GB264820A - Improvements in and relating to mercury vapour detectors - Google Patents

Abstract

264,820. British Thomson-Houston Co., Ltd., (Assignees of Nordlander. B. W.). Jan. 21, 1926, [Convention date]. Tell-tale apparatus.-In apparatus for detecting and estimating mercury vapour in gases, such as air or flue gases, by subjecting a mercury-sensitive reagent to a current of the gas at a predetermined temperature, means are provided for giving a visual indication at a remote point of the result of the test and for sounding an alarm when the mercury content of the gas is dangerously high. The gas is delivered through a tube 33 into a chamber 32 and thence into a conduit 30 which directs it on to the reagent, whereafter it leaves the apparatus through a chamber 31 and tube 50. The tube 30 is provided with a thermostatic device (not shown) which regulates an electric heater (also not shown) in the tube 33. The mercurysensitive reagent comprises selenium sulphide applied to a, transparent film 35 which is wound from a reel 36 on to a reel 37. A beam of light from a lamp 39 passes through the film to a photoelectric cell 40, and in accordance with the darkening of the film by the action of the mercury, the output circuit 42 of the cell is affected. This circuit contains a battery 43 and an electric measuring device, such as a galvanometer 44, which gives a visual indication of the mercury content of the gas. When the mercury content of the gas is dangerously high, the pointer 45 of the galvanometer 44 touches a contact 46 and so completes a circuit including an alarm 49. The output circuit 42 may be an amplification circuit.