GB403034A - Improvements in devices for automatically controlling fire doors - Google Patents

Abstract

403,034. Preventing and extinguishing fires. FISCHER, A. O., 35, Birkenstrasse, Bremen, Germany. June 22,1933, No. 17819. Addition to 394,179. [Classes 47 (i) and 47 (ii).] The means described in the parent Specification for releasing a self-closing door is modified by the use of a bimetallic spring as the thermal element. The door-holding latch 19 is urged to release the door by a spring 52 but its stem 16 extends into a casing and is held against movement by a train of levers 14, 11, 9. The lever 9 is locked by a sliding pin, 5. When a bimetallic spring 1 bends in case of fire, its free end engages the pin 5 and moves it against the resistance of a spring 20, so releasing the latch 19. The initial position of the spring 1 is adjustable by a screw 4, to vary the temperature at which the device will act. The levers 9, 11, 14 are shaped to facilitate resetting of the device after use. In a modification, Fig. 5, the adjustable bimetallic spring 25 is of spiral form, its free end having a pin 35 which locks an arm 36 against movement. Under heating, the free end of the spring 25 moves, releasing the arm 36 and so releasing a train of levers 41, 44, 48, 50 which normally locks the latch 19. When the lever 50 is released, it closes a switch 58 in an electric alarm or extinguisher-controlling circuit. In another modification, the latch is arranged vertically, and carries a resilient fork adapted to co-operate with a bolt on the door for holding the latter open.