US2195032A - Detonator - Google Patents

Description

Patented Mar. 26, 1940 srras PATENT oFFIcE Pa., assignors to Atlas Powder Company, Wilmington, lDel., a corporation of Delaware No Bra. Application April 16, 1938, Serial No. 202,437

Claims.

Our invention relates to improvements in detonators, such as are used for initiating charges of explosives. It is applicable to both electric and safety fuse types of both simple and compound detonators.

More specifically, it pertains to improved ignition media. for detonators, whose main charge orcharges (primary as well as base charges) are of the so-called safety types or defined as being free of any explosive ingredient which is as sensitive to friction and impact as any of the group of explosives exemplified by mercury fulminate, lead azide, diazodinitrophenol, and the like. Detonators of this type have previously been proposed, as for example in U. S. Patents 1,928,204

' to 1,928,208 to Large, which patents also show that unusual and specific types of ignition media are requisite.

All previously proposed ignition media for these types of detonators have one or more objectionable features, however, over which the products of the present invention have certain advantages. Whereas pre-formed fuse-heads functionquite satisfactorily (see U. S. Patent 1,928,205 to Large), they have the objection of being less simple in construction than ignition media in the form of superimposed layers or wafers of inflammable compositions, functioning to transmit ignition from either safety-fuse or electrically heated bridge-wires to the safety type of primary detonator composition. On'the other hand, flash compositions, heretofore proposed for use in the latter form of ignition medium, also have one or more objections. Some are insufliciently moisture resistant to be of practical use for open type fuse-caps, some are so hot or violent that they melt or otherwise prematurely injure the confining means of a safety type primary detonator charge so as to render it unreliable, some are required in uneconomically large amounