GB480330A - Improvements in or relating to blasting cartridges and charges - Google Patents

Abstract

480,330. Blasting cartridges ; explosives. IGNATIEFF, A., and HEATERS. Ltd. Aug. 18, 1936, No. 22782. [Classes 9 (i) and 9 (ii)] Relates to blasting-cartridges and charges of the kind comprising a pressure-resisting container wherein a gas which does not support combustion, such as carbon di-oxide, is confined under pressure by a sealing device capable of being suddenly opened under an increase in internal pressure and a combustible gas-producing charge in the container, together with means, such as an electrically fired fuze to ignite the charge, whereby, upon combustion of the charge, the pressure within the container rises to a point at which the sealing device opens and releases the compressed gas. According to the invention, the gas-producing charge employed comprises a self-combustible mixture comprising an oxidizer and a fuel in admixture with a non-combustible constituent (which upon combustion of the charge is' capable of yielding gaseous products) in a proportion sufficient. to render the charge not self-burning in the open but capable of rapid combustion when confined in the presence of the gas. The non-combustible constituent, which may consist of ammonium oxalate or phosphate, magnesium chloride or sulphate, zinc sulphate or sodium bicarbonate, is preferably such as to afford a large volume of gaseous products with but a small or no solid residue, whilst the self-combustible mixture may contain a considerable excess of the oxidizer over the fuel. According to one example, the gas-producing charge comprises 60 parts by weight of potassium perchlorate, 9 parts by weight of salicylic acid, 1 part by weight of castor oil and 30 parts by weight of ammonium oxalate. The proportion and grain size of the non-combustible constituent can be varied, the amount of ammonium oxalate ranging from 18 to 43 parts by weight of the mixture. If desired, the excess of potassium perchlorate may be replaced by ammonium nitrate. Amongst other examples given, the charge may consist of (a) potassium perchlorate, starch, borax, castor oil and ammonium oxalate or (b) potassium chlorate, charcoal, magnesium sulphate and castor oil. Specifications 397,203, 413,823, 415,026, and 430,258 are referred to.