Electric detonator ignition systems

Claim 1

AN ELECTRIC BLASTING CAP RESISTANT TO STATIC DISCHARGES AND STRAY CURRENTS COMPRISING AN ELONGATED TUBULAR METAL SHELL, A BASE CHARGE OF DETONATING EXPLOSIVE AT THE BOTTOM OF SAID SHELL, AN INITIATION CHARGE SUPER-IMPOSED DIRECTLY ON SAID BASE CHARGE, AN IGNITION CHARGE SUPER-IMPOSED DIRECTLY ON SAID INITIATION CHARGE, A BRIDGEWIRE CONNECTED TO THE ENDS OF A PAIR OF LEG WIRES IMBEDDED IN SAID IGNITION CHARGE, A BRIDGE PLUG OF INSULATED MATERIAL SURROUNDING AND SUPPORTING SAID LEG WIRES, THE BASE OF SAID PLUG BEING SUPER-IMPOSED DIRECTLY ON SAID IGNITION CHARGE, A LAYER OF POROUS DIELECTRIC MATERIAL SURROUNDING SAID LEG WIRES AND BEING SUPER-IMPOSED DIRECTLY ON SAID PLUG, A LAYER OF WATER-PROOF SEALING MATERIAL SURROUNDING SAID LEG WIRES AND BEING SUPER-IMPOSED DIRECTLY ON SAID LAYER OF POROUS DIELECTRIC MATERIAL; THE LOWER PORTION OF SAID PLUG HAVING A SMALLER CIRCUMFERENCE THAN THE UPPER PORTION THEREOF, A SECTION OF DIELECTRIC TUBING FITTED OVER SAID LOWER PORTION OF SAID PLUG SO AS TO FILL THE ANNULAR SPACE BETWEEN THE LOWER PORTION OF SAID PLUG AND SAID SHELL WALL, SAID TUBING BEING OF A LENGTH SUCH THAT ITS LOWER PORTION EXTENDS DOWNWARD AROUND A PORTION OF THE IGNITION CHARGE AND BELOW THE LEVEL OF THE BRIDGEWIRE SO AS TO PROVIDE A LONGER POTENTIAL ARC PATH BETWEEN THE ENDS OF SAID LEG WIRES AND SAID SHELL THAN THE POTENTIAL ARC PATH BETWEEN THE LEAD WIRES AND SAID SHELL THROUGH SAID POROUS DIELECTRIC LAYER, SAID IGNITION CHARGE BEING A COMPOSITION SELECTED FROM THE GROUP CONSISTING OF (A) A MIXTURE COMPOSED OF FROM 1. 5 TO 2.5%, BY WEIGHT, OF AMORPHOUS BORON AND FROM 98.5 TO 97.5% BY WEIGHT, OF PBO; (B) A MIXTURE COMPOSED OF FROM 8 TO 30%, BY WEIGHT, OF AMORPHOUS BORON AND FROM 92 TO 70%, BY WEIGHT, OF PBO AND; (C) A MIXTURE COMPOSED OF 15 TO 30%, BY WEIGHT OF AMORPHOUS BORON AND ROM 85 TO 70%, BY WEIGHT, OF PB3O4; SAID COMPOSITION BEING IN GRANULAR, FREE-FLOWING FORM AND HAVING A BULK DENSITY OF FROM 1.2 TO 3 GRAMS PER CC.