how to avoid these "pits" during the use of electromagnetic flowmeters
Author: PhilemonTime: 2020-11-25
When the electromagnetic flowmeter is in use, there will sometimes be measurement errors. What is the problem? What is the reason? Today, the flowmeter manufacturer Qingtian Instrument will teach you a few points.
1. The liquid in the tube is not full. Due to insufficient back pressure or poor installation position of the flow sensor, the liquid in the test tube cannot be filled. When there is a small amount of gas in the tube, the measurement result will deviate from the actual value, causing small errors; when there are many gases, the measured value will be unstable and the output will shake. At this time, the measured value has a large error and cannot be used as Correct result.
2. The tested liquid contains solid components. When this happens, the meter usually has the following problems: slurry noise, dirt on the surface of the motor, the lining is worn or covered by deposits, the flow cross-sectional area is reduced, the conductive deposit layer or the insulating deposit web electrode or lining, if There are conductive materials in the deposited layer, and the flow signal is likely to be short-circuited, causing the meter to malfunction.
3. Improper selection of electrode and grounding ring materials. Electromagnetic flowmeter and the medium contacting parts that cause failure due to material mismatch with the measured medium are electrodes and grounding rings. Improper matching is mainly due to the surface effect of electrodes, in addition to corrosion resistance. Whether the electrode can reliably detect the flow signal is very important to the performance of the flowmeter. The grounding ring acts as an electrical connection with the medium, and is connected to the zero potential through the grounding wire. When the process pipeline connected to the sensor is plastic or has an insulating coating inside, a grounding ring must be installed, otherwise the instrument will not work normally.
4. Uneven conductivity
In the proportioning process, "dosing" liquid is often injected into the liquid, and the injection liquid is often added by a reciprocating pump. If the conductivity of the injected liquid and the main liquid are different, and the mixed liquid is not evenly mixed, if the electromagnetic flowmeter sensor is installed downstream, the output of the meter will be shaken due to the sharp change in the conductivity, although the liquid conductivity is greater than the threshold and the slow change will not be Affect the normal measurement of the electromagnetic flowmeter. This phenomenon often occurs in the process of adding coagulant to raw water in water treatment engineering.
If you encounter other problems during the use of the electromagnetic flowmeter, you can also contact us online or call at any time.