NON-ELECTRIC DOUBLE DELAY BOREHOLE DOWNLINE UNIT FOR BLASTING OPERATIONS

摘要

1535558 Blasting NITRO NOBEL AB 9 Feb 1976 [10 Feb 1975] 5028/76 Heading E1F [Also in Division F3] A delay device for sequentially firing explosive charges 30, 32', 32" contained in a series of boreholes, comprises a flexible tube 12 for propagating an explosive signal both to a delay detonator 14 attached to one end of the tube and to a delay transmission cap 16 connected to the other end of the tube and housed in a connecting block 18 which, in use, contains a looped intermediate portion of a tube 12 of a second device for transmitting the explosive signal thereto. The ratio of the delay period of the blasting cap and the transmission cap being at least 2:1 and extending up to 50:1. The interior wall of the tube 12 may be coated with an explosive having core load less than 0.5 grams per metre, and preferably less than 0.1 grams per metre. The base of the amplifying cap contains an explosively inert material 50 to promote a side initiating function. The connecting block is provided with a lug 70 and a flange 27 around which the tube 12 of another delay device can be looped. In use, the explosive signal is introduced into the tube 12 of a first device by means of a detonating cord 76 tied thereto, and thesignal travels in opposite directions along each arm of the loop towards the caps 14 and 16. The cap 16 transmits the signal to the tube 12 of the next delay device before the cap 14 fires the charge 30.