Apparatus for indicating the presence of smoke or dust in air

Abstract

Abstract 394,853. Actuating apparatus by light radiations. STEPHENS, A. J., 285, High Holborn, London.-(Walther et Cie Akt.- Ges.; Dellbruck, Cologne, Germany.) Oct. 10, 1932, No. 28232. [Class 40 (v).] In an installation for detecting smoke or dust, of the kind in which a current of air is caused to pass between a photo-electric cell and a source of light, use is made of a cell of the semiconductor type, that is, a cell which generates an E.M.F. when exposed to light. As shown, the cell e is arranged at one end of a tube a through which the current of air passes, and is permanently illuminated by a lamp d. The current generated by the cell deflects the pointer h of a galvanometer g. When smoke is present in the tube, the cell current falls and the pointer h closes a signal circuit (not shown). The normal deflection of the pointer indicates the condition of the installation, which can further be tested by means of an opaque body k movable into position in front of the lamp d. Means may be provided for interposing the body k automatically at intervals. In a modification, two cells e are arranged as two arms of a Wheatstone bridge, one of the cells being so placed that it is not influenced by the presence of smoke. 'The galvanometer is arranged across the bridge, and a small current normally flows in it. In other modifications, lenses or mirrors are associated with the light source. In one such arrangement, the mirrors cause the light beam to follow an extended path before impinging on the photo-cell. The galvanometer may be arranged to signal the extinction of the lamp or damage of the apparatus. The galvanometer g may be replaced by a recording instrument.

Inventors

No inventors recorded.

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