A basic magnetic level sensor is a device used to determine the level of a liquid inside a container, such as a tank or a reservoir, using the principles of magnetism. It typically consists of a few key components:
Float: The float is a buoyant object that can move up and down within the liquid. It is usually cylindrical in shape and contains a built-in magnet. The float's position within the liquid changes as the liquid level rises or falls.
Guide Tube or Housing: This is a cylindrical tube or housing that encases the float and provides a channel for its movement. The guide tube is installed vertically within the container, allowing the float to move freely along its length.
Reed Switches or Hall Effect Sensors: These are the sensors used to detect the position of the magnet within the float. Reed switches are magnetic switches that respond to the presence of a magnetic field, while Hall effect sensors are solid-state devices that produce an output voltage proportional to the strength of the magnetic field. These sensors are typically mounted at specific levels within the guide tube.
Here's how the basic magnetic level sensor operates:
Empty State: When the container is empty or the liquid level is below the float, the float rests at the bottom of the guide tube, and the sensors are in their deactivated state. This position corresponds to the lowest level.
Rising Liquid Level: As the liquid level within the container rises, it also lifts the float along with it due to buoyancy. As the float moves upward, the magnet inside it approaches the reed switches or Hall effect sensors positioned at various levels within the guide tube.
Sensor Activation: When the magnet on the float comes close to a reed switch or a Hall effect sensor, it triggers the sensor to activate. This activation results in a change of the sensor's state, typically from open to closed (in the case of reed switches) or from low to high (in the case of Hall effect sensors).
Output Signal: The change in sensor state is used to indicate that the liquid level has reached a certain point within the container. This information can be processed by a control system or a monitoring device to provide a reading or trigger an action, such as sounding an alarm, stopping a pump, or activating a valve.
Full State: As the liquid level continues to rise, the float reaches its highest position within the guide tube. At this point, all relevant sensors are activated, indicating that the container is full.
Falling Liquid Level: When the liquid level decreases, the float descends along with it. As the magnet on the float moves away from the sensors, they deactivate, and their states return to their initial positions.
Magnetic level sensors are simple and reliable devices that find applications in various industries, such as manufacturing, chemical processing, oil and gas, and water management, to monitor and control liquid levels in tanks and other containers.