GB355630A - Improvements in apparatus for the detection of smoke from furnaces - Google Patents

Abstract

A spark gap is arranged in the path of the flue gases from a furnace and connected to a source of high potential and to a luminous discharge lamp or tube such as a Geissler or neon tube so that when a spark passes due to the presence of smoke <PICT:0355630/III/1> <PICT:0355630/III/2> <PICT:0355630/III/3> the lamp or tube is energized. A sparking plug p projects into the flue passage or chimney d and is connected to the secondary winding of a transformer tf the other terminal of which is connected to earth through a luminous discharge tube formed into the word " Smoke." A variable capacity vc may be connected across the high tension lead to the sparking plug and earth to adjust the potential across the tube nearly to glow point when no smoke is passing, making the apparatus more sensitive. This variable capacity may comprise a metal rod sliding inside a glass tube fixed within a metal tube. A limiting resistance r is provided in series with the primary winding of the transformer. Several chimneys d<1>, d<2>, d<3>, Fig. 2, ma be provided with sparking plugs p<1>, p<2>, p<3> connected in sequence with the transformer secondary by a rotary switch rs driven by an electric motor. Neon lamps n<1>, n<2>, n<3> are provided in each lead to the sparking plugs to indicate to the operator which chimney is smoking, or these lamps may each comprise a neon tube in the form of the word " Smoke." The sparking plug projects to the centre of the chimney and comprises an outer glass tube ot, Fig. 4, carried by a metal fitting f screwing into the wall of the chimney, and an inner glass tube i containing a pointed rod pr. The outer electrode oe is clamped to the tube ot at C and connected by a wire w to the metal fitting f. To prevent alteration of the length of the spark due to expansion of the rod pr a spring s holds a nut u on the rod against the end of the tube i. A glass bushing holds the inner tube i centrally within a nipple np screwing into the fitting f and by turning the nipple the spark length can be adjusted, a lock nut ln securing it in adjusted position. Holes h admit air to the space between the glass tubes to sweep away soot particles, a bead b on the inner tube deflecting the air away from the spark gap. The outer electrode may have more than one sparking point. The potential across the sparking plug may be varied by a switch which may be calibrated in various densities of smoke.