GB728240A - Cord-like ignition devices for explosive charges - Google Patents

Abstract

728,240. ignition devices. IMPERIAL CHEMICAL INDUSTRIES, Ltd. June 19, 1953 [Sept. 22, 1952], No. 23690/52. Classes 9(1) and 9(2). In a cord-like ignition device comprising a combustible flexible envelope 7 surrounding at least one incendiary element 1 and at least one wick element 4 and having therein continuous spaces along its length, the envelope is waterproofed with a waterproof non- detonating combustible composition, said incendiary element comprises a coherent mass of a non- detonating deflagrating composition of low gas evolution characteristics and high heat emissivity comprising a homogeneous mixture of oxidising and reducing agents bound together by a non- detonating thermoplastic medium and said wick element comprises at least one combustible filamentary portion impregnated with and surrounded by a fast-burning non-detonating gas-producing deflagrating composition. In one example, all parts being by weight, the incendiary element is made by extruding round a 36S.W.G. copper wire 2 a composition consisting of 26À2 parts plasticised nitro-cellulose, 0.5 parts diethyldiphenylurea, 23 parts red lead, 10.5 parts potassium nitrate, 22.2 parts potassium perchlorate, 4.4 parts silicon, 8.3 parts calcium silicide and 4.9 parts flake charcoal; the diameter of the element being 0.04 inch. The plasticized nitro-cellulose consists of 50 parts nitro-cellulose containing 11.8-12.3 per cent nitrogen by weight and giving a solution having a viscosity of 6 to 15 poises when 40 g. are dissolved in 100 ml. of acetone containing 5 per cent by weight of water, 48 parts of dibutyl phthalate and 2 parts diphenylamine. Each wick element is 0.043 of an inch and comprises three filaments each consisting of two cotton threads of number 16 count spun together. The filaments are passed through a composition consisting of 30 parts nitrocellulose solution and 20 parts of a sulphurless mealed black powder, and are then spun together ; the solvent being finally removed by heating. The nitro-cellulose solution consists of 170g. nitrocellulose having a nitrogen content of 11.8- 12.3 per cent by weight and giving a solution having a viscosity of 3-5 poises when 40g. are dissolved in 100 ml. of acetone containing 5 per cent by weight of water, 180 ml. industrial ethyl alcohol and 160 ml. acetone. The envelope comprises a Kraft paper tape 7 which is bound by textile filaments 8, 9 and coated with a composition used for the wick elements. The diameter of the ignition device is .12 of an inch and its burning speed is 2 feet per second. The copper wire may be replaced by at least one cotton thread or dispensed with and the wick element may be a paper string consisting of a number of filaments spun together. Either side or both sides of the flexible envelope may be impregnated with the waterproofing composition. Specification 652,542 is referred to.