The electromagnetic flowmeter has the advantages of no resistance and no pressure, which fully reduces the resistance in the pipeline and meets the requirements of energy saving and consumption reduction.
In petrochemical, chemical, electric power, metallurgy, municipal administration, pharmaceutical and other industries, the technical difficulty and complexity of flow measurement is quite high. Studying them plays an important role in improving product quality, reducing business operating costs, saving energy and solving environmental protection issues.
The electromagnetic flowmeter has the advantages of no resistance and no pressure, which fully reduces the resistance in the pipeline and meets the requirements of energy saving and consumption reduction. Therefore, it has been widely valued by the industry. However, electromagnetic flowmeters have the above advantages and are much better than most other types of flowmeters in terms of reliability and stability, but some problems may occur during actual use. The following editor lists the key points that should be paid attention to in engineering applications of electromagnetic flowmeters.
1. The transmitter should be installed in a position where the measuring tube can be filled with liquid at any time to prevent the illusion that there is no liquid in the measuring tube and the pointer is non-zero. Vertical installation is recommended to reduce errors caused by bubbles in the liquid passing through the electrodes. When placed horizontally, both electrodes must be kept at the same level to prevent sedimentation or air insulation at the top of the pipe.
2. If necessary, the pipeline can be vented, and the built-in empty pipe detection circuit stops accumulation and flow signal output.
3. If the electromagnetic flowmeter is installed on a grounded metal pipe, balance the system potential through the ground terminal of the electromagnetic flowmeter transmitter. That is to say, connect to the ground terminal through a copper core wire with a cross-sectional area greater than 6mm2. If the electromagnetic flowmeter is installed on an ungrounded metal pipe, the two flanges shall be connected to the pipe flange and grounded by a copper core conductor with a cross-sectional area of at least 6mm2. Connect the transmitter or sensor junction box to the ground terminal to maintain system potential balance. If the electromagnetic flowmeter is installed on a plastic pipe or a pipe with an insulating lining, the system potential balance is achieved through an additional grounding ring, which is connected to the grounding terminal through a copper core conductor with a cross-sectional area of at least 6mm2.
4. The transmitter should be installed in a dry and ventilated place indoors. It should not be placed in a place where the ambient temperature is too high or subject to strong vibration. Equipment with strong magnetic fields, such as large motors and transformers, should be avoided as much as possible.
5. In order to fill the measuring tube of the electromagnetic flow transmitter with the test medium, it is recommended to install it vertically. Especially for liquid-solid two-phase flow, it must be installed vertically. If the site only allows horizontal installation, ensure that both electrodes are at the same level.
6. The AC potential of several millivolts measured by the electrode of the electromagnetic flow transmitter is based on the potential of the liquid in the transmitter. In order to stabilize the liquid potential and ensure stable measurement, both ends of the transmitter housing and the metal tube must be well grounded. The converter housing must also be grounded. The grounding resistance cannot be greater than 10 ohms and cannot be shared with the grounding wires of other electrical equipment.
Hangzhou Economic Development Area，Hangzhou 310018，China
