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Correctly find the steps and solutions for electromagnetic flowmeter failures

Author:vacorda    Source:vacorda.com    Date: 2018-03-12 16:56:24

Electromagnetic flowmeter as an effectively measure the volume flow rate of conductive media, its main components include sensors, flow conversion and processing instruments. And its main feature is that it has no throttling flow-resisting parts, it is not easy to block, has good corrosion resistance, and has a wide range of applicable media. The measurement accuracy is not affected by physical parameters such as temperature, viscosity, density, pressure, and specific gravity of the measured medium. A certain conductivity range is independent of the type of liquid being calibrated.

As a most widely used flow instrument, electromagnetic flowmeters are commonly used to measure conductive liquids such as tap water, sewage, and seawater. Therefore, after running for a period of time, it is easy to contaminate the electrode or to precipitate and foul in the measurement tube wall. So the adhered scale layer in the measuring tube of the electromagnetic flowmeter should be removed in time, otherwise the instrument may not work properly.

Intelligent electromagnetic flow meter

As a professional company specializing in the production of electromagnetic flowmeter, in the years of providing customers with the installation and maintenance process, Sichuan Vacorda Instrument summed up a set of most effective routine inspection of the electromagnetic flowmeter sensor:

1. Sensor inspection

The required test equipment: A multimeter, a 500MΩ insulation resistance tester.

Inspection steps:

  • When the pipeline is full of media, use a multimeter to measure the resistance value between terminals A, B, and C. The resistance between A-C and B-C should be approximately equal. If the difference is more than 1 time, it may be the leakage of the electrode, it has the adsorption of condensed water in the outer wall of the measurement tube or the junction box.
  • When the liner is dry, use insulation resistance tester to measure the insulation resistance between A-C and B-C (it should be greater than 200MΩ). Then use a multimeter to measure the resistance of the terminals A, B and the two electrodes in the measuring tube (it should be short-circuit connected). If the insulation resistance is very small, then the electrode leakage, the entire flowmeter should be returned to the factory for repair. If the insulation is reduced but there is still more than 50MΩ and the inspection result of step 3 is normal, the outer wall of the measuring tube may be damp, and the interior of the housing may be dried by a hot air blower.
  • With a multimeter to measure the resistance between X, Y, if more than 200Ω, the excitation coil and its lead wire may be open or poor contact. Remove the terminal board and check.
  • Check the insulation resistance between X, Y and C, should be more than 200MΩ, if there is a drop, use a hot air to dry the inside of the shell. In actual operation, a decrease in coil insulation will lead to an increase in measurement error and the unstable output signal of the instrument.
  • If it is determined that the sensor is faulty, contact the manufacturer of the electromagnetic flowmeter.

2. Conversion inspection:

 If it is determined that the converter is faulty, check with the manufacturer of the electromagnetic flowmeter if there is no problem with the external cause. The manufacturers generally adopt the method of replacing circuit boards.

3. The maintenance of the electrode

  • Before using the electromagnetic flowmeter, use a standard pH solution to calibrate the electromagnetic flowmeter. After the calibration, must clean the electrodes of the electromagnetic flowmeter with distilled water, and then use the test liquid to clean again.
  • When not use the electromagnetic flowmeter and remove its electrode, we must pay attention not to allow the touchpad of the electrode to collide with a hard object. Otherwise, it will affect the use of the electrode.
  • After the use of electromagnetic flowmeter, we must put the electrode sets to on the electrode, and put some saturated solution, as long as guarantee the electrode bulb is wet, but remember not to put it in distilled water.
  • Keep the electrode clean, do not let it appear the output short circuit on both sides, otherwise it will make the measurement is not accurate, affect the use of electromagnetic flowmeter.

Guanghua Rd, Qingyang Dist, Chengdu, Sichuan Province, China