It operates on the basic buoyancy principle .It uses float that glides on the surface of liquids. This level switch consists of – Terminal Enclosure, Float Stem with Hermetically sealed Reed Switches and Float with magnets assembled inside. As the float rises or falls with liquid level, the internal magnet moves in or out of the field of the switch resulting in its opening or closing. A non-magnetic barrier tube containing the reed switch isolates it from the process. These type level controls are available for controlling level at up to four different
preset locations and can virtually be made of any length. This switch is highly effective and cost shedding and also finds use in a wide range of industries.