GB695908A - Improvements in or relating to blasting cartridges and initiators therefor - Google Patents

Abstract

695,908. Blasting cartridges. IMPERIAL CHEMICAL INDUSTRIES, Ltd. Jan. 21, 1952 [May 11, 1951], No. 11130/51. Class- 9(i) A fluid pressure blasting cartridge has a body 1 of high' tensile steel separated from a venting head 2 by a mild steel disc 3 yielding at a pressure of the order of 15 tons per sq. in. Through a fir- 'ing head 4 is led an insulated lead wire 5 connecting a terminal 6 to a ball contact maker 9 and hence to a fuzehead 16 in a fireproofed cardboard cylinder 11, the return circuit to a terminal 8 being through 'the firing head. The cylinder 11 contains a blackpowder charge 18 surrounding a copper sleeve 13 closed at one end by a neoprene plug 17 through which passes the leads 19, 20 to the fuzehead. The .lead 19 terminates in a spring 31 contacting the ball contact 9, while the lead 20 is connected to a flanged copper ring 10 surrounding a wooden plug 21. At the other end the copper sleeve is crimped to an instantaneous fuze cord 22 which passes through a wooden closure plug to a second blackpowder charge 27 in a fireproofed cardboard container 24. This second charge has a higher rate of burning than the first and is held in its container by wooden plugs 25, 26. The main charge 28, which surrounds the initiating charges is a gasproducing mixture comprising sodium nitrate, ammonium chloride and magnesium oxide. On passing a current through the fuzehead, the blackpowder charges are ignited practically simultaneously, with the result that decomposition begins simultaneously at both ends of the gas-producing charge.