Patent GB-834416-A (GB)
Title: Alarm system and signalling apparatus therefor
Inventor: SPERRY ALBERT F
IPC: G08B17/04
Filed: 1956-04-24
Abstract: 834,416. Visible signalling apparatus; temperature alarms. PANELLIT Inc. April 24, 1956, No. 12477/56. Classes 118 (1) and 118 (2). [Also in Groups XVIII and XIX] In a fluid-pressure operated alarm system comprising a plurality of indicator units, Fig. 2, mounted upon a panel 11, Fig. 1, and associated with respective sensing units, the occurrence of a predetermined abnormal condition in the region of a sensing unit causes a change in fluid-pressure to occur within bellows 19 thus releasing a sector-shaped indicator 24 which is urged to a first position in which a coloured portion 24a gives an alarm indication, further means being provided whereby an attendant on receipt of the alarm indication can release the indicator from its first position whence it is urged to a second position in which a differently coloured portion 24b is visible, means also being provided whereby when the abnormal condition giving rise to the alarm indication has been remedied the attendant can cause the corresponding indicator 24 to return to its normal position behind the panel 11. When any one indicator is in the first position with portion 24a visible an audible alarm is also given from whistle 55; this ceases when the indicator is moved to the second position. In the arrangement illustrated the occurrence of a predetermined abnormal condition (e.g. of pressure, temperature, liquid level, or rate of flow) causes valve 14, Fig. 2, to close whereby the pressure in bellows 19 in. creases and the bellows expands to tilt a beltcrank lever 37 and release a lever 40 the tip of which engages in a pawl recessed in the surface of a sleeve 22 secured to shaft 23. Shaft 23, which is spring-urged in an anticlockwise direction consequently rotates until the pawl is caught by an arm 42 in which position portion 24a of indicator 24 projects from the indicator housing. The pressure on arm 42 causes a rearward extension thereof to leave the open end of a pressure conduit 48 where it normally rests and engage instead the end of a slide 44. The release of pressure in the conduit 48 causes a bellows 53, Fig. 1, to collapse withdrawing a rod 54 thereby completing the circuit from a pressure source to whistle 55 through a valve 50. On the receipt of an alarm indication the attendant moves the corresponding one of levers 56 upwardly thus drawing rod 58 downwardly and causing slide 44 to be withdrawn thus allowing the arm 42 to turn further clockwise and release its engagement with the pawl on the sleeve 22. The indicator 24 is then further rotated to expose its portion 24b, the arm 42 returning to its original position and its rearward extension closing the end of conduit 48 to stop the whistle 55. When the fault causing the original indication has been corrected the unit may be restored to its original condition by raising a corresponding lever 65 which pulls on a cord 28 to rotate the shaft 23 against the action of its spring until the pawl on the sleeve 22 engages once more with the lever 40. Levers 67 and 68 are also provided, actuation of lever 67 causing the simultaneous actuation of all the levers 56 through the transverse rod 70 and actuation of lever 68 causing the simultaneous actuation of all the levers 65 through the transverse rod 71. A transparent cover 72 is provided for the indicators 24 on the panel 11.