Electromagnetic flowmeter maintenance and installation precautions
Author:vacorda Source:vacorda.com Date: 2018-08-15 15:51:54
1. Routine maintenance
Visually inspect the instrument for periodic inspection, check the surrounding environment of the instrument, remove dust, ensure that there is no other substance in the water, check whether the wiring is good, check whether there is a new strong electromagnetic field device near the instrument or a new cable meter. If the measuring medium is easy to contaminate the electrode or precipitate or scale in the measuring tube wall, it should be regularly cleaned and cleaned.
2. Fault finding
After the flowmeter starts to be put into operation or is put into operation for a period of time, it is found that the instrument is not working properly. You should first check the external condition of the flowmeter, such as whether the power supply is good, whether the pipeline is leaking or is in a non-full-tube state, and there are air bubbles in the pipeline. Whether the signal cable is damaged or not, and whether the converter output signal (ie, the rear instrument input circuit) is open. Remember to blindly disassemble the flowmeter.
3. Sensor inspection
Test equipment: one 500MΩ insulation resistance tester, one multimeter.
(1) In the case where the pipe is filled with medium, use a multimeter to measure the resistance between terminals A, B and C. The resistance between A-C and B-C should be equal. If the difference is more than 1 time, there may be leakage of the electrode, condensation on the outer wall of the measuring tube or inside the junction box.
(2) Under the condition of lining drying, the insulation resistance between A-C and B-C (should be greater than 200 MΩ) is measured by MΩ meter. Then use a multimeter to measure the resistance of the two electrodes in terminals A and B and the measuring tube (should be in short-circuit communication). If the insulation resistance is small, indicating that the electrode is leaking, the entire flowmeter should be returned to the factory for repair. If the insulation is reduced but there is still more than 50 MΩ and the inspection result of step (1) is normal, it may be that the outer wall of the measuring tube is damp, and the inside of the outer casing can be dried by a hot air blower.
(3) Use a multimeter to measure the resistance between X and Y. If it exceeds 200 Ω, the excitation coil and its lead wire may open or contact poorly. Remove the terminal block check.
(4) Check the insulation resistance between X, Y and C, which should be above 200 MΩ. If it is lowered, use hot air to dry the inside of the casing. In actual operation, the decrease in the insulation of the coil causes the measurement error to increase and the signal output from the meter to be unstable.
(5) If it is determined that the sensor is faulty, please contact the manufacturer of the electromagnetic flowmeter. The general site cannot be solved and needs to be repaired by the manufacturer.
4. Converter check
If it is determined that the converter is faulty, if there is no problem in checking the external cause, please contact the manufacturer of the electromagnetic flowmeter, and the manufacturer will generally solve the problem by replacing the circuit board.
1. Try to avoid ferromagnetic objects and equipment with strong electromagnetic fields, so as to avoid the magnetic field affecting the working magnetic field of the sensor and the flow signal.
2, should be installed in a dry and ventilated place, to avoid sun and rain, the ambient temperature should be -20 ~ +60 ° C, relative humidity is less than 85%.
3. There should be plenty of space around the flowmeter for easy installation and maintenance.
The measurement principle of the electromagnetic flowmeter is that it does not depend on the flow characteristics. If there is a certain turbulence and vortex inside the pipeline, it will be generated in the non-measurement zone (such as elbow, tangential current limit or half-opening shut-off valve upstream). Measurement is irrelevant. If steady-state eddy currents in the measurement zone affect the stability of the measurement and the accuracy of the measurement, then some measures should be taken to stabilize the flow rate distribution:
A. Increase the length of the straight pipe before and after.
B. Using a flow stabilizer.
C. Reduce a section of the measuring point.
Sichuan Vacorda Instruments Manufacturing Co., Ltd
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