SB20

Float, Level Sensors

Float and level sensors measure the position of a liquid and are most often used in industrial applications. Float sensors work by placing a buoyant object or magnetic field detector on top of the liquid in a container. As the liquid level fluctuates, the float either rises or falls, depending on the direction of the liquid. This triggers a signal that is sent to alert operators that the liquid level has changed, often via a controller or display unit.

Application Field

Float and level sensors are mostly used to monitor and control the level of liquids in tanks, stacks, reservoirs, septic tanks, and more. Float sensors are used to detect levels of water in water tanks, fuel levels in fuel tanks, and chemical levels in various storage containers. Their versatile applications can be seen across many industries such as aerospace, petrochemical, and general engineering.

The versatility of float and level sensors makes them one of the most widely used sensing devices in many systems. They can be used to detect levels in a wide variety of liquids in both low and high accuracies. In many industries, float and level sensors are also used to detect levels in other hazardous or corrosive materials, giving operators the ability to monitor liquid levels while minimizing hazardous exposure.

Working Principle

Float and level sensors work by using magnetic, buoyant, or resistive principles to detect the level of liquid in a container. Generally, a float is placed in the liquid and is attached to a stem which is connected to a magnetic field detector. As the level of the liquid increases, the float rises, and the magnetic field detector sends a signal to the controller or display unit.

The magnetic float switch operates using the principle of Magnetic reed switches. A reed switch is simply a type of switch which is activated when a magnetic field is present. The float is connected to a plunger which is then moved by the rising liquid level. As the water level nears the top of the tank, the plunger contacts the switch’s poles and closes the circuit, triggering the signal.

Buoyancy float level sensors are the most common type of float switch. These sensors work by suspending a mass (a float) in the liquid. As the liquid level rises, the density of the float decreases, causing it to rise. At the same time, the float is connected to a stem that is connected to an electrical contact, which is then connected to a controller or display unit. As the liquid level increases, the float rises and activates the contact, triggering the signal.

Resistive level sensors are also used in certain applications. In this setup, the a resistive element is placed in a container with the liquid. As the liquid level increases, the resistive element changes its resistance and sends a signal to the controller. This type of sensor is most often used in applications where the liquids are relatively corrosive or volatile.