Level switches are most often used in applications where there is a certain level that is important to detect by the process controller. The level switch has a float attached that mechanically switches without the need for a power supply. This means that level switches work independently of foaming, conductivity, dielectric, pressure, vacuum, temperature, vapours, condensation, bubble formation, boiling effects and vibrations and are suitable for almost all liquid media.
The contact switching can always be adjusted according to the process. There is always the Normally Open (NO) function or the Normally Closed (NC) function. Normally open means that the contact is intact unless the switch switches. Normally closed is the other way around, meaning that the contact is normally closed but when the switch switches the contact opens. When the level rises or falls back to the level of the initial function, the contact opens or closes again according to the function.
As the most common variant, this version uses a vertical installation to switch according to the level in the tank or process. The float can be attached on a cable or stem and can be made out of a large range of materials, according to what best suits the process conditions. There are also floats attaches to a reed that switches when the float is so far away that it activates the magnet at the end of the float rod.
Horizontal switches use an arm with the float attached to follow along with the liquid level and switch when the arm is pushed up or down as much as it can go. The operating principle is the same as with the vertical level switch, but the horizontal layout means that a longer service life is usually achieved.