GB354419A - Improvements in apparatus for the detection of smoke from furnaces - Google Patents

Abstract

<PICT:0354419/III/1> One or more spark gaps p are arranged in a flue d in the path of the flue gases and connected to the secondary winding of a transformer or spark coil T, current variations in the primary winding of which, upon passage of sparks, are used to give visible or audible warning of the presence of smoke. The primary winding is in series with a limiting resistance r and the magnet coils m<1>, m<2> of a relay Y. Normally the armature a of the relay is held by a spring g against a stop s but when a spark passes due to the presence of smoke the increase in the primary current attracts the armature closing a circuit supplying lamps l<1>, l<2>, and an electric hooter or bell k. The lamps may be embodied in a sign as shown. The lamps and hooter may be connected directly in series with the primary winding of the transformer. The relay may be connected across the limiting resistance r, or across the primary winding. Two or more sparking plugs in different flues may be connected in parallel. The potential across the spark gap may be adjusted by a switch which puts more or less turns in the primary circuit, and such switch can be calibrated according to various densities of smoke and marked "Haze," "Medium," and "Heavy." Tappings may be taken from the secondary winding to vary the potential across the spark gap. According to the Provisional Specification the warning device may comprise luminous discharge tubes, an ammeter or a voltmeter, and the relay may include a coherer.