Questions about electromagnetic flowmeters
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A company has two electromagnetic flowmeters; one of them is used to measure sewage, with a measurement range of 0–300 m3/h； An electromagnetic flowmeter is used to measure domestic water, with a measurement range of 0–20 m3/h. On October 15, 2016, the water in the pipes of the two electromagnetic flowmeters was drained, the valves at both ends were closed, and blind flanges were installed. Question: 1. The flow meter used to measure wastewater showed an accumulated error of 2 cubic meters from October 15, 2016, to March 6, 2017. However, starting from March 6, the meter indicated fluctuations of twenty to thirty cubic meters per hour between 2 a.m. and 6 a.m. every day. Checks on the wiring and grounding showed that everything was normal, and the valves before and after the meter were still closed, so no wastewater was flowing. 2. The flow meter used to measure the volume of water for domestic use showed an accumulated error of 7 cubic meters over a period of five months, from October 15, 2016, to March 15, 2017. On the afternoon of March 15, the blind flange was removed and water for domestic use began to be utilized. The amount of water used at this time was very small, intended only for daily toilet flushing and cleaning purposes. Yet the flow meter indicated a high flow rate; even when the faucets were not turned on, the meter sometimes showed a reading of around 0.1 m3/h. The readings on the meter occurred mostly during the day. Over 10 days, the meter indicated an accumulated water usage of 29 m3, while the actual amount used was estimated to be less than 10 m3. The error over these 10 days was much greater than that during the periods when the meter was not in use. No leaks were found in the pipelines, and the wiring of the meter as well as its grounding were all in order. The instrument parameters have been checked and are all normal. Those with experience, please help analyze from various aspects the reasons behind the sudden increase in the indication errors of these two flowmeters, so that we can identify the real cause! ! !
When the flowmeter is evacuated, its measurements are uncertain. Zero flow should be the condition where no flow occurs when the pipeline is filled with the medium.
This has been done, so it can be ruled out now.
Yes, there is an error, but the error for the first 5 months is very small and acceptable; it suddenly changed later on, and I want to figure out what factors might be causing this.
Yes, there is an error, but the error for the first 5 months is very small and acceptable; it suddenly changed later on, and I want to figure out what factors might be causing this.
It is recommended to check the seal of the downstream valve again
1. If there is an air traffic control detection function, enable it； 2. It is recommended to clean the electrodes ； 3. Appropriately adjust the low-flow cutoff value ； 4. I’m not clear – are blind plates installed at both ends of the flow meter? In other words, it is necessary to confirm that no water has leaked into the pipeline. . 5. Verify the quality of grounding and whether there are any related interferences. .