GB693795A - Improvements in or relating to detonator shields - Google Patents

Abstract

693,795. Blasting detonators. IMPERIAL CHEMICAL INDUSTRIES, Ltd. Feb. 11, 1952 [June 8, 1951], No. 13613/51. Class 9(i) A shield 1 to position an electric detonator in an explosive charge and to protect it from accidental initiation has an upper body portion 2 and a lower threaded portion 3 of reduced diameter. Formed in the shield is a through passage 4 for a detonator and extending from the passage 4 across the concave top 6 of the shield is a slot 5 continued diagonally across the shield to the lower end of the passage 4. The upper part of the slot is sufficiently wide and deep to accommodate two insulated leading wires, while the lower part of the slot will hold from leading wires without any of the wires projecting beyond the contour of the shield. The shield is screwed into a recessed portion 8 of a primer canister provided with a detonator-receiving tube 9. The opposite end of the canister has an externally threaded projection 10 adapted to engage a recessed threaded portion 11 of a canister 12 containing blasting explosive. Several canisters 12 may be screwed together to form a column of explosive. With larger charges the shield may be screwed into an adapter similar to the recessed part 8, a detonator tube being screwed into the adapter. To use the shield an electric detonator is passed upwards through the hole 4 taking part of the lead wires with it. The wires are then pressed into the slot 5 and their free ends brought upwards along the diagonal part of the slot while the detonator is inserted in the tube 9 and the shield is screwed into the recess 8. The shield is preferably of non-metallic and non-electrically conducting material, e.g. wood, hard rubber or synthetic resins.