There are many types of media measured by the flowmeter, including ordinary and corrosive. For corrosive media, the selection of the flowmeter must be treated with corrosion resistance.1 Corrosion phenomenonCorrosion is a phenomenon in which metals suffer damage due to chemical action in their environment. All metals and alloys can be resistant to corrosion in some specific environments, but they are very sensitive to corrosion in other environments. Generally speaking, industrial metal materials that are resistant to corrosion in all environments do not exist.2 the damage of corrosive medium to the flow measuring instrumentThe corrosiveness of the medium is a serious threat to the flow measuring instrument: a. The corrosive medium will corrode the key parts of the flow measuring instrument in direct contact with the medium, causing damage and loss of function. For example, corrosion causes damage to the diaphragm of the differential pressure transmitter, and complete failure due to leakage of silicone oil. Electromagnetic flowmeter electrodes are corroded and the medium leaks out, causing the excitation coil to burn out. B. The key parts of the flow measuring instrument are corroded by corrosive medium for a long time, which changes the geometrical size, which causes the accuracy of the instrument to decrease. For example, after the rotor in a rotameter is corroded by the fluid, the outer dimension is reduced, resulting in a low flow rate indication. Another example is that the vortex generator in the vortex flowmeter is corroded by the fluid and the width is reduced, and the surface of the front flow surface becomes rough, which causes the flow coefficient to change. C. Shorten the life of the instrument. For example, the conical tube and other parts in the metal tube rotameter, after a few years of use, the welding part was broken. D. Leakage of corrosive media, if not discovered in time and treated in time, can easily lead to safety and personal accidents.3 Measures for fluid corrosion in flow measurementa. The corrosive medium of the instrument is regularly replaced, and there are various conditions for the corrosion of metals. Some of the corrosion rate is very fast, that is, general corrosion, and some corrosion is slight, and the rate is very slow, that is, local corrosion. When making instrument selection, specific analysis should be made according to the specific situation, and then a decision should be made. B, avoid the heavy and light. Avoiding the heavier and lighter is to choose the measurement plan reasonably based on the in-depth understanding of the technological process and the characteristics of the relevant media, which can also achieve the purpose of measuring or controlling the production process, avoiding the corrosive parts, and choosing the less corrosive Even change the type of parameter to be adjusted.
Post time: 21-09-21