The Ensign-bickford Company

Eric R Davis

Ernest L Gladden

Gary R Thureson

Alvaro Zappalorti

Frank J Lucca

Steven R Pellon

An isolation member (34) for use in a non-electric detonator cap (10) has an interior passageway (40) extending therethrough and defining a positioning region (44) and a discharge port (56). Positioning region (44) provides a series of interior shoulders (46), (48) and an entry shoulder (52) respectively sized to receive and seat therein signal transmission lines of different outside diameters, thereby longitudinally orienting and spacing the signal-emitting end (30a) from the receptor charge (14). The isolation member (34) is preferably made of a semi-conductive material to bleed off to the shell (12) any static electricity charges transmitted through the signal transmission line (shock tube 30) so as to prevent static discharge initiation of the receptor charge (14).

Universal isolation member and non-electric detonator cap including the

A signal transmission fuse (10, 20) such as shock tube has an outside diameter (OD) not greater than about 2.380 mm (0.0937 inch), for example, a tube outside diameter (OD) of from about 0.397 to 2.380 mm (about 0.0156 to 0.0937 inch), and the ratio of the inside diameter (ID) of the tube to the radial thickness of the tube wall (T) is from about 0.18 to 2.5. The inside diameter (ID) of the tube may be from about 0.198 to 1.321 mm (about 0.0078 to 0.0520 inch). The powder surface density of the reactive material contained within the bore (16, 30) of the fuse (10, 20) may, but need not, be significantly less than that which the prior art considers to be a minimum acceptable powder surface density. Other things, such as the cost of the material used being equal, signal transmission fuse (10, 20) of the present invention is lower in cost than conventional standard sized fuse because of its reduced diameter, and yet has good stiffness and tensile strength so as to enable it to be successfully deployed and used in the same manner as standard size signal transmission fuse.

Signal transmission fuse

An isolation member (34) for use in a non-electric detonator cap (10) is of substantially cylindrical shape and has an interior passageway (40) extending therethrough and defining a positioning region (44) and a discharge port (56). Positioning region (44) is dimensioned and configured to snugly receive and seat therein a signal transmission line (30) and to orient the signal-emitting end (30a) thereof to aim along the longitudinal axis of cap (10) through a diaphragm (42) at the target provided by receptor charge (14). The isolation member is positioned between, and spaces the signal-emitting end (30a) of the signal transmission line (30) from, the receptor charge (14) contained in the detonator cap. The isolation member comprises grooves (58, 58a, 58b) to provide an alternate flow path through which a signal emitted by the discharge end (30a) of a signal transmission line (30) can reach the receptor charge (14) should the signal fail to burst the diaphragm (42 ). The isolation member is preferably made of a semi-conductive material to bleed off to the shell (12) any static electricity charges transmitted through the signal transmission line (shock tube 30) so as to prevent static discharge initiation of the charge.

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Torrington, CT, United States of America

Eric R Davis