Electromagnetic flowmeter installation and maintenance


The measurement principle of electromagnetic flowmeter is Faraday's law of electromagnetic induction. The main components of the sensor are: measuring tube, electrode, excitation coil, iron core and yoke shell. It is primarily used to measure volume flow in conductive liquids and slurries in closed pipes. Including acid, alkali, salt and other highly corrosive liquids. The product is widely used in petroleum, chemical industry, metallurgy, textile, food, pharmaceutical, papermaking and other industries as well as environmental protection, municipal management, water conservancy construction and other fields. There are two types of faults in the operation of the electromagnetic flowmeter: one is the fault of the instrument itself, that is, the fault caused by the damage of the instrument structure or components; the other is the fault caused by external reasons.

  1. Common failures of electromagnetic flowmeters—the instrument has no flow signal output

  1. Cause Analysis

    This kind of fault is more common in the process of use, and the reasons are generally:

    (1) the power supply of the instrument is not normal;

    (2) the cable connection is not normal;

    (3) the liquid flow condition does not meet the installation requirements;

    (4) The sensor parts are damaged or there is an adhesion layer on the inner wall of the measurement;

    (5) The converter components are damaged.

  2. Solutions

    (1) Confirm that the power supply has been connected, check whether the output voltage of each circuit board of the power supply circuit board is normal, or try to replace the entire power supply circuit board to judge whether it is good or bad.

    (2) Check whether the cable is in good condition and whether the connection is correct.

    (3) Check the direction of liquid flow and whether the liquid in the tube is full. For the electromagnetic flowmeter that can measure forward and reverse, if the direction is inconsistent, it can be measured, but the set display flow direction does not match the positive and negative directions, and must be corrected. If the workload of removing the sensor is heavy, the direction of the arrow on the sensor can also be changed and the symbol of the displayed instrument can be reset. The pipeline is not full of liquid, which is mainly caused by the improper installation position of the sensor. Measures should be taken during installation to avoid the liquid in the pipeline from being full.

    (4) Check whether the electrodes on the inner wall of the transmitter are covered with a liquid scab layer. For the measurement liquid that is easy to scab, it should be cleaned regularly.

    (5) If it is judged that the fault is caused by the damage of the converter components, just replace the damaged components.

  3. Common faults of electromagnetic flowmeter - output value fluctuation

  4. Cause Analysis

    Most of these faults are caused by the influence of the measurement medium or the external environment, and the fault can be eliminated by itself after the external interference is eliminated. In order to ensure the accuracy of the measurement, such failures cannot be ignored. In some production environments, due to the large vibration of the measuring pipe or liquid, the circuit board of the flowmeter will be loosened, which may also cause fluctuations in the output value.

  5. Solutions

    (1) Confirm whether it is the cause of the process operation, and the fluid does pulsate. At this time, the flowmeter only reflects the flow status truthfully, and the fault can be eliminated by itself after the pulsation ends.

    (2) Electromagnetic interference generated by external stray currents, etc. Check whether there are large electrical appliances or electric welding machines working in the operating environment of the instrument, and confirm that the instrument is grounded and the operating environment is good.

    (3) When the pipeline is not filled with liquid or the liquid contains air bubbles, both are caused by technological reasons. At this time, you can ask the technical personnel to confirm. After the liquid is full or the bubbles calm down, the output value can return to normal.

    (4) The circuit board of the transmitter is a plug-in structure. Due to the large vibration of the on-site measurement pipeline or liquid, the power board of the flowmeter often becomes loose. If it is loose, disassemble the flowmeter and fix the circuit board again.

Electromagnetic Flow Meter

Electromagnetic flow meters are intended for fluid measurement in most industries including water, wastewater, food and beverage, pharmaceutical and chemical.

There are two basic components of electromagnetic flow meter: 

1) The Detector, which includes the flow tube, isolating liner and measuring electrodes, and 

2) The Converter, which is the electronic device responsible for signal processing, flow calculation, display and output signals.

The materials of construction of the wetted parts (liner and electrodes) should be appropriate for the specifications on the intended type of service. Review of the compatibilities consistent with the specifications is recommended.

Our electromagnetic flow meters are factory tested and calibrated. A calibration certificate is included in the shipment of each meter.

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