When the flowmeter is put into operation or it is found that the instrument is not working properly after a period of normal operation, you should first check the external conditions of the flowmeter, such as whether the power supply is good, whether the pipeline is leaking or not full, whether there are air bubbles in the pipeline, and whether the signal cable is Damaged, whether the output signal of the converter (ie, the input circuit of the rear instrument) is open. Remember to blindly overhaul the flowmeter.
Sensor check
Test equipment: one 500MΩ insulation resistance tester and one multimeter.
Test steps:
(1) When the pipeline is full of medium, use a multimeter to measure the resistance between terminals A, B and C, and the resistance between A-C and B-C should be as large as equal. If the difference is more than 1 times, it may be due to leakage of the electrode, condensation water adsorption on the outer wall of the measuring tube or in the junction box.
(2) When the lining is dry, use a MΩ meter to measure the insulation resistance between A-C and B-C (should be greater than 200MΩ). Then use a multimeter to measure the resistance between terminals A and B and the two electrodes in the measuring tube (should be in a short-circuit connected state). If the insulation resistance is small, it indicates that the electrode is leaking. If the insulation has decreased but still more than 50MΩ and the inspection result of step (1) is normal, it may be that the outer wall of the measuring tube is damp, and a hot air blower can be used to dry the inside of the casing.
(3) Use a multimeter to measure the resistance between X and Y. If the resistance exceeds 200Ω, the excitation coil and its lead wires may be open circuited or in poor contact. Remove the terminal board for inspection.
(4) Check the insulation resistance between X, Y and C, it should be above 200MΩ, if it drops, dry the inside of the casing with hot air. In actual operation, the decrease of coil insulation will lead to increased measurement error and unstable output signal of the instrument.
(5) If it is judged that the sensor is faulty, please contact the manufacturer of the electromagnetic flowmeter. Generally, it cannot be solved on site, and it needs to be repaired by the manufacturer.
Converter check
If it is determined that the converter is faulty, if there is no problem after checking the external reasons, please contact the manufacturer of the electromagnetic flowmeter, and the manufacturer will usually solve it by replacing the circuit board.
Maintenance of electrodes
1. Before using the electromagnetic flowmeter, the electromagnetic flowmeter should be calibrated with a standard pH value solution. After calibration and before operation, you must pay attention to first clean the electrode of the electromagnetic flowmeter with distilled water, and then clean the electrode with the measuring liquid again.
2. If the electromagnetic flowmeter is not used, when removing the electrode of the electromagnetic flowmeter, everyone should be careful not to let the touch sensor of the electrode collide with the hard object, otherwise as long as there is damage, it will affect the use of the electrode.
3. After using the electromagnetic flowmeter, you should cover the electrode of the electromagnetic flowmeter, and put less saturated solution in it. Just make sure that the bulb of the electrode is wet, but remember not to put it in distilled water. soak.
4. Usually pay attention to keep the electrode clean, and do not make it short circuit on both sides of the output, otherwise it will make the measurement inaccurate and affect the use of the electromagnetic flowmeter.
In fact, there are still many ways to maintain the electrodes of the electromagnetic flowmeter. You should pay more attention during the use process, and do not cause the electromagnetic flowmeter to be unable to be used normally in the future because of your own little negligence.
