A basic magnetic level sensor, also known as a magnetic float level sensor, is a simple and reliable device used to measure the liquid level in a container or tank. It utilizes the principles of buoyancy and magnetic coupling to determine the liquid level. Here's how it works:
Components: The sensor consists of two main components: a float and a stationary stem. The float is a hollow, buoyant object usually made of a non-magnetic material like plastic or stainless steel. Inside the float, there is a small magnet. The stationary stem is typically a vertical tube or rod made of a non-magnetic material, such as PVC or stainless steel. The stem houses the sensor electronics.
Mounting: The stem is installed vertically inside the container or tank whose liquid level needs to be measured. The float is allowed to move freely along the stem.
Principle of Operation: The basic principle behind the magnetic level sensor is that the float rises and falls with the liquid level in the tank due to buoyancy. The magnet inside the float moves along with it.
Sensor Electronics: The stationary stem houses a reed switch or a Hall-effect sensor. A reed switch is a magnetically operated switch that closes or opens an electrical circuit when exposed to a magnetic field. A Hall-effect sensor, on the other hand, detects changes in the magnetic field strength.
Detection: As the float moves up or down with the liquid level, the magnet inside the float comes in close proximity to the reed switch or Hall-effect sensor located in the stem. When the magnetic field from the float's magnet interacts with the sensor, it triggers the switch to either open or close the circuit, depending on the type of sensor used.
Output: The change in the switch's state produces an electrical signal that indicates the liquid level. This signal can be transmitted to a control panel, indicator, or other instrumentation for further processing and display. For instance, the sensor could activate an alarm when the liquid level reaches a certain threshold or trigger a pump to start or stop filling the tank.
Accuracy and Limitations: Magnetic level sensors are generally reliable, cost-effective, and suitable for various liquids, including corrosive and hazardous substances. However, they might have some limitations, such as limited accuracy and sensitivity in very large or shallow tanks. Additionally, factors like external magnetic fields or build-up of debris on the float can affect the sensor's performance.
In summary, a basic magnetic level sensor utilizes the movement of a magnetic float along a stationary stem to detect the liquid level in a container. Its simplicity and reliability make it a popular choice for level measurement in many industrial and commercial applications.