Brief Analysis of the Theory of Magnetic Coupling System of Magnetic Flap Level Gauge

The magnetic flap level gauge is a level detection device that consists of a float with a permanent magnet that floats on the liquid surface. The magnet inside the float is exactly at the liquid surface position. Through magnetic coupling, the external flap is turned over, thereby indicating the liquid level of the medium in the tank. The magnetic flap level gauge realizes the detection of liquid level or interface position based on the magnetic coupling system theory and buoyancy principle. It is a typical application of magnets in level gauges. The magnetic coupling system theory of the magnetic flap level gauge is briefly analyzed as follows:

The magnetic flap level gauge contains a magnetic coupling system consisting of two magnetic fields: the float magnetic system and the magnetic flap magnetic system. The details are as follows:

First, the float magnetic system composed of a float: As a component for sensing liquid level, the float has 6 to 10 cylindrical magnets of varying numbers embedded inside, or two magnets are combined back to back, thus forming a magnetic field on the circumferential surface of the float. The magnetic field radius has good expansibility and a long magnetic action distance, generally required to reach 20 to 30 mm, so that the magnetic force of the float is coupled to the magnetic flip sheet in the display panel.

Second, the magnetic flip-piece magnetic system is composed of magnetic flip pieces: each flip piece has equal size and mass, and a magnetic column is placed inside. The magnetic poles of the magnetic column are self-locking and attracted to each other in the NS law. When there is no external magnetic field, the flip pieces are attracted to each other and connected as a whole.

When the float rises and falls with the liquid level, the magnetic field force of the float causes the flap to flip. Because the magnetic field of the flap is weak and the mass is light, under the action of the float magnetic field, the flap closest to the float directional magnetic field will deflect an angle and be in a horizontal state. The height of this flap is the liquid level.

The magnetic coupling between the float and the magnetic flap must be appropriate, because as long as one of the magnetic properties is too large or too small, the magnetic flap level gauge will not work properly. If the float is strong or the distance is close, the flap will flip 360° and the color of the flap will not change; on the contrary, if the float is weak or the two are far apart, the force of the float on the flap is small and cannot overcome the self-locking suction between the flaps, and the flap will not flip. The magnetic column in the flap must match the magnetic property of the float and its own mass. If the magnetic property of the flap is small or the mass is large, the self-locking suction between the flaps is insufficient and interlocking cannot be achieved. The flaps will flip inconsistently and a "speckled face" phenomenon will occur; if the magnetic property of the flap is too large or the mass is light, the self-locking suction between the flaps is strong, and the magnetic property of the float cannot overcome the self-locking suction between the flaps, resulting in the flap not flipping.