Reasons for fluctuations in the output of sewage flow meters and countermeasures
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Among the common problems of sewage flow meters, those that occur during the commissioning phase are usually caused by installation issues or improper selection, whereas problems that arise during normal operation are generally due to changes in operating conditions or the emergence of new interference sources. Therefore, problems that occur during normal operation can generally be attributed to the instrument’s resistance to interference. Below is a brief analysis of the causes of fluctuations in the output of insert-type electromagnetic flowmeters and the corresponding solutions:I. Causes of the fault:
The fluctuations in output can generally be attributed to five main causes, as follows:
(1) The flow itself is fluctuating or pulsating; this is not actually a fault of the electromagnetic flowmeter, but rather a reflection of the actual flow conditions.
(2) The pipeline is not fully filled with liquid, or the liquid contains bubbles.
(3) External electrical and magnetic interference such as stray currents.
(4) Issues related to the physical properties of the liquid (such as uneven conductivity of the liquid or slurries containing many variable particles/fibers).
(5) Incompatible electrode materials with the liquid. II. Inspection procedure: For the situation of fluctuating output from the sewage flow meter, first conduct a preliminary investigation and assessment based on the flowchart, and then carry out detailed checks one by one to troubleshoot the issues. The sequence principle for the inspections listed in the process is as follows: ① Those that can be determined through observation or questioning without requiring extensive procedures come first, that is, start with the easier tasks first; ② Those that occur frequently based on past field maintenance experience and are likely to occur again in the future are prioritized; ③ The sequential requirements of the inspections themselves. If the causes of these faults are confirmed through a preliminary investigation, a detailed inspection can also be carried out in advance. Flow metering is one of the components of measurement science and technology, and it is closely related to the national economy, national defense construction, and scientific research. Doing this job well plays an important role in ensuring product quality, improving production efficiency, and promoting the development of science and technology. Especially in today’s era of energy crises and an increasing degree of automation in industrial production, the significance and role of flow meters in the national economy have become even more evident.
"Is flow itself a fluctuation or pulsation? Gagaga, whether it’s fluid fluctuations or pulsations, no matter how the fluid fluctuates or pulses, it remains a continuous liquid with no gaps. So how is it possible for the flow rate of a fluid to change significantly from one second to the next? Bro, I see that the flow meter’s readings are fluctuating wildly; find some other reason for that. Don’t blame the \"fluid itself\" – it doesn’t make sense. If your tool isn’t sharp enough, don’t blame your pants for not providing proper support; it doesn’t work that way, get it?
That makes sense! I recently installed a new electromagnetic flowmeter for measuring wastewater; the pump’s rated flow rate is 12.5 m3/h, but the value measured by the flowmeter is between 22 and 25 m3/h. Communicating with the manufacturer meant having to redo the grounding work, add grounding rings before and after the flow meter – it was still the same situation ； I took it apart and sent it back to the manufacturer for testing; they said there was no problem, and told me to look for issues related to the operating conditions. But damn it, it’s a salt solution containing acid – the pump is installed three meters away from its outlet, and it pumps water from underground upward into a pipe gallery. How am I supposed to find problems with the operating conditions in such a situation?