US2773447A - Ventless delay electric initiators - Google Patents

Ventless delay electric initiators Download PDF

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Publication number
US2773447A
US2773447A US337622A US33762253A US2773447A US 2773447 A US2773447 A US 2773447A US 337622 A US337622 A US 337622A US 33762253 A US33762253 A US 33762253A US 2773447 A US2773447 A US 2773447A
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United States
Prior art keywords
delay
ventless
lead
composition
charge
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Expired - Lifetime
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US337622A
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English (en)
Inventor
Cecil R L Hall
Idwal O Lewis
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Imperial Chemical Industries Ltd
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Imperial Chemical Industries Ltd
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Publication date
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Publication of US2773447A publication Critical patent/US2773447A/en
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    • 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
    • F42B3/16—Pyrotechnic delay initiators

Definitions

  • the present invention is concerned with improvements in or relating to delay electric initiators and is particularly concerned with ventless short delay electric detonators.
  • the delay elements in ventless short delay electric detonators have usually comprised a length of rigid metal tubing into which a powdered delay composition that yields little or no gas or vapour as it is consumed has been introduced in increments each of which is highly compressed into said length of tubing before the next increment has been introduced.
  • this incremental loading is considered essential in order to give the composition the required mechanical strength and to ensure that the packing is of a uniform density along the whole length of the column so that a rigid tube of a given length loaded with the same fuse composition will always give the same delay period.
  • Ventless short delay electric detonators are also produced in which the delay element is produced by filling a lead tube with a delay composition, for example, a mixture of silicon and red lead, rolling or swaging the tube to a suitable diameter to give a good fit in the ventless container and cutting off the length required.
  • a delay composition for example, a mixture of silicon and red lead
  • ventless short delay electric detonators when adapted to give short delay intervals, for example, of the order of 25 or 50 milliseconds have a tendency to cause ignition of an inflammable gas mixture, for example, 9% methane/air mixture, when fired freely suspended therein.
  • the object of the present invention is to provide a series of ventless short delay electric detonators having delay intervals between successive delay numbers, for example, of the order of 25 or 50 milliseconds which, when the ventless container consists at least essentially of copper, have the advantage that single detonators of any such practical series when fired freely suspended in an inflame mable gas mixture, for example, 9% methane/air mix' It was recognised that if it were possible it would be ⁇ cheaper to make ventless short delay electric detonators having a short delay composition enclosed in a lead tube,
  • ventless container were to consist at least essentially of copper.
  • ventless short delay electric detonators suitable for short delay firing can in fact be produced much more economically than those previously known by using as the delay element a length cut off from a fuse comprising a delay fuse composition enclosed in a lead sheath of such thickness that it is consumed or melts 2,773, 14? Patented Dec. 11, 1956 at substantially the same rate as that at which the flame front advances along the delay element on reaction of its delay composition and a covering for said lead sheath of a thickness which will give the delay element a total thickness substantially equal to the internal diameter of the ventless container.
  • ventless short delay electric detonators have the additional advantage of not causing ignition of inflammable gas mixtures, for example a 9% methane/ air mixture, when fired freely suspended therein if the ventless containeris of copper or a copper alloy.
  • the ventless shortdelay electric detonator comprising an. electrically actuated igniting charge, an initiating charge and an interposed short delay element enclosed in a ventless container
  • the sheath of said short delay element is of lead of such thinness as to be consumed or melted at substantially the same rate as that at which the flame front advances along the delay element on reaction of its delay composition and in that the sheath has a covering of a thickness to occupy the space between said sheath and container.
  • the ventless container consists essentially of copper or of a copper alloy rich in copper.
  • the covering is friable and permeable to the.
  • gasless delay composition may consist for:
