US2957415A - Safety device for electric primers for mines, to protect against ignition by stray electric currents - Google Patents

Safety device for electric primers for mines, to protect against ignition by stray electric currents Download PDF

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Publication number
US2957415A
US2957415A US620030A US62003056A US2957415A US 2957415 A US2957415 A US 2957415A US 620030 A US620030 A US 620030A US 62003056 A US62003056 A US 62003056A US 2957415 A US2957415 A US 2957415A
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US
United States
Prior art keywords
electric
circuit
safety device
primers
mines
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US620030A
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English (en)
Inventor
Fabrizio Lazari
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Montedison SpA
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Montedison SpA
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Filing date
Publication date
Application filed by Montedison SpA filed Critical Montedison SpA
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Publication of US2957415A publication Critical patent/US2957415A/en
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Classifications

    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C23/00—Compounds containing at least one halogen atom bound to a ring other than a six-membered aromatic ring
    • C07C23/02—Monocyclic halogenated hydrocarbons
    • C07C23/10—Monocyclic halogenated hydrocarbons with a six-membered ring
    • C07C23/12—Hexachlorocyclohexanes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2/00—Processes or devices for granulating materials, e.g. fertilisers in general; Rendering particulate materials free flowing in general, e.g. making them hydrophobic
    • B01J2/24—Obtaining flakes by scraping a solid layer from a surface
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F42—AMMUNITION; BLASTING
    • F42B—EXPLOSIVE CHARGES, e.g. FOR BLASTING, FIREWORKS, AMMUNITION
    • F42B3/00—Blasting cartridges, i.e. case and explosive
    • F42B3/10—Initiators therefor
    • F42B3/18—Safety initiators resistant to premature firing by static electricity or stray currents
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F42—AMMUNITION; BLASTING
    • F42B—EXPLOSIVE CHARGES, e.g. FOR BLASTING, FIREWORKS, AMMUNITION
    • F42B3/00—Blasting cartridges, i.e. case and explosive
    • F42B3/10—Initiators therefor
    • F42B3/18—Safety initiators resistant to premature firing by static electricity or stray currents
    • F42B3/182—Safety initiators resistant to premature firing by static electricity or stray currents having shunting means

