GB270123A - Improvements in or relating to fire alarm devices - Google Patents

Abstract

270,123. McCandlish, W. H. July 9, 1926. Alarms operated by fusible devices; electric alarm circuits. -A fire alarm device, preferably a modified push switch of an ordinary electric-bell circuit, is adapted for manual operation and also for automatic operation by an independent spring when a fusible member melts. In the hanging switch shown in Fig. 1, a casing j has a head k carrying electric contacts l<1>. A movable contact b is carried by a stem a guided in a frame c<1>. On the stem a are a collar b and a disc e held apart by a spring d. The stem and parts carried by it can be pushed inwardly against a spring h to close the circuit bv means of an open frame e<3>. When a fusible collar f on the stem melts, the latter, without the disc e, is moved inwardly to close the circuit, by the spring d. The contact b is mounted for oscillation on the stem a to ensure contact with all the points l<1>. The open frame e<3> permits ready access of heat to the sleeve f, and also replacement of the sleeve by removing a nut g. The casing j may have flanges for attachment to a ceiling. In a modification, Fig. 4, for attachment to a wall, a base part j<5> carries contact points l<1> and a cap j<6> carries a plate spring n against the pressure of which a contact b can be forced inwardly by hand. Fusion of a sleeve f again permits the stem a to be moved inwardly by the spring d. In a modification of this form, the spring n is carried by the base part and is connected to one of the electric leads l<2>, the other lead being connected to a single contact l<1>. In this case, the circuit is closed through the spring n, stem a and contacts b, l<1>. The thermal device described is preferably embodied in an ordinarv call-bell circuit in combination with an external circuit and bell controlled by a switch which is closed, for example at night, when the street door is closed.