Float level switches are mainly employed for level measurement in narrow level differential fields, for example high level alarm or low level alarm applications. One of the significant types of float is a magnetrol float level switch which consists of a plain float and operates via a magnetic coupling action.
The switch is designed in such a way that some part of float remains submerged in the liquid as it rides on the liquid surface. The float goes up and down on the surface depending upon the level of fluid in the tank. This causes a magnetic sleeve to travel in or out of the region of a magnetic switch resulting in its activation.
A non-magnetic tube is also provided in the design which acts as a barrier and helps in separating the switching arrangement from the controlled fluid.