Definitions

  • Electric primers for the ignition of blast charges or mines although offeringimportant-advantagesover-nor in the preparation of a group of bursts, in that prema- .ture and untimely detonation may be caused by stray electric currents, or by other electric phenomena that may occasionally act upon the electric circuits of the mal primers ignited by a gunpowder slow fuse, may some- -times be a source of danger. This is particularly the case usefulness, because it would require high powered generators. This would require additional insulation in the firing circuits.
  • the electric primer or igniter is coupled with a safety device which short-circuits the two electric conductors leading to the electrical firing means, the shortcircuit being located ahead of the firing means and being connected by a third conductor with the metal shell of the primer.
  • the metal shell may be grounded.
  • each primer eliminates the possibility of any potential ditference occurring between the firing circuits and the metal shell of the primer, or between the two current supply conductors. Any such potential difference could cause premature ignition of the firing circuit and hence of the primer, due either to sparking or other discharges occurring in the primer between the interior parts on different potential, or by the Ioule effect of stray current circulating through the firing circuit.
  • the safety device is built so that the short-circuit is disconnected, when desired, by remote control, after all drilled blast holes of the group to be ignited have been charged, and all circuits have been properly connected.
  • the disconnection of shortcircuits can be controlled, immediately before the firing, from the same safe location at which the firing of the blast group is initiated.
  • the disconnection by remote control of the short-circuit device can be carried out in various ways according to the present invention, for example by means of an electric current passing through a circuit independent of the one used for firing, or by pneumatic compression or by pressure release.
  • the device can take various forms and employ ditferent action mechanisms.
  • the electric current may act either by Joule effect, including the etfects of thermal expansion of elements suitable for such purpose, or by electromagnetic reflect.
  • Fig. 1 is a vertical section of a form of the short-circuiting safety device which employs an electromagnetically operated short-circuit breaking means, to normalize the igniter circuit;
  • Fig. 2 is a plan view in section on line A-A of Fig. 1;
  • Fig. 3 is a vertical section of the igniter cap or electric initiator or primer;
  • Fig. 4 is a vertical section of another form of the shortcircuiting safety device in which a fusible or low-melting substance is melted by an electric resistance wire to release a short-circuit breaking means, whereby the igniter circuit is normalized;
  • Fig. 5 is a vertical section of a third form of safety device in which pneumatic means is employed to open the short circuit.
  • the structure of the electric initiator, primer or igniter cap may be of any conventional design.
  • the electric conductors 8 of the firing circuit are connected at couplers 23 (Fig. 3) to connector wires 8' which lead into a casing or package 1.
  • This casing contains the usual igniting bridge resistance wire surrounded by an ignition composition (not shown).
  • a priming charge 1' About the lower end of easing 1 is a priming charge 1', and below the latter is a pressed base charge 24.
  • the outer primer casing 20 is generally a bronze shell the upper part of which is sealed by a rubber or plastic seal 21.
  • Electro-conductively connected to metal shell 20 is a conductor wire 9 the upper end of which passes through insulator sealing plug 6 in the lower end of the metal casing 7 of the safety device.
  • Wire 9 is electroconduetively connected at its upper end to one of the three bent conducting strips 4. These strips 4 are supported upon insulating material 5.
  • One of the functions of wire 9 is to ground a strip 4 through metal casing 20.
  • the two covered conductors 8 pass through lower and upper plugs 6, each conductor 8 being eleetro-conductively connected to one of the remaining two strips 4.
  • the leads 3a are connected to energize the electromagnet 3, which controls an armature 3' fixed upon the lower end of a reciprocable,
  • metallic clectro-conductive piston 2 This piston has a flared head which electro-conduc-tively bridges the three strips 4 as shown in Fig. 2.
  • At 7a is an insulating sleeve. Normally the piston 2 is held in its lowermost position by 3 compression spring 2', and thus serves to short-circuit the two conductors 8; that is, to connect them to each other and to connect them to casing 20, and to ground when the latter is placed in a bore hole.
  • the electromagnet which isin an electric circuit independent of the firing circuit, causes the movement-of piston or core 2, and this movement, by disconnecting the pre-existing short-circuit, reestablishes the normal electric circuit for igniting the electric firing means.
  • the safety device comprises a metal casing 47 sealed at its upper and lower ends-by means of insulator plugs 46 through which pass the covered leads 48.
  • each of the conductors-48 is connected to a bent metal strip 44 of which there ar e three, all disposed like strips 4 of Figs. 1 and 2.
  • the strips are supported on or embedded in insulating material 52.
  • a conductor 19, which serves the samegpurpose as conductor 9 of Fig. 1, is connected to the third strip 44 and-to-the'primer-casing 20.
  • the three strips are electrically connected to each other by the central bridging disc or metal flange 48' fixed upon the upper end of reciprocable piston '50. The latter is under upward pressure of compression spring 49'.
  • Piston '50 ordinarily cannot move upwardly because it is immovably held in its lowermost position by a dielectric mass 53 melting at 50-200 C., such as sul- .fur.
  • a dielectric mass 53 melting at 50-200 C. such as sul- .fur.
  • the apparatus can also be operated by applying suction, by disposing flange 62' below the ends of the contacrstrips 64, why "reversing the positions of the diaphragm 63.
  • paratus including electric circuit means to initiate a blas apparatus is grounded.
  • conductive circuit means normally connecting the two cuit comprising an electromagnetic coil operatively posi- Immediately before the burst, a suitable air pressure of vacuum is applied which causes displacement of the pistons whereby the pre-existing short-circuit is cut oil. This reestablishes the normal electric circuit ⁇ or the ignition o the electrical firing means.
  • An electric blasting initiator comprising igniter a the said electric circuit means having two conductors co nected thereto and adapted to be connected to an electrit, current source and to carry current to and from the igniterapparatus, a separate safety device comprising electro conductive means normally connecting the two conductors to short circuit themlahead of the igniter electric circui' means, and remotely controllable means independent the blast'initiating circuit to disconnect the electro-conductive means at the will of the operator, to remove the short-circuit preparatory to initiating the blast, the independent means comprising an electromagnetic coil, the position of the electro-conductive means being controlled by the electromagnetic coil, said electro-conductive means normally grounding the two conductors when the igniter 2.
  • An electric blasting initiator comprising igniter apparatus including an electro-conductive outer shell and electric circuit means to initiate a blast, said electric circuit means having two conductor leads connected thereto adapted to be connected to an electric current source and to carry current to and from the igniter apparatus from a distance, a separate safety device comprising electroconduetors to short circuit them and normally connecting them to the said outer shell, and remotely controllable means to open circuit the electro-conductive circuit means at the will of the operator, to remove the short-circuit preparatory to initiating the blast, the means to open cirtioned to control a movable part of said elcctro-conductive circuit means, said electro-conductive means normally grounding the two conductors when the igniter apparatus is grounded.
  • the electro-conductive circuit means of the safety device comprising two conductive elements each connected to one of the two conductor leads, and further comprising a third conductive element connected to the outer shell of the igniter, and further comprising a moveable piston having at least a part thereof normally in position to electrically connect the three conductive elements, the electromagnetic coil controlling the position of the piston.

