GB868279A - Improvements in seismic prospecting devices - Google Patents

Abstract

868,279. Explosive assemblies for geophysical prospecting. DU PONT DE NEMOURS & CO., E. I. March 7, 1960 [March 6, 1959], No. 8027/60. Class 9(1). A delay element and connecting device for propagating explosion comprises at least two rigid elongated telescopic tubes 7, 8, means 17, 18 at each end of the said assembly for connecting an explosive charge or another delay unit thereto, and a delay producing unit 11 within the said assembly, comprising an explosive element extending from one connecting means to the other and being at least as long as the fully extended assembly. The delay unit consists of low energy connecting cord comprising a core of detonating explosive, an inner metal sheath, preferably lead or a tinlead alloy, and a protective waterproof outer sheath of e.g. rubber or polyethylene. At the ends of the connecting cord are tubular shells 12, containing an initiating explosive charge e.g. PETN and secured by crimps 13. A primary charge 16 e.g. PETN, RDX, is inserted in a plug 15a sealing the free end of the tube 8. The detonating explosive may be either nitromannite, HMX, lead azide, picryl sulphone, the lead salt of dinitro-ocresol, or a mixture of 50 parts of smokeless powder, 25 parts of the lead salt of dinitro-ocresol, and 25 parts of potassium perchlorate. Specification 857,178 is referred to.