Abstract: The present invention relates to an emergency supervisory system which comprises a plurality of supervisory apparatus provided for respective supervisory regions and connected in parallel with each other to signal lines derived from a central signal station; and switching devices which are provided at positions for separate the supervisory apparatus from each other and adapted to be closed normally and opened upon detection of short-circuiting to separate the supervisory apparatus adjacent thereto from the lines, thereby to supervise an emergency such as a fire through one or both of the signal lines.

Abstract: A fire detector and a fire alarm system wherein a plurality of fire detectors are connected across a pair of lines leading to a signal station and which is capable of detecting, at the signal station, removal of a detector head or heads from an associated socket or sockets of any one or more detectors and yet capable of keeping the succeeding fire detectors operative to send a possible fire alarm signal even after removal of the head or heads. Each of said fire detectors comprises a means for disconnecting the line connected therethrough to the succeeding detector, temporarily in the course of removal of the detector head or heads from the associated socket or sockets or periodically after the detector or detectors has or have been removed from the associated socket or sockets. The signal station comprises a means for detecting the temporary or periodical disconnection of the line.

Abstract: A fire alarm having in a single unit a battery and a fire detecting section energized by the battery to detect abnormal environmental conditions such as heat and smoke to provide an output signal. A voltage decrement detecting section detects a voltage decrement of the battery to provide an output signal. A warning unit such as a buzzer is coupled to a switching circuit for operating the warning unit upon reception of the output signal from either the fire detecting section or the voltage decrement detecting section through an input terminal thereof. To reduce power consumption, the system uses a multivibrator having C-MOS IC, inverters.