Patent GB-426599-A (GB)
Title: Improvements in and relating to apparatus for the detection of suspended matter in fluids
IPC: G08B17/10
Filed: 1934-08-31
Abstract: 426,599. Smoke detectors. KIDDE & CO., Inc., W., 60, West Street, Bloomfield, New Jersey, U.S.A. Aug. 31, 1934, No. 25112. Convention date, Sept. 6, 1933. [Class 47 (i)] Relates to installations for detecting smoke or other suspended matter in fluids of the type comprising conductors for drawing fluid streams from separate spaces, means for permitting visual inspection of the streams, and automatic means for detecting and signalling the presence of smoke in individual streams ; and consists in arranging that the individual streams are successively diverted to the detecting means before they are subjected to visual inspection, and can be directed back to the visual station at any time. Electromagnetically operated valves controlled by a selector device are provided for diverting the streams, any valve being arranged to remain in diverting position, when smoke is detected in the stream it controls, until released by a manual switch ; means also are provided for the electrical supervision of the installation, and for preventing false smoke alarms due to failure of parts of the installation. Conductors 2 from the separate spaces lead to visual inspection devices 4 arranged in a common chamber 5 connected at 10 to a suction fan 7. The devices 4 comprise light beams which are not visible at the individual window 12 or common window 6 until smoke is present in the streams. A valve 3 in each conductor 2 normally is biassed to open passage to the corresponding device 4, but can be moved by an electromagnet 20 to divert the fluid stream to a detecting device 15 comprising a light source 19 and a photo-voltaic cell 18, the device 15 being connected to the fan 7 at 16. As shown in Fig. 3, the electromagnets 20 of the valves 3 are successively energized from a source of current POS, NEG through a selector switch arm 22 which is driven by a motor 33. Circuit from the current, source through the motor normally is completed through a cut-off switch 25, buzzer switch 29, terminals A and terminals C. Circuit to the several electromagnets 20 is completed in turn through the switches 25, 29, terminals A, automatic circuit breaker 44, and selector arm 22. The circuit-breaker 44 is operated by the motor 33 in time with the selector arm 22 so as to break the electromagnet circuit just before the arm 22 moves from any contact 21, thus avoiding arcing at the contacts 21. The light source 19 is energized through the switches 25, 29, a relay 52, and wires 53, 55, 38. If the source 19 fails, the relay 52 is de-energized, opening of the contact 58 then breaking the circuit of the main smoke alarms 70, 96 to prevent false alarms, and closing of the contact 59 closing an energizing circuit through trouble alarms 60, 61. A current insufficient to operate the smoke alarm gong 70 is maintained through the latter through a circuit including a relay 67 and the contact 58 of relay 52. Failure of the gong circuit releases the relay 67 to complete a circuit at 75 through the trouble alarms 60, 61. The E.M.F. normally generated by the cell 18 controls a galvanometer relay G, R. When smoke occurs, a circuit is closed at 77 through the switches 25, 29 and a relay 79. Energization of the latter closes contacts 83, 84, 85 and opens contact 86. Closure of contact 83 closes a circuit through an electromagnet 90 which then acts to disconnect the pawl which normally drives the selector switch 22, so that the fluid stream in which smoke has occurred remains diverted through the detector 15. Contact 84 closes an energizing circuit through the smoke alarm lamp 96, and contact 85 closes a circuit through the gong 70. Opening of the contact 86 breaks the energizing circuit of the trouble alarms 60, 61. Switches 29 and 72 enable the gongs 60 and 70 to be put out of action, while leaving the lamps 61 and 96 energized. The switch 29 is also adapted to break the circuits of the motor 33, electromagnets 20, lamp 19 and gong 70. Thus, in case of any derangement of the installation, the entire automatic system can be put out of action, leaving the visual station effective and the trouble lamp 61 alight. Opening of the main switch 25 puts the lamp 61 also out of action. The driving gear for the selector switch, Fig. 4, comprises a shaft 103 carrying the arm 22 and a ratchet 99 driven by a pawl 100 which is actuated by a cam 101 driven by the motor 33. The cam also operates a lever 107 to actuate the circuit breaker 44. The electromagnet 90 acts, when smoke is detected, to raise a yoke 106 to disengage the pawl 100 from the driving ratchet 99. The energizing circuit of the electromagnet 90 may be broken by a hand switch 89, Fig. 3, to allow driving of the selector switch to be resumed. A drum 104 mounted on the shaft 103 carries suitable indicia which are visible at the control station for showing which conductor 2 is, at any moment, connected to the detector 15. Similar indicia are associated with the visual devices 4. Specifications 146,298 and 191,856, [both in Class 47 (i)], are referred to.