Instrument power supply is not normal;

(2) Cable connection is not normal;

(3) Liquid flow conditions do not meet the installation requirements;

(4) Damage to the sensor components or measuring the inner wall of the attached layer;

(5) Converter components damaged.

2. Solution:

(1) Check that the power is connected to the power supply, check the power supply circuit board output voltage is normal, or try to replace the entire power circuit board, determine its quality.

(2) Check the cable is intact, the connection is correct.

(3) Check the liquid flow direction and whether the liquid inside the tube is full.

(4) Check the transmitter inner wall electrode is covered with a liquid fouling layer, the liquid is easy to scale measurement, to regularly clean.

(5) If the converter component damage caused the failure, just replace it.



The output value fluctuations


1. Cause analysis:

Most of these failures are caused by the impact of measurement media or the external environment, the failures can be eliminated after the elimination of external interference. To ensure the measurement accuracy, such failures can not be ignored. In some production environments, due to the vibration of the measuring pipe or liquid, the flowmeter circuit board is loosened and caused the output value fluctuates.


2. Solution:

(1) Confirm whether the reasons for the operation of the process, the flow of fluid does occur, and now only to accurately reflect the flow of the flow meter, the fault can be eliminated after the end of the pulse.

(2) External stray current generated the electromagnetic interference. Check the instrument operating environment whether there is a large electrical or welding machine at work, you must confirm the instrument ground and operating environment is good.

(3) Pipeline is not full of liquid or the liquid containing bubbles, they are both the process causes. At this point you can request process personnel to confirm, until the liquid full the tube or the bubble calm, the output value can be restored to normal.

(4) Transmitter circuit board is the plug-in structure, due to the vibration of the measuring pipe or liquid, often resulting in loose power meter board. Such as loose, you can remove the flow meter, re-fixed the circuit board.



The flow measurement does not match the actual value


1. Cause Analysis:

Such failures are generally caused by the following circumstances: 

(1) Whether the transmitter circuit board intact;

(2) When the liquid flow rate is too low, the measured liquid contains small bubbles, bubbles rise and gradually gathered above the pipeline. Cause the liquid flow area changes, finally affect the measurement accuracy;

(3) The signal cable occur bad connection phenomenon or the cable insulation performance caused the inaccurate measurement ;

(4) The parameter settings are not accurate of the converter.


2. Solution:

(1) Check whether the transmitter circuit board is intact. If the junction box has water or be corroded by corrosion liquid, now you should replace the circuit board.

(2) Ensure that the flow rate of measured liquid in the pipeline above the minimum flow threshold value, so that the transmitter can work properly.

(3) Check whether the signal cable connections and cable insulation is intact, if the signal cable loose, then re-connect it; if the cable insulation is not in line with insulation requirements, you need to replace the new cable.

(4) Reset the converter settings, and verify the zero point, full-scale value of the converter.

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