A basic magnetic level sensor is a type of level measurement device used to determine the liquid level in a container, such as a tank. It operates based on the principle of magnetic coupling between a float and a sensor located outside the tank. The sensor is typically mounted on the tank's exterior, and the float is inside the tank, buoyed up by the liquid being measured.
Here's a step-by-step description of how a basic magnetic level sensor works:
Construction: The sensor consists of a housing with a reed switch or Hall effect sensor mounted inside. These sensors are sensitive to changes in the surrounding magnetic field.
Float: The float is a buoyant object that is designed to move vertically within the tank, following the liquid level changes. It is often a hollow, sealed container made of a non-magnetic material, with a magnet embedded inside.
Magnetic Interaction: As the liquid level in the tank changes, the float rises or falls accordingly. When the float moves, the magnet inside the float changes its position concerning the sensor outside the tank.
Reed Switch or Hall Effect Sensor: The sensor inside the housing is designed to detect the magnetic field changes caused by the moving magnet inside the float. Depending on the technology used (reed switch or Hall effect), the sensor will respond differently.
Reed Switch: When the magnetic field around the reed switch changes, it either opens or closes an electrical contact. If the float's magnet moves close enough to the reed switch, it will cause the contacts to close or open, indicating the liquid level at that specific position.
Hall Effect Sensor: The Hall effect sensor generates a voltage that changes proportionally with the strength of the magnetic field it detects. As the float's magnet approaches or moves away from the sensor, the Hall effect sensor's output voltage will vary accordingly, providing a level indication.
Output Signal: The sensor's electrical output is then processed, often by an external controller or display unit, which converts the signal into a readable level value. This value can be displayed on a local display, transmitted to a control system, or used for various monitoring and control purposes.
By continuously monitoring the magnetic interaction between the float and the sensor, the level sensor accurately tracks the liquid level inside the tank and provides real-time level measurements. It is a simple and reliable method for level detection and is widely used in industrial, commercial, and domestic applications.