Precautions for using flowmeters to measure corrosive media

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　　The media measured by flowmeters are extremely diverse, including corrosive media as well. When selecting a flow meter for corrosive media, it is essential to take into account corrosion prevention and resistance. The editor would like to share some insights on the issue of measuring flow rates with corrosive media in flow meters. 　　Corrosion is the phenomenon in which metals are damaged due to chemical reactions in their environment. All metals and alloys can be corrosion-resistant in certain specific environments, but they are highly susceptible to corrosion in other environments. Generally speaking, there are no industrial metal materials that are corrosion-resistant in all environments. 　　Corrosive media cause severe damage to flow measurement instruments: (1) Corrosive media corrode the key components of the flow measurement instrument that are in direct contact with the medium, resulting in damage and loss of functionality. For example, corrosion can damage the diaphragm of the differential pressure transmitter, causing the silicone oil to leak out and resulting in complete failure of the device. Corrosion of the electrodes in electromagnetic flowmeters can cause leakage of the medium, leading to damage such as the burnout of the excitation coil. 　　(2) The key components of flow measurement instruments are subjected to corrosion by corrosive media over time, causing changes in their geometric dimensions and thereby reducing the accuracy of the instruments. For example, in a rotameter, when the rotor is corroded by the fluid, its dimensions decrease, resulting in a lower flow measurement value. Similarly, in vortex flow meters, the vortex generator is corroded by the fluid, causing its width to decrease and the surface facing the flow to become rough, which in turn leads to changes in the flow coefficient. 　　(3) Shorten the lifespan of the instrument. For example, components such as the conical tube in metal tube rotameters can develop through holes at their welds after several years of use. 　　(4) Leaks of corrosive substances, if not detected and addressed in a timely manner, can easily lead to safety and personal accidents. 　　Measures against fluid corrosion in flow measurement: (1) Regularly replace the instruments. The ways in which corrosive media affect metals are varied. Some types of corrosion occur at a rapid pace, that is, general corrosion, while other types are mild and proceed slowly, that is, local corrosion. When selecting instruments, a specific analysis of the particular circumstances should be conducted before making a decision. 　　(2) Avoid the heavy and focus on the light. Avoiding the more problematic areas means, based on a thorough understanding of the process flow and the properties of the relevant media, selecting an appropriate measurement approach. This can also achieve the goals of measurement or control over the production process by avoiding highly corrosive areas and opting for those with lower corrosion levels; in some cases, the type of parameter being monitored may even be changed. 　　Flow metering is one of the components of measurement science and technology, and it is closely related to the national economy, national defense construction, and scientific research. Doing this work well plays an important role in ensuring product quality, improving production efficiency, and promoting the development of science and technology. Especially in today’s era of energy crises and increasing automation in industrial production, the significance and role of flow meters in the national economy have become even more evident.