A float with a permanent magnet moves along with the liquid level in a guide tube. The guide tube containes a reed contact (inert gas contact) which is triggered by the float magnet through the non-magnetic walls of the gloat and guide tube. By using magnet and reed contact, the switching process is contactless, wear-free and without auxiliary energy. The contacts are potential-free. Float switches are also available with several switching
points. The switching functions always refer to a constantly rising or falling liquid level (change over contact). By using a float for max. 2 switching points, a bi-stable switching behaviour is achieved, i.e. the switching state is maintained even if the level continues to rise or fall beyond the switching point. The float switch is easy to install and maintenance-free, i.e. the installation, commissioning and operating costs are low.