A basic magnetic level sensor, also known as a float switch or magnetic float sensor, is a simple device used to monitor liquid levels in various applications, such as tanks, reservoirs, and industrial processes. It relies on the principle of magnetic attraction to determine whether a liquid level has reached a certain point.
Here's how a basic magnetic level sensor operates:
Components: The sensor consists of two main components: a float and a stationary housing. The float is usually a buoyant object made of a non-corrosive material, such as plastic or stainless steel. The housing contains a reed switch, which is a small electrical switch that responds to the presence of a magnetic field.
Mounting: The sensor is installed vertically within the liquid container or tank. The float is connected to the housing through a stem or cable. As the liquid level changes, the float moves up and down along the stem.
Magnetism: A small permanent magnet is embedded within the float or attached to it. This magnet generates a magnetic field around itself.
Reed Switch: Inside the stationary housing, near the expected liquid level, there is a reed switch. A reed switch is a pair of metal reeds (thin, flexible metal contacts) encased in a sealed glass tube filled with an inert gas. When no magnetic field is present, the reeds remain in their default position, maintaining an open circuit.
Changing Levels: As the liquid level rises or falls, the float follows suit due to its buoyancy. When the float reaches a certain level, the magnet on the float comes close enough to the reed switch inside the housing. The magnetic field from the magnet causes the reeds in the reed switch to attract each other, closing the electrical circuit.
Electrical Signal: When the reed switch closes, it completes an electrical circuit, allowing current to flow. This closure triggers a signal that can be used to indicate the liquid level status. The signal can be used to activate alarms, control pumps, or send information to monitoring systems.
Level Detection: The point at which the reed switch activates depends on the position of the float and the specific design of the sensor. Generally, the sensor can be configured for high-level detection (when the liquid level reaches a specific upper point) or low-level detection (when the liquid level drops to a specific lower point).
Advantages and Limitations: Magnetic level sensors are simple, cost-effective, and reliable for basic level monitoring. However, they may not be suitable for extremely corrosive liquids or high-temperature environments. Additionally, the design of the float and housing should be chosen carefully to prevent interference from turbulent liquid flow.
In summary, a basic magnetic level sensor works by using the interaction between a float with a built-in magnet and a reed switch within a stationary housing. Changes in liquid level cause the magnet and reed switch to come into proximity, closing an electrical circuit and indicating the level status.