GB771900A - Improvements in energisers for blasting cartridges - Google Patents

Abstract

771,900. Blasting cartridges. SHIMMIN, T. A., BRAY N., and CARDOX (GREAT BRITAIN) Ltd. Dec. 21, 1955 [Jan. 5, 1955], No. 295/55. Class 9 (1). A fluid-pressure blasting cartridge is provided with an energizer for the gas-producing charge, the energizer being a container housing a gas-producing composition which will not burn under normal temperatures and pressures and cannot be ignited by a resistance wire when the pressure is substantially less than 100 atmospheres. An energizer for a blasting cartridge as in Specification 654,958 comprises a paper or cardboard container 1 closed at one end by a metal cap 3 and at the other end by a plug 2, which may be of wood. An electric fuzehead extends from the plug into the gas-producing composition and consists of metal foil electrodes 5 secured to an insulator 4 e.g. pulp board and connected by a bridge wire 6. The electrodes are surrounded by a sleeve 7 and one is connected by a lead 8 to the cap 3 and the other by a wire 9 to a conductor (not shown) in the cartridge casing. The gas-producing composition may be potassium perchlorate 59-62 parts, salicylic acid 8.5-10.5 parts, ammonium oxalate 27.5-29.5 parts and castor oil 1-3 parts, all parts being by weight. The composition is compacted so that there is at least 4.5 gms. in the half-inch length surrounding the wire 6, when the diameter of the tube is 0.75 ins. The bridge wire 6 may be 1 mm. of nickel chrome wire having a resistance of 1000-2000 ohms/metre. The tube 1 and plug 2 may be made from synthetic plastics. Specifications 480,330, 560,227, 617,136, 630,981, and 668,277 also are referred to.