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What should be paid attention to in the application of electromagnetic flow meter?

What should be paid attention to in the application of electromagnetic flow meter?

2021-10-28


In the chemical industry, petroleum, paper-making, metallurgy, textile, environmental protection, food and other industries, the technical difficulty and complexity of flow measurement are relatively high. Research on flow measurement can help improve product quality, reduce operating costsand solve energy conservation and environment protection.


The electromagnetic flow meter has no obstructing flow parts in the measuring tube, no pressure loss, energy saving and consumption reduction, and it is better than other types of flow meters in terms of reliability and stability, but there are still some key points that need to be paid attention to in practical applications.

 

The installation position of the transmitter should be chosen where the measuring tube can be filled with liquid at any time to avoid the situation where there is no liquid and the pointer is not at the zero point. It is recommended to install it vertically to reduce errors caused by bubbles caused by liquid flowing through the electrode. If you need to install it horizontally, make sure that the two electrodes are on the same level.


When installing the electromagnetic flow meter, if the fluid is in a pipeline with anode protection, it is recommended to use a ground ring for good grounding; if the sensor is connected to the pipeline, an insulating pad should be installed between the flanges and an insulating sleeve for the screw .

 

If it is installed on a grounded metal pipe, the system potential balance is achieved through the grounding terminal on the electromagnetic flow meter transmitter, that is, it is connected to the grounding terminal through a copper core wire with a cross-sectional area of not less than 6mm2; when it is installed on an underground metal On the pipeline, both flanges are connected to the pipeline flange by a copper core wire with a cross-sectional area of at least 6mm2 and grounded; connect the transmitter or sensor junction box to the ground terminal to achieve system potential balance; when the electromagnetic flow The meter is installed on a plastic pipe or a pipe with an insulating lining, and the system potential balance is achieved through an additional grounding ring, which is connected to the grounding terminal through a copper core wire with a cross-sectional area of at least 6mm2.


The electromagnetic flow transmitter should be installed in a dry and ventilated place indoors to avoid excessively high ambient temperature, equipment with a strong magnetic field around it, and corrosive gas.

 

In order to ensure that the measuring tube of the electromagnetic flow transmitter is filled with the measured medium, it is recommended to install it vertically, with the flow from bottom to top, especially for liquid-solid two-phase flow, which must be installed vertically. If the site only allows horizontal installation, you must ensure that the two electrodes are on the same horizontal plane.

 

Both ends of the electromagnetic flow transmitter should be equipped with valves and bypasses.

 

The casing of the electromagnetic flow change transmitter and the metal pipe should be well grounded. The casing of the converter should also be grounded. The grounding resistance should not be greater than 10 ohms and cannot be shared with the grounding wires of other electrical equipment. If it is not possible to ensure that the transmitter housing is in good contact with the metal pipe, use a metal wire to connect and ground.

 

In order to avoid interfering signals, the signal between the transmitter and the converter must be transmitted by shielded wires. It is not allowed to put the signal cable and the power cable in the same cable pipe in parallel. The length of the signal cable should generally not exceed 30m.

 

Because the electromagnetic flow meter measures a weak electric potential, all external interference needs to be eliminated, so good grounding is a necessary condition to ensure the stable operation of the electromagnetic flow meter. Usually grounding is achieved through the grounding connection between the grounding ring or the reference electrode in the sensor and the piping system.

 


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