Regular maintenance and inspection of electromagnetic flowmeters are essential for all users to ensure the smooth operation of daily production processes. These devices are widely used in industrial settings, particularly in the wastewater treatment industry, where they have accumulated significant experience in both use and maintenance. Here’s a detailed guide on how to properly maintain and inspect these meters:
Electromagnetic flowmeters are commonly used for flow control in industrial applications, especially when dealing with corrosive or abrasive fluids. In practice, failures often occur due to factors such as corrosion leakage, insulation degradation, electrode contamination, or foreign material adhesion. Identifying and addressing these issues early is crucial to prevent costly downtime.
The main goal of daily inspections is to confirm that the electromagnetic flowmeter is operating within acceptable limits. This can be done through online or offline checks, which help verify whether the meter's readings meet the expected measurement standards. Regular verification ensures accurate data collection and reliable process control.
Traditional periodic maintenance involves removing the flow sensor from the pipeline for inspection and calibration. To minimize damage to the lining, it's recommended to first measure the insulation resistance of the pipeline. If any abnormalities are detected, further inspection or calibration may be required.
For pipelines where the flow cannot be stopped, an online check can be performed to detect any anomalies. This includes testing the converter using a high-accuracy analog signal generator and checking the sensor by measuring the electrode's resistance and the excitation coil's insulation and copper resistance. Additionally, the excitation current output and magnetic field strength can be indirectly assessed. For systems where the flow can be stopped, the sensor area can be accessed to inspect for dirt, deposits, and cleaning if necessary.
It's also recommended to conduct a comprehensive annual inspection of the electromagnetic flowmeter. This includes visual checks, converter performance tests, calibration of measurement values, voltage measurements across different parts, insulation resistance testing, and circuit verification. Zero point adjustment is particularly important due to drift, but it must be done while the flow is stopped, which can be inconvenient. As a result, online inspections often skip this step and focus on converter calibration instead. Comparing results with historical data helps determine whether the device should continue to be used, repaired, or replaced. The condition of the sensor's insulation and excitation coil is also evaluated to decide on necessary updates.
