Electromagnetic flow meter is a common flow measuring instrument that can measure the flow of liquid media. It has the advantages of high measurement accuracy and good stability, and is widely used in many industries. However, electromagnetic flow meter also have certain limitations, and some issues need to be paid attention to in practical applications.

1. Limitations of measurement media

Electromagnetic flow meter can only measure the flow of conductive liquids, but cannot measure the flow of non-conductive media, such as gas, heated water with better water treatment, etc. Therefore, when measuring the medium, you need to pay attention to its conductivity. If the medium is not conductive, you need to choose other types of flow measurement instruments. In addition, under high temperature conditions, the lining of the electromagnetic flow meter also needs to be considered to avoid corrosion and damage by the medium.

2. The relationship between measurement accuracy and density

According to the measurement requirements, for liquid media, the mass flow rate should be measured, and the electromagnetic flow meter determines the volume flow rate under working conditions by measuring the speed of the conductive liquid. Therefore, when using an electromagnetic flow meter for flow measurement, it is necessary to consider the change in fluid density. Different fluids have different densities, and they change with changes in temperature. If the electromagnetic flow meter converter does not consider the fluid density and only gives the volume flow rate at normal temperature, it is easy to cause measurement errors.

3. Complexity of installation and debugging

The installation and debugging of electromagnetic flow meter are more complicated than other flow meter. The transmitter and converter must be used together, and two different types of instruments cannot be used together. When installing the transmitter, it must be strictly in accordance with the product instructions and must not be affected by vibration, strong magnetic field, etc. Before use, the gas remaining in the measuring tube must be exhausted, otherwise it will cause large measurement errors. At the same time, the transmitter and the pipeline must have good contact and good grounding during installation to avoid the impact of the external environment on the measurement.

4. The influence of dirt on measurement

When measuring viscous liquids, sticky matter or sediment adheres to the inner wall of the measuring tube or the electrode, which may cause measurement errors. If the dirt on the electrode reaches a certain thickness, the meter may not be able to measure. Therefore, in practical applications, the measuring tube and electrode need to be cleaned regularly to ensure the normal operation of the electromagnetic flow meter. In addition, some media may precipitate or accumulate in the flow meter pipe, which will also affect the measurement results.

For this situation, electromagnetic flow meter generally use a variety of antifouling technologies, such as angle installation, tilt installation, exhaust pipes, self-cleaning electrodes, etc. Among them, oblique installation and inclined installation can form a rotating flow when the liquid passes through the pipe, reducing the impact of sediment or dirt on the electrode. The exhaust pipe can discharge air and gas from the pipe to avoid affecting the measurement results. Self-cleaning electrodes remove attached dirt through vibration or rotation of the electrode surface to ensure measurement accuracy.

In addition, the measurement accuracy of the electromagnetic flow meter is also affected by the flow state in the pipeline. When there are irregular flow states such as eddies and vortices in the pipeline, measurement errors will occur. Therefore, when installing an electromagnetic flow meter, it is necessary to choose a suitable installation location and method to ensure regular liquid flow and avoid the occurrence of eddies and whirlpools.

To sum up, when electromagnetic flow meter measure viscous liquids and liquids containing solid particles, they are easily affected by dirt and the flow state in the pipeline, which may cause measurement errors. In order to ensure measurement accuracy and reliability, the measuring tube and electrode need to be cleaned regularly, and corresponding anti-fouling technology and installation measures must be taken.