  • the delay fuse composition for the core may consist of a conventional fast burning fuse composition for example a mixture of silicon and red lead in amount from 5 to 35% by weight of silicon and from to 65% by weight of red lead.
  • gasless delay compositions produce a little gas on reaction and when these are used in a conventional manner in a lead sheath which has comparatively thick walls which are not melted or consumed until some time after the flame front has passed, the pressure developed by the gaseous products of reaction is sufiicient to cause the hot slag remaining after reaction to be ejected forcibly as soon as the ventless container is disrupted. Any tendency for the hot slag to be forcibly ejected is substantially removed in the ventless short delay electric detonators of the present invention.
  • the lead sheath is preferably of a thickness less than the diameter of the core of the short delay element, for
  • the core may be 0.050 inch in diameter and the lead sheath may be 0.015 inch thick, whereas in the conventional lead fuse delay element the diameter of the fuse an internal diameter of 0.050 inch.
  • the thin lead fuse thus produced is then covered so as to bring it to a size to fit the ventless container by for example wrapping it with paper or by spinning textiles around it and applying i a finish of, for instance, a thermoplastic resin.
  • the delay element in posi-' tion by pressing an inverted perforated metal cup over the end thereof remote from the initiating composition instead of relying on a friction fit between the delayfelement and the wall of the ventless container.
  • the useof such a cup also prevents the covering, if ignitible, from being. ignited by the igniting charge.
  • the delay element of the ventless short delay electric detonator of the invention can be readily inserted into i y the container without the application of so high a pressure as to damage the structure of the delay'ele'ment'because the soft and somewhat compressible nature of the covering permits thenecessary tight fit to 'beieasily attained.
  • Anexpansionspace should be left between the end of the delay element and the igniting charge.
  • a small charge of supplementary, preterably'ga'sless, igniting composition may be interposed'between the end of thedelay element'and the initiating charge. It is also. sometimesdesirable to press a small charge of gasless igniting composition directly on top of the delay element, for example, by pressing itinto the pr'forated metal clip prior to assembly in order to ensure the ignition "of the delay composition from the electrically actu ated igniting charge which is 'usually spaced from the delay 'element.
  • the electrically actuated'igniting charge maybe an electric fus'ehead.
  • 8 and '9 are layers of gasless igniting compositionconsisting'ot silicona'nd red lead in the'weight ratio 30 to 70
  • 10 isan inverted perforated metal cup pressed over the compositio'n 9 andover the top of the delay element so as to secure, it longitudinally in the'tube and eifectively seal off the space above this cup from the composition 9, 1 1, is an electric fusehead
  • 12 is an axially perforated sealing plug of rubber-like material crimped between the copper tube 1 and the insulated electric'leadingfwires 13 and13 asshown at 14 whereby there 'is attainedfa seal capable of withstanding an'internalpressure greater than the maximum pressure that can beproduced as a result of the combustion of the contents of the "detonato'r tube with the exception of the detonating explosive charges 2 and 3.
  • the space ISJbetwe'en the I end 'of the plug 12' and the'inverted cup 10 is sufiicient to ensure that the maximumpressure that can even temporari lybe'developedin the initiator by'the successive consumption of the compositions of the electric fusehead 11,
  • the igniting charge 9 the composition 7 of the delay element, t'o'getherwith any gases which may arise from char- -ring of its'cov ei'ings, and the igniting charge 8 will not 7 unseal thetube.
  • The. invention is also illustrated by the followingex amples'inwhich allpercentages are by weight.
  • the lead delay elements in Examples 1 to 7 have "an I externaldiameter of 0.08" and internal diameter of'0.05
  • Examples 8 and 9 are the 'same as those of Examples 1 to 7 except that the 'lead'fu'se instead of having a paper covering has a spun jute covering and an outer coat of polythene.
  • a ve'ntless short delay electric detonator comprising an electrically actuated igniting charge, 'an initiating charge and an interposed short delay element comprising a core of red leadand silicon and a lead'sheath of a thickness less than the diameter ofthe core enclosed in a "ventless container consisting essentially of copper,
  • thelead sheath :of said short delay element is of such thinriss as to be melted at substantially the same rate asthat at which r, the flame front advances along the delay element on reaction of its core of delay composition 7 and wherein the said sheath has agas-permeable textile covering of afthickness to occupy the space between the said sheath and ventless container.
  • I I v 2 A ventles s short delay electricdetonator as claimed claim 1 wherein the core is 0.050 inch in diameter and the lead sheathis 0.015'lI1Ch thick.

