GB588613A - Improvements in or relating to blasting assemblies and to delay devices for use therein - Google Patents

Abstract

588,613. Blasting-fuzes and detonators. DU PONT DE NEMOURS & CO., E. I. Aug. 8, 1944, No. 15081. Convention date, Aug. 7, 1943. [Class 9 (i)] A delay device connecting two lengths of detonating fuze for blasting comprises an ignition charge 3 ignited by one length of detonating fuze 2, and adapted to ignite a relatively slow-burning composition 5 which after the desired delay ignites an explosive charge 7 which detonates the second length of detonating fuze 8. The charge 3 may be omitted. The detonating fuze is pentaerythritol tetranitrate. The ignition charge 3 is contained in the constricted end of a steel container 4 and comprises mercury fulminate potassium chlorate nitrostarch and charcoal made into a paste with a solvent. The slow - burning composition 5 comprises 88-12 blend barium oxide and magnesium and is enclosed in a copper shell 6 also containing the compressed explosive charge 7 of 80-20 mixture of mercury fulminate and potassium chlorate. The whole is surrounded by a cardboard tube 9 clamped by bands 10. The detonating fuze may be that known under the Registered Trade Mark " Cordtex." The composition 5 may comprise barium oxide and selenium, potassium permangan ate and antimony, or a gas-producing composition such as black powder and nitrocellulose. The charge 7 may comprise lead azide, nitromannite or diazodinitrophenol, The delay device is used in the detonating fuze connecting rows of explosive charges parallel to a quarry face to allow these rows to be fired successively.