KOBOLD bypass level switches of model NB are used when, for example, level monitoring in the bypass is needed due to lack of space (with agitators) or at high temperatures. The instrument comprises a metal housing with internally mounted magnetic level switch and operates on the principle of communicating tubes. As soon as the housing of the bypass level switch is about half full with liquid, the float moves to the top and operates with the internal ring magnet a changeover contact fitted in the measuring tube. Solenoid valves, signal lamps or pumps are switched by the changeover contact by means of suitable electrical auxiliaries (relay, contactor relay).