GB508931A - Improvements relating to fire or heat detecting and alarm apparatus - Google Patents

Abstract

508,931. Fire alarms. SIDDALL, W. H., SIDDALL, J., and SIDDALL, W. M. Jan. 20, 1939, No. 2076. [Class 40 (i)] [Also in Group XXI] The motor of an electric clock and a fire dectector including at least one normally closed thermo-responsive circuit controller are connected in series with a source of electricity so that failure of the supply of electricity or impairment of the circuit between the source and the fire detector conductors will be indicated by the stopping of the clock, and an electrical signal initiating mechanism which is operatively responsive to the opening of the circuit controller or to an impairment of the circuit through the fire detector conductors to cause actuation of a signal device without stopping the clock. Mains M energize a transformer N, one terminal of the secondary coil being connected to one terminal of the field coil of the motor B of the electric clock. The other terminal of the field coil passes to a contact 6 co-operating with a contact 5 mounted on a device of the kind responsive to rapid rise of fluid pressure comprising tubing 1 covered with heat conducting and electric insulating material. The ends of the tubing are connected within the casing of the clock, by tubing having a breather 3 mounted on an insulating sheath into which project two ends of the tubing, and a device 26 of the kind described in U.S.A. Specification 2,027,068, wherein the circuit is opened on the occurrence of a predetermined temperature in the vicinity of the device. The tubing on the opposite side of the breather from the contact 5 is connected to a high resistance relay 11 having an armature 12, a contact 15, and one terminal of a low resistance electric bell 9, the other terminal of which is connected to the other terminal of the transformer. This last terminal is also connected through a lamp 17 to a terminal 16. The armature of the relay is adapted to connect the terminals 15, 16 and both with a lever 18 of a coding device comprising a wheel driven by the motor B and carrying protuberances 24. The lever carries a contact making and breaking a circuit through a resistance 20 with the first mentioned terminal of the transformer secondary. A failure of the electric supply is indicated by the stopping of the clock. Should the tube 1 break or a rise in temperature interrupt the circuit at 26 or between the contacts 5, 6, the relay is energized, the lamp and bell giving audible and visual signals coded by the protuberances 24. The resistance 24 prevents the current taken by the lamp and bell from stopping the clock. The small current taken by the clock is insufficient to ring the bell. In a modification, the tubing 1 may extend throughout a large area. In another modification, a wire connecting devices 26 in series is substituted for tubing.