The Yokogawa electromagnetic flowmeter experiences large fluctuations in instantaneous flow rate
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The situation on site is as shown in the diagram: it’s a Yokogawa Axf015g electromagnetic flowmeter with a diameter of 15, used for handling strong acids. Tantalum electrodes were selected for use. For the first few days after installation, there were no fluctuations, but recently the fluctuations have become significant, ranging from -50 to 100. When the valve is closed, the flow rate gradually returns to zero, but minor fluctuations still occur. According to the manual, there might be issues with the installation, but many installations at the factory were done in this way without any fluctuations. If the pipes need to be modified, how should it be done? Should it be modified according to Diagram 1 or Diagram 2?
We haven’t connected it to ground either; I temporarily connected a grounding wire from another source, and there’s still fluctuation, so it’s probably not a grounding issue
In principle, with a pipe diameter of 15 mm, flow starvation generally does not occur. But the pipeline is still likely to be somewhat significantly affected by gravity flow. All that’s needed is to make an inverted U-shaped bend at the pipeline outlet. Additionally, grounding must be present and its effectiveness must be reliable.
1. You can try turning down the valve downstream. 2. The flow requirement is to have a full pipe; both 2 and 3 can achieve a full pipe. 3. Since it can be modified, why not install the flow meter on a vertical pipe where the medium flows upward?
Check the grounding; it is preferable to install the flow meter on a vertical pipe, with liquid entering at the bottom and exiting at the top
Grounding is usually something considered only when it doesn’t work, and it generally doesn’t have much effect
Is it the strong acid sludge that has clogged the measurement electrode?:o
Could the process piping react with strong acids and affect the measurements?
Let me tell you: just ensure the ground connection is proper. Connect the shielding layer of the control cabinet to the instrument ground wire; do not connect the shielding to the ground wire on-site