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The repair of magnetic flap gauge failures must be carried out on the basis of a thorough understanding of the working principle of these gauges. This post shares experience in detecting and addressing faults in magnetic flap gauge systems, using actual repair examples as references. Examples of magnetic flap level gauge maintenance: yunrun.com.cn/tech/2095.html. Working principle and structure of magnetic flap level gauges. The structure of a magnetic flap level gauge is shown in Figure 1. The installation methods for such level gauges include side mounting, top mounting, and suspension mounting. Since there are also columnar types of magnetic flip plates, some products are referred to as magnetic flip-column level gauges; the working principle of both is the same. Changhui Instruments commonly refers to them as magnetic flip plate level gauges. It operates based on the principle of buoyancy and magnetic coupling. As the liquid level in the container under test rises or falls, the magnetic float in the measuring tube of the level gauge moves up or down accordingly. The permanent magnet inside the float transmits a magnetic signal to the magnetic flip indicator, which causes the red and white flaps to rotate 180°. When the liquid level rises, the flaps change from white to red; when the liquid level drops, they change from red to white. The point where the red and white flaps meet on the magnetic flip indicator indicates the actual height of the liquid level. http://yunrun.com.cn/upload/201807/21/201807211355043658.png Figure 1: Schematic diagram of the structure of a magnetic flap level gauge. Examples of maintenance for magnetic flap level gauges. In top-mounted level gauges, red is indicated only at the gas-liquid interface, while the area below the liquid level is shown in white. Go to the site and use a magnet to brush the outside; the flap flips normally ； Disassembly inspection revealed that the float and connecting rod had come loose. After reconnecting and installing the linkage with the float, the liquid level indication is normal. In a top-mounted flap level gauge, the magnet is not located inside the float; the float is connected only to a linkage, which in turn is connected to the magnet found in the upper measurement tube. As the liquid level changes, the float moves the linkage, causing the magnet to move up and down within the measurement tube, which in turn causes the red and white magnetic plates in the indicating section to flip. At the moment the float separates from the rod, the rod drops rapidly due to its own weight; before the magnetic flap has time to change from red to white, the magnet has already moved away from the flap, causing it to return to its white color. This is why everything below the liquid level appears white. The indication of the top-mounted level gauge differs significantly from the actual liquid level, and its changes are slow. By moving a magnet up and down on the plexiglass cover of the level gauge, the flap moves properly; it is suspected that there is a problem with the float. Inspections and repairs are carried out after shutdown in connection with the process. Inspection revealed that the float and the linkage were covered with a lot of dirt; after cleaning, the instrument returned to normal. During the inspection, the level gauge body was lifted vertically by 50 cm. Under normal conditions, the indication of the magnetic flip switch should have decreased by 50 cm, but there was virtually no change in the indication. Upon further inspection, it was found that dirt had accumulated on the linkage and the float, causing the float to move slowly or even not move at all. After cleaning the measurement catheter and float, the display returned to normal. Issues such as inaccurate readings on magnetic flap level gauges, level fluctuations, and straight-line trends on DCS curves are often caused by a dirty float, as well as by the viscosity and crystallization of the medium being measured ； It must be parked before it can be disassembled for inspection, cleaning, or treatment. The remote display of the magnetic flap level gauge is abnormal, showing jumps or straight lines on the paperless recorder. Using a magnet to swipe up and down on the flap level gauge, the flaps can switch normally, but the display does not respond sensitively; this issue persists even after draining waste fluid. It was determined that the problem lay with the float; upon disassembly and inspection, it was found that there was a lot of black dirt attached to the inner wall of the measurement tube as well as the float itself. http://yunrun.com.cn/upload/201807/21/201807211407074454.png