GB272914A - Improvements relating to the detection of suspended matter in fluids and the operation of means for indicating its presence - Google Patents

Abstract

272,914. Kidde & Co., Inc., W., (Assignees of Freygang, W. H.). June 17, 1926, [Convention date]. Light radiations, control of apparatus by.-In a method for giving automatic warning of the presence of suspended matter in fluid, for example smoke, light is directed by the suspended matter by reflection and/or refraction upon a normally non-illuminated light sensitive element, for example a photo-electric cell, arranged in an alarm circuit. As shown in Fig. 1, smoke-laden gases are drawn from spaces to be protected by pipes 3 and pass through tubes 5 to a detection chamber 6. At one side of this chamber is a light-sensitive cell 1 in a casing 2 having a window 11. Light from a source 8 is directed through the tubes 5 by suitable lenses and mirrors, and is reflected or refracted by the suspended particles upon the cell 1, energizing the latter and operating an alarm. As shown in Fig. 6, the cell 1 is in circuit with a resistance 14, battery 13, and relay 21 through a three-electrode thermionic amplifier 16. The relay 21 is in circuit with a battery 25 and bell 24. In a modification, the light from the source 8 is concentrated to a parallel beam travelling across the path of gases issuing from a single smoke pipe. In modifications of the first arrangement, the reflected light is concentrated on the cell by a parabolic mirror, or by a lens arranged in the window of the casing 2. In another modification, several sensitive cells are provided, light from the source 8 being distributed by a lens system. Specification 191,856, [Class 47 (ii), Fire-extinguishing &c.], is referred to.