Electromagnetic flowmeter for measuring copper sulfate solution
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This post was last edited by Shining brightly_X1PWH on 2024-3-14 at 16:55. We are facing a problem at the customer’s site and would like to seek advice from those with more experience. The electromagnetic flowmeter is used to measure flow rate; the medium is a copper sulfate solution, the electrode material is tantalum, it has a grounding ring, and its diameter is DN65. There are dozens of meters on site, and currently two of them are showing inconsistent performance – the readings fluctuate greatly at times, while at other times they remain quite stable. I was wondering if anyone has encountered this situation? Could you help analyze what might be causing this phenomenon?
This description is a bit too general. Check the installation location and verify whether the fluid flow is stable ； Next, verify whether the grounding ring makes good contact with the meter body and the grounding electrode. Let’s take another look to see if the instrument parameters can be adjusted. With limited capabilities, I can only think of these three points
Maybe I didn’t explain myself clearly. I’ve already checked the wiring, grounding, and parameter settings; the installation location seems to be fine as well. On another production line using the same process, the gauge operates very stably, but this one works inconsistently.
Since it is a copper sulfate solution, copper ions may undergo weak or significant chemical reactions with the grounding electrode/grounding ring, but such reactions may require certain conditions of the medium to occur; this could be one of the reasons why the phenomenon appears intermittently. Also, is the ground electrode or grounding ring connected reliably? Copper sulfate solution is generally the feed solution used in the copper electrolysis process. Therefore, it is necessary to consider whether the strong direct current field in the electrolytic cell has a significant impact on the electromagnetic flowmeters located nearby, or to conduct on-site investigations to determine this. Furthermore, with the conventional single-excitation method, its performance in electrolysis processes is unsatisfactory due to the effects mentioned above, which is only logical. In contrast, electromagnetic flowmeters with dual-frequency excitation perform very well in any electrolysis process, such as those used in chlor-alkali production or electroplating.
Okay, thank you. What we provide to our customers are Yokogawa electromagnetic flowmeters with dual-frequency excitation. I visited the client’s site a few days ago and stayed for two days; since no abnormalities were found as the client had mentioned, I left. To my surprise, abnormalities reappeared during those two days. My judgment is that there should be no problem with the flow meter; it might be related to the medium used by the customer. That’s why I’d like to ask the experts in the chemical industry for their opinions.
What material is the user media pipeline made of? Is it made of pure engineering plastic, or is it a metal pipe with a lining? In the situation you described, it is very likely that the grounding electrode has not been connected properly in accordance with the requirements for connecting non-conductive pipelines; furthermore, it is necessary to check whether the electrode type used in the flow meter is appropriate. If it doesn’t work well all the time, it is possible to suggest that the user switch to Yokogawa’s capacitive electromagnetic flowmeters, namely the CA series of electromagnetic flowmeters
The customer’s pipeline is made of PVC, with a grounding ring; the measurement electrode is made of tantalum, and the grounding electrode is also made of tantalum. The customers have done it for grounding. It’s not practical to replace them, as dozens of such electromagnetic flowmeters were purchased for this project, and only these two have developed this issue.
This post was last edited by qugd on 2024-3-15 at 12:19. It is likely that there is leakage current in the medium pipeline; by installing two copper flange gaskets at both ends of the electromagnetic flowmeter, ensuring that these gaskets make good contact with the medium, and simultaneously providing reliable grounding for these copper gaskets, the problem should be resolved. The pressure isn’t high, so a graphite gasket should work as well. I guess the user is using PTFE gaskets or PVC gaskets
Okay, thank you for your advice. It seems the customer is using PVC gaskets. Yesterday, I suggested to the client that they check whether there is voltage at both ends of the flange, and make a bypass connection between those two ends.
The leakage current of the electrolyzer has a significant impact on electromagnetic flowmeters; sometimes, without a thorough examination of the actual conditions on site or without relevant field experience, it can be quite confusing.