GB577873A - Improvements in or relating to delay action initiators for explosive charges - Google Patents

Abstract

577,873. Blasting detonators. JONES, E., and IMPERIAL CHEMICAL INDUSTRIES, Ltd. Feb. 15, 1943, No. 2456. [Class 9 (i)] A waterproof delay-action friction initiator, particularly for explosive demolition charges, has a disengageable hand - actuated member, which, in its fixed position, covers venting apertures and forms part of the waterproof enclosure, and has associated with it pull-actuated friction means for initiating combustion after opening the vent or vents. In one form as shown in Figs. 1, 2 and 6 of the Provisional Specification, the delayaction charge 7 contained in a tube 5 is held in a detonator tube 1 by a paper tube 4, and to the upper end of the tube 1 is fixed a metal tube 9 having nibs 11 and venting apertures 10. Fitting over the tube 9 is a hand-actuated member 16 which is provided with bayonetslots 17 to coact with the nibs 11, and which normally covers the venting apertures 10 is taped at its lower end to the tube 9 to prevent access of moisture to the interior. A wire 18 has one end secured to the member 16 and its inner end is formed as a stiff helix 14 adapted to contact with the lower end of a distancesleeve 15, the upper end of which abuts against a cup 12 charged with an ignition pellet 13, the cup and tube being perforated at their ends to provide passage for the wire 18 so that it can be secured at 22 to the member 16. A guard 23 is provided to prevent burning of the hands of the operator after the vents are opened. For firing, the member 16 is rotated and pulled, so that the vents 10 are opened and the distorted wire 14 contacts the pellet 13 and fires the delay-action charge 7 without risk to the operator. A further delay extension-tube may be fitted to the main detonator container and in this case, further vent-holes may be provided in this tube between the adjacent ends of the delay-action charges. In a modification shown in Fig. 2 of the Complete Specification, the wire is formed in two helices 14, 40 within a cap member 54, and the end of the wire is attached to a screw plug 56 provided with a handle 59, the vent in this case being provided by the aperture 55<1> receiving the plug which has first to be unscrewed before it can be pulled away from the main device, thus opening the vents and causing ignition of the pellet 13.