How reed sensing works
A magnet moves near the reed switch, causing the sealed contacts to close or open. In liquid level sensors, the magnet is often inside a float.
Technical Library: Reed Sensors
Reed Sensor Guide for Level, Proximity and Flow Detection
Reed sensors use a magnet and hermetically sealed reed switch to detect position, liquid level, proximity or flow with low power consumption and simple interface circuits.
Liquid levelMagnetic proximityFlow detectionAutomotive / HVAC / industrial
What this component is used for
Low-power operation
A simple reed switch draws no steady-state power until the circuit is actuated, useful for battery-powered or low-energy controls.
Configurable mechanics
Vertical, horizontal, stainless-steel and plastic configurations can be selected based on fluid, temperature, pressure and mounting constraints.
Application details
Liquid level monitoring
Detect full, empty or multi-point tank levels in coolant, fuel, water, HVAC and industrial fluid systems.
Position and proximity sensing
Detect doors, covers, cylinders, floats or moving machine elements with a sealed magnetic switch.
Flow and appliance sensing
Use magnet-equipped moving elements to trigger reed switches in pumps, white goods and process equipment.
Automotive and industrial controls
Provide simple, robust switching signals where electronics need environmental separation.
Selection factors engineers should confirm
- Fluid compatibility, temperature, pressure and housing material.
- Mounting orientation and float travel.
- Switching voltage/current and protection against inductive loads.
- Magnet strength, actuation distance and hysteresis.
- Connector, cable, sealing and IP/environmental requirements.
Engineering note: Reed sensors are simple but mechanical integration matters. Incorrect float material, mounting direction or magnet distance can cause more issues than the electrical interface.
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