Liquid level sensors have been around for decades, in markets such as food and beverage, industrial, medical and domestic printing, agriculture, automotive and white goods for leak detection or level measurement. Level switches are used to detect liquid or powder levels, or interfaces between liquids. These level measurements are indicated via an electrical switching action. Level switches can be used either as an alarm device or as control switches, turning something on or off, such as a pump, or sending a signal to a valve actuator. What makes level switches special is that they have a switched output and can be either electromechanical or solid-state, either normally open or normally closed.
Float Type –
Float type level switches are one of the most cost-effective but also well-proven technologies for liquid level sensing. A float switch includes a magnet within a float and a magnetic reed switch contained within a secure housing. The float moves with the change in liquid and will cause the reed switch to either open or close depending on if it’s in air or liquid. Although simple in design, this technology offers long-term reliability at an attractive price point. It has amazing features like non-powered, direct indication, relatively inexpensive, various outputs.
Vibrating Level Switch –
The vibrating sensor technology is perfect for solid and liquid level control, including sticky materials and foam, as well as powders and fine-grained solids. These are compact and cost-effective. It can be used for level control of liquid, powders and fine-grained solids within mining, chemical processing, and food and beverage industries.
Rotary Paddle Level Switch –
Rotary paddle switch is used as a full, demand or empty detector in storage silos or process vessels and is suitable for use in almost all solids. With its simple electromechanical measuring principle it can also be adapted for extreme process conditions. A motor-driven shaft causes the vane to rotate. Once the material level reaches the vane, thereby preventing further rotation, this creates a torque, which is converted via a switch to an electric signal. Once the vane is free again of the material, the output signal is reset and the motor-driven shaft rotates again.
Probe Type Level Switches –
Probe type level sensors operate in the way that process fluids have dielectric constants, significantly different to air. They measure the change in capacitance between two plates produced by changes in level. Capacitance level sensors work with a range of solids, liquids, and mixed materials. They are also available in contact and non-contact configurations meaning some of which can be attached outside the container/tank.