Sulfuric acid flowmeter maintenance and care

It is only necessary to conduct periodic visual inspections of the instrument, check the environment around the instrument, remove dust and dirt, ensure that no water or other substances enter, check whether the wiring is in good condition, and check whether there are new strong electromagnetic field equipment near the instrument or new wires crossing the instrument.

If the measurement medium is easy to contaminate the electrode or precipitate or scale in the wall of the measurement tube, it should be descaled and cleaned regularly.

2. Fault finding

If the flow meter is found to be working abnormally after it has been put into operation or has been put into normal operation for a period of time, you should first check the external conditions of the flow meter, such as whether the power supply is good and whether the pipeline is in good condition. Whether there is leakage or the pipe is not full, whether there are bubbles in the pipe, whether the signal cable is damaged, whether the converter output signal (ie, the input circuit of the rear instrument) is open circuit. Remember to disassemble and repair the flow meter blindly.

3. Sensor inspection

Testing equipment: a 500MΩ insulation resistance tester and a multimeter.

Test steps:

(1) When the pipe is filled with medium, use a multimeter to measure the resistance between terminals A, B and C, and the resistance between A-C and B-C. The resistance values ​​should be large enough to be equal. If the difference is more than 1 time, it may be that the electrode is leaking or there is condensed water adsorbed 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 of terminals A and B and the two electrodes in the measuring tube (it should be in a short-circuit state). If the insulation resistance is very small, it means the electrode is leaking, and the entire flow meter should be returned to the factory for repair. If the insulation has declined but is still above 50MΩ and the inspection result in step (1) is normal, the outer wall of the measuring tube may be 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 it exceeds 200Ω, the excitation coil and its lead wire may be open circuit or have poor contact. Remove the terminal board and inspect.

(4) Check the insulation resistance between X, Y and C. It should be above 200MΩ. If it drops, use hot air to dry the inside of the shell. During actual operation, the reduction in coil insulation will lead to increased measurement errors and unstable instrument output signals.

(5) If it is determined that the sensor is faulty, please contact the electromagnetic flowmeter manufacturer. Generally, it cannot be solved on site and needs to be repaired at the manufacturer.

4. Converter inspection

If it is determined that the converter is faulty and there are no external causes, please contact the electromagnetic flowmeter manufacturer. The manufacturer will generally replace the circuit. Solved by board method.