BLASTING CIRCUIT (EN: blasting circuit; DE: Zundleitung, Zundkreis; FR: circuit de tir; ES: circuito de tiro; RU: взрывная сеть) is the combination of the means for the blasting, and of the special connecting elements (electric wires, detonating cord, and so on), which are connecting the means for the blasting each with others, and with the external source of the energy (electrical, thermal, and so on), which is necessary for the excitation of the initial pulse, and for the subsequent explosion of the charge.
Depending on the method for the blasting, they distinguish the electric-explosive circuit, the electric-firing circuit, and the circuit, which is made of the detonating cord.
The electric-explosive circuit (serial, parallel, and mixed, see the Figure # 1) comprises the trunk electric wire, which is connecting the source of the electric current with the distribution network, through which the current is being distributed among the electric detonators.
The terminal wires, which are going from the outgoing wires of the electric detonator, and the local wires, which connect the terminal wires of the electric detonators among them, and attach them to the trunk wire, form the distribution network. For the improvement of the reliability, in case of the especially important explosions, they use the double-redundant blasting circuits. For the construction of the electric-explosive circuits, they use the wires, which are specially purposed for the blasting works, and also the insulated wires for the installations.
The electric-firing circuit comprises the terminal segments of the fire-conducting cord, the igniting tubes, the electric igniters, which are connected with these tubes, and the electric wires, through which there is supplied the electric current from the external source. They sometimes connect the terminal segments of the fire-conducting cord within the igniting cartridge, in this case the ignition is performed using one igniting cartridge simultaneously.
The blasting circuit, which is made of the detonating cord (see the Figure # 2), comprises the trunk detonating cord (or several cords), which is connecting the source of the detonation with the distribution network, through which the detonation is transmitted through the terminal segments of the detonating cord to the live charge (live primer).
They perform the initiation of the circuit, which is made of the detonating cords, using the igniting tube or the electric detonator, which is attached to the trunk detonating cord. In those cases, when there is necessary to explode the charges or the groups of the charges at the different times with the millisecond delays, they install before this group of the charges the retarders, namely, the pyrotechnic relay.
There is widespread the blasting circuit, which is made of the detonating cord (especially at the opencast works), which is the most simple, reliable, and safe. Within the USSR, the installation and activation of the blasting circuit are conducted in accordance with the "Unified rules for the safety during the blasting works".
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