GB354384A - Improvements in apparatus for observing smoke from boiler or other furnaces - Google Patents

Abstract

<PICT:0354384/III/1> <PICT:0354384/III/2> <PICT:0354384/III/3> A beam of light is projected across the path of the gases leaving a furnace and is then analysed into its spectrum, changes in the spectrum indicating the presence and density of smoke. Light from a lamp so passes across the flue or chimney d into a pipe p<1> and is deflected by a prism rp on to an analysing prism ap placed so that the spectrum can be seen by the furnace operator. Emission of smoke causes first the yellow and then the blue to be cut out, and the fire is adjusted accordingly. The curved front glass or lens projects into a clearance hole in the flue wall so that it is kept clean by air leakage into the flue. To stop considerable leakage of air into the flue through the pipe p<1> a removable transparent glass sheet s, Fig. 4, is interposed, space being left to allow a small leakage of air for cleaning the glass. The deflecting prism rp is carried by a plate pl fixed to a ring r adjustable on the pipe p<1> and retained in adjusted position by a set pin sc. The prism is adjusted regularly by a wing nut wn<1>. The analysing prism ap is similarly adjusted and is provided with a sheet metal hood. By using a compound prism the light may be viewed in a direct line with the lamp. A transformer t supplies the lamp which is of the low-voltage type with a concentrated filament. When using a lamp having an extended filament a piece of fine screening glass is cemented or clamped on the inner face of the front glass or lens. According to the Provisional Specification the light may fall upon a mirror or a screen of frosted glass.