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Air Bags (AREA)
  • Fuses (AREA)
  • Automotive Seat Belt Assembly (AREA)
US620030A 1955-11-10 1956-11-02 Safety device for electric primers for mines, to protect against ignition by stray electric currents Expired - Lifetime US2957415A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
IT339851X 1955-11-10

Publications (1)

Publication Number Publication Date
US2957415A true US2957415A (en) 1960-10-25

Family

ID=11238478

Family Applications (1)

Application Number Title Priority Date Filing Date
US620030A Expired - Lifetime US2957415A (en) 1955-11-10 1956-11-02 Safety device for electric primers for mines, to protect against ignition by stray electric currents

Country Status (6)

Country Link
US (1) US2957415A (de)
BE (1) BE552499A (de)
CH (2) CH339851A (de)
DE (1) DE1022140B (de)
FR (2) FR1166112A (de)
GB (2) GB842043A (de)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3075461A (en) * 1960-10-28 1963-01-29 Bilker & Moyerman Method and apparatus for detonating radio frequency sensitive blasting caps
US3094932A (en) * 1960-07-15 1963-06-25 William D Greenlees Electromagnetic radiation proof igniting device
US3308758A (en) * 1964-07-02 1967-03-14 Dynamit Nobel Ag Ignition device
US3414292A (en) * 1966-07-01 1968-12-03 Eaton Yale & Towne Inflatable safety device
US3457431A (en) * 1968-02-20 1969-07-22 Dow Chemical Co Time-delayed control device
US3585933A (en) * 1969-05-02 1971-06-22 Us Army Detonator safety device
US5129322A (en) * 1990-05-14 1992-07-14 Jet Research Center, Inc. Explosive tubing cutter and method of assembly

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
IL74188A0 (en) * 1985-01-29 1985-04-30 State Of Israel Ministriy Of D Pyrotechnic grenade
US4869171A (en) * 1985-06-28 1989-09-26 D J Moorhouse And S T Deeley Detonator

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1726053A (en) * 1927-10-10 1929-08-27 Brown Ladura Alexander Safety coupler
GB375536A (en) * 1930-07-23 1932-06-30 Lignoza Spolka Akcyjna Improvements in or relating to the circuit of electric blasting fuses
US2026962A (en) * 1934-03-01 1936-01-07 George D Brown Safety switch
US2494256A (en) * 1945-09-11 1950-01-10 Gulf Research Development Co Apparatus for perforating well casings and well walls
GB677824A (en) * 1949-01-22 1952-08-20 Schlumberger Prospection Improvements in devices containing hollow explosive charges for perforating or cutting bore-hole linings or casings
US2632389A (en) * 1949-09-13 1953-03-24 Atlas Powder Co Electric explosion initiator
US2704032A (en) * 1951-01-30 1955-03-15 Maruschak Nick Safety mine shooting devices

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1726053A (en) * 1927-10-10 1929-08-27 Brown Ladura Alexander Safety coupler
GB375536A (en) * 1930-07-23 1932-06-30 Lignoza Spolka Akcyjna Improvements in or relating to the circuit of electric blasting fuses
US2026962A (en) * 1934-03-01 1936-01-07 George D Brown Safety switch
US2494256A (en) * 1945-09-11 1950-01-10 Gulf Research Development Co Apparatus for perforating well casings and well walls
GB677824A (en) * 1949-01-22 1952-08-20 Schlumberger Prospection Improvements in devices containing hollow explosive charges for perforating or cutting bore-hole linings or casings
US2632389A (en) * 1949-09-13 1953-03-24 Atlas Powder Co Electric explosion initiator
US2704032A (en) * 1951-01-30 1955-03-15 Maruschak Nick Safety mine shooting devices

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3094932A (en) * 1960-07-15 1963-06-25 William D Greenlees Electromagnetic radiation proof igniting device
US3075461A (en) * 1960-10-28 1963-01-29 Bilker & Moyerman Method and apparatus for detonating radio frequency sensitive blasting caps
US3308758A (en) * 1964-07-02 1967-03-14 Dynamit Nobel Ag Ignition device
US3414292A (en) * 1966-07-01 1968-12-03 Eaton Yale & Towne Inflatable safety device
US3457431A (en) * 1968-02-20 1969-07-22 Dow Chemical Co Time-delayed control device
US3585933A (en) * 1969-05-02 1971-06-22 Us Army Detonator safety device
US5129322A (en) * 1990-05-14 1992-07-14 Jet Research Center, Inc. Explosive tubing cutter and method of assembly

Also Published As

Publication number Publication date
GB874332A (en) 1961-08-02
FR74069E (fr) 1960-11-07
DE1022140B (de) 1958-01-02
CH350234A (fr) 1960-11-15
FR1166112A (fr) 1958-11-03
BE552499A (fr) 1956-11-30
CH339851A (fr) 1959-07-15
GB842043A (en) 1960-07-20

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