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Air Bags (AREA)
US337622A 1952-04-21 1953-02-18 Ventless delay electric initiators Expired - Lifetime US2773447A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB9935/52A GB716909A (en) 1952-04-21 1952-04-21 Improvements in or relating to ventless delay electric initiators

Publications (1)

Publication Number Publication Date
US2773447A true US2773447A (en) 1956-12-11

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US337622A Expired - Lifetime US2773447A (en) 1952-04-21 1953-02-18 Ventless delay electric initiators

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US (1) US2773447A (fr)
BE (1) BE519351A (fr)
DE (1) DE942319C (fr)
FR (1) FR1075552A (fr)
GB (1) GB716909A (fr)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2953214A (en) * 1957-02-27 1960-09-20 Shell Oil Co Seismic exploration
US3009418A (en) * 1959-04-24 1961-11-21 Hercules Powder Co Ltd Firing device
US3041914A (en) * 1958-02-19 1962-07-03 Ici Ltd Delay fuse elements for delay electric detonators and delay electric detonators containing them
US3046889A (en) * 1957-02-27 1962-07-31 Shell Oil Co Seismic exploration
US4369708A (en) * 1979-09-21 1983-01-25 E. I. Du Pont De Nemours And Company Delay blasting cap
US4429632A (en) 1981-04-27 1984-02-07 E. I. Du Pont De Nemours & Co. Delay detonator
CN103033101A (zh) * 2012-12-27 2013-04-10 雅化集团绵阳实业有限公司 一种新型长秒量延期电雷管及其生产工艺

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1076542B (de) * 1955-08-03 1960-02-25 Canadian Ind Verzoegerungszuendsatz
DE1137354B (de) * 1959-10-29 1962-09-27 Oregon Ets Patentverwertung Verzoegerungshuelse zur Aufnahme eines Verzoegerungssatzes fuer Schlagzuender fuer Granaten, vorzugsweise Handgranaten

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1825224A (en) * 1930-02-28 1931-09-29 Ensignbickford Co Safety fuse
US1999820A (en) * 1931-06-24 1935-04-30 Hercules Powder Co Ltd Delay cap
US2207137A (en) * 1939-01-24 1940-07-09 California Cap Company Electric blasting cap
US2478415A (en) * 1948-05-22 1949-08-09 Du Pont Blasting initiator
US2586959A (en) * 1949-09-16 1952-02-26 Canadian Ind Delay electric blasting cap
US2619035A (en) * 1947-12-31 1952-11-25 Ici Ltd Production of ventless delay initiators for explosive or other charges capable of exothermic reaction

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR354364A (fr) * 1905-04-21 1905-10-04 Societe Fabrik Elektrischer Zuender G. M. B. H. Amorce électrique à action retardée
US2103432A (en) * 1935-08-27 1937-12-28 Hercules Powder Co Ltd Electrical firing device
GB462000A (en) * 1935-08-29 1937-03-01 Charles Edwin Sosson Improvements in or relating to delay action detonators and fuzes and delay compositions for use therein

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1825224A (en) * 1930-02-28 1931-09-29 Ensignbickford Co Safety fuse
US1999820A (en) * 1931-06-24 1935-04-30 Hercules Powder Co Ltd Delay cap
US2207137A (en) * 1939-01-24 1940-07-09 California Cap Company Electric blasting cap
US2619035A (en) * 1947-12-31 1952-11-25 Ici Ltd Production of ventless delay initiators for explosive or other charges capable of exothermic reaction
US2478415A (en) * 1948-05-22 1949-08-09 Du Pont Blasting initiator
US2586959A (en) * 1949-09-16 1952-02-26 Canadian Ind Delay electric blasting cap

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2953214A (en) * 1957-02-27 1960-09-20 Shell Oil Co Seismic exploration
US3046889A (en) * 1957-02-27 1962-07-31 Shell Oil Co Seismic exploration
US3041914A (en) * 1958-02-19 1962-07-03 Ici Ltd Delay fuse elements for delay electric detonators and delay electric detonators containing them
US3009418A (en) * 1959-04-24 1961-11-21 Hercules Powder Co Ltd Firing device
US4369708A (en) * 1979-09-21 1983-01-25 E. I. Du Pont De Nemours And Company Delay blasting cap
US4429632A (en) 1981-04-27 1984-02-07 E. I. Du Pont De Nemours & Co. Delay detonator
CN103033101A (zh) * 2012-12-27 2013-04-10 雅化集团绵阳实业有限公司 一种新型长秒量延期电雷管及其生产工艺
CN103033101B (zh) * 2012-12-27 2015-06-17 雅化集团绵阳实业有限公司 一种新型长秒量延期电雷管及其生产工艺

Also Published As

Publication number Publication date
FR1075552A (fr) 1954-10-18
GB716909A (en) 1954-10-20
BE519351A (fr)
DE942319C (de) 1956-05-03

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