GB337212A - Improvements relating to smoke indicating or recording appliances - Google Patents

Abstract

337,212. Associated Electrical Industries, Ltd., (Assignees of Vedder, E. H., and Erickson, E. 0.). Nov. 9, 1928, [Convention date]. Turbidometers. - A device for indicating the presence, or recording the density, of smoke, of the kind comprising a light source and a lightsensitive cell in circuit with indicating and/or recording devices, has the light source, and the light-sensitive elements arranged as dust and moisture-proof units rigidly connected in predetermined relationship by means of a tubular connection with a skeleton portion for the passage of smoke. As shown, Fig. 1, the light source 12 and the light-sensitive unit 13 are connected by a conduit 14, 18 which has a skeleton portion 21 arranged within a smoke conduit 17. The latter may be any type of smoke conduit, or a smoke stack, or any space where smoke would denote an abnormal condition requiring attention. The light source unit, Fig. 7, comprises an outer box 22, which is secured by bolts 41 to a flange 39 on the conduit 14, and an inner casing 23 which is dust and moisture-proof and is independently secured to the flange 39 by bolts 42. An openended conduit 40 with apertures 46 is secured between the conduit 14 and an opening in the casing 23, in which is a lens 43. The inner casing houses an ammeter 27, and a lamp 28 which is adjustably carried by brackets 29, 31. A tube 44 opens into the box 22. The light-sensitive unit is similarly constructed, and comprises an outer box 51, Fig. 5, bolted to a flange 53 on the conduit 18, and an inner dust and moisture-proof casing 52. A conduit 50 with apertures 72 is fixed between the conduit 18 and a lens 66 in the casing. The latter houses a rectifier 56, light. sensitive cell 58, thermionic amplifier 59, and ammeter 63. A screen 61 with a small aperture 62 is arranged between the cell 58 and the light source. A pipe 71 enters a box 51. The elements having been mounted in proper alignment, and the lamp 28 illuminated, smoke entering the skeleton portion 21 of the conduit 14, 18 will cause fluctuations in the output of the amplifier 59, which will be indicated by the ammeter 63. The latter may be connected to any suitable recording instrument. Air drawn into the boxes 22, 51 by the pipes 44, 71 passes through the apertures 46, 72 and so to the conduit 14, 18, preventing smoke or dust from reaching, and soiling, the lenses 43, 66. In order that movements of the walls of the smoke conduit 17 shall not throw the elements of the device out of alignment, the conduit 14, 18 is supported resiliently where it passes through the said walls.