Electromagnetic flowmeter in the use of precautions and installation requirements

　　Precautions in the use of electromagnetic flow:

　　1. Since the induction signal voltage of the electromagnetic flowmeter is very small, it is easily affected by noise. The reference potential must be the same as that of the measured liquid. Whether the electromagnetic flowmeter is grounded correctly is directly related to the accuracy and stability of the measurement.

　　(1) When the flow meter casing is grounded, the measured liquid is electrically connected to the earth and is at zero potential, thus inducing symmetrical potential signals of equal magnitude but opposite polarity on the two electrodes of the sensor; at the same time, the flow meter casing is grounded, which can play a shielding effect to suppress electromagnetic interference from the outside world and the excitation system.

　　(2) When there is a strong stray current in the pipeline, the stray current should be blocked from flowing through the flowmeter. When installing, first install an insulating short tube between the pipeline and the flowmeter, and then connect the two ends of the pipeline with a copper wire with an area of ​​not less than 16mm2. In this way, the current in the pipeline is diverted from the copper wire and no longer passes through the flowmeter, thereby reducing interference.

　　2. Selection of installation location for electromagnetic flowmeter

　　(1) When there are elbows, valves, and pumps upstream and downstream of the electromagnetic flowmeter installation location, the fluid forms a lateral secondary flow in the pipeline, the velocity distribution deviates, and the measurement accuracy decreases when the straight pipe section is insufficient. Generally, the length of the upstream straight pipe section is not less than 10D, and the length of the downstream straight pipe section is not less than 5D. When there are pumps and other equipment upstream, the straight pipe section length is required to be not less than 30D. Do not install the meter on the inlet side of the pump, as this will cause a vacuum in the pipeline and cause measurement errors. Where D is the inner diameter of the pipeline.

　　(2) When measuring, ensure that the pipe is filled with liquid, otherwise it will affect the measurement accuracy. When installing the instrument in an inclined or vertical position, the measured liquid should flow from bottom to top. The measured liquid should not contain too many bubbles.

　　(3) Avoid strong vibration of the pipeline as much as possible. If it cannot be avoided, the sensor and transmitter should be installed separately, and the pipeline should be fixed within 2 to 5D on the upstream and downstream sides of the flow meter to avoid damage to the transmitter due to strong vibration.

　　(4) There should not be any large motors or other equipment near the flow meter, otherwise it will cause inductive interference and affect the measurement accuracy of the instrument.

　　(5) It is forbidden to inject chemicals on the upstream side of the flow meter, as this will easily cause uneven distribution of conductivity, thus causing serious interference to the measurement of the flow meter.

　　(6) When installing the electromagnetic flowmeter, the axis of the electrode should be approximately horizontal when installed horizontally. If the axis of the electrode is perpendicular to the ground, bubbles are likely to gather near the upper electrode, blocking the liquid from contacting it, while the lower electrode is likely to be covered with dirt.

　　Supmea has been producing electromagnetic flowmeters for many years. If you encounter any problems in the selection, installation, use and maintenance of electromagnetic flowmeters, you can contact Supmea staff at any time and we will answer you as soon as possible.