Working Principles： 

◦ Magnetic Float Type：This is a commonly used type. It consists of a float with a built - in permanent magnet, a guide rod, and a magnetic flip - plate assembly. The float moves up and down along the guide rod with the change of the liquid level. The magnetic field of the float triggers the magnetic elements in the flip - plates outside the guide rod to rotate, changing the color of the flip - plates (such as from white to red), so as to visually display the liquid level height.

◦ Glass Tube Type：Based on the principle of communicating vessels, a glass tube is connected to the side of the tank. The liquid in the tank enters the glass tube, and the liquid level in the glass tube is the same as that in the tank, so that the liquid level can be observed directly through the glass tube.

Structural Features：

It usually includes components such as a measuring body, a display device, and a connection flange. The measuring body is made of materials such as stainless steel (SS304, SS316) or carbon steel to adapt to the marine environment. The display device can be a sight glass or a magnetic flip - plate, etc. • 

Technical Parameters：

The pressure - bearing capacity is generally up to 4.0 MPa, and the temperature range is usually - 40 °C to 150 °C, and there are also high - temperature versions that can reach 450 °C.

Installation and Maintenance：

During installation, it is usually installed on the side of the tank through a flange or threaded connection. Attention should be paid to proper sealing and alignment to prevent leakage. During maintenance, regular inspection and cleaning of the sight glass or indicator mechanism are required, and periodic calibration may also be required.