Level Switches

Table of Contents

What are Level Switches?

A level switch is a way to detect the level of a liquid, powder or granulated materials in a container. There are few different types of level switches but they all serve the same purpose. When the conducting liquid reaches the height of the electrodes, the circuit is changed or completed and will output a signal to do something about it. You can have a level switch for low level detection for when the depth becomes too low, the circuit is broken and the signal is lost [1].Level switches are used in a large variety of applications such as oil tanks, washing machines, and wells [2].

Types of Level Switches

There are three basic different types of float switches you can use, depending on the application.

• One type of level switches is a float switch. The switch floats on top of the liquid and responds to the level moving up or down with an internal sensor in the switch. This sensor can complete a circuit to form an alert for the surface level of the tank
• The second type of level switches is a capacitance switch. This works by having a probe hanging from a certain height into the tank, forming a two plate capacitor with the wall of the tank and the probe. When the level reaches the probe, a the capacitance changes between the probe and the wall due to the differing dielectric constant for the liquid compared to air. This triggers a change in the circuit for an alert to the changing level of liquid.

• The last type of level switch is a vibrating switch. This works by utilizing 2 hanging vibrating prongs, and when the liquid reaches the prongs, their frequency changes. A device picks up this change and sends an alert [3].

  Figure 1: A basic float switch [4]