GB735407A - New and improved blasting initiator - Google Patents

Abstract

735,407. Blasting detonators. IMPERIAL CHEMICAL INDUSTRIES, Ltd. May 7,1954 [Sept. 1, 1953], No. 24145/53. Class 9(1). A blasting initiator, see Figs. 1 and 3, comprises a container 1, closure means 12, 13, 14 therefor, a screw cap 3, an electric detonator 9 having its base in close proximity to an explosive charge having a high velocity of detonation and means 6 externally of the container to position at least one length of detonating fuze in proximity thereto, the leading wires of the detonator passing through the closure means and a portion of said container being adapted on firing to permit the initiation of said fuze. The means 6 may comprise a brass plate which is screwed on to the container and provided with one or more rows of holes or a projection formed integral therewith. One length of fuze may be passed through each hole or a double length of fuze passed through adjacent holes in the plate. The closure means may comprise at least one resilient washer and preferably comprises one resilient washer compressed between two rigid plugs of different sizes. As shown, the wires pass through a " Tufnol " (Registered Trade Mark) disc 12, a washer 13 of rubber or neoprene and a " Tufnol " plug 14. The container is constructed so that it is totally destroyed by the firing of the detonator or is provided with a frangible portion. The container and cap may be made of steel or brass. The detonator may be a No. 6 detonator or comprise a metal tube containing a pressed base charge of cyclotrimethylene trinitramine on top of which is pressed a mixture of lead azide, lead styphnate and aluminium, above which is a pressed charge of a corned mixture of lead dinitroresorcinate and potassium chlorate on which lies a loose charge of the same composition in which sits an electric bridge wire ; the leading wires of the latter passing through a neoprene plug crimped to the tube. The explosive charge may be pentaerythritol tetranitrate or cyclotrimethylene trinitramine. A suitable charge for use with a No. 6 detonator consists of 1-2 grams of pentaerythritol tetranitrate or a like amount of cyclotrimethylene trinitramine.