Liquid level monitoring and control apparatus

A liquid level monitoring and control apparatus is described, which generates an alarm signal or a safety signal, discontinuing an operation such as heating, when the liquid level in a controlled vessel has reached a predetermined level. Several signals, similar or different, may be generated at different liquid levels. The operation of the. apparatus may be based on various physical properties, such as optical, magnetic, acoustic, electrical and conductivity properties. The apparatus comprises a floating actuator, the level of which is determined by the level of the liquid in the vessel, a sensing assembly comprising at least a member which can be actuated by the actuator, means for guiding the vertical displacement of the actuator and means for issuing the desired signal or signals when the actuator reaches a level close to that of the actuatable member. The actuatable member can be displaced to set the predetermined level of the liquid as desired by the user. The apparatus can be so designed as to constitute a transportable kit comprising the actuator and the actuatable member. In a form of the invention, the actuator is mounted on a floating rod. In another modification of the apparatus, the meniscus of said liquid serves as the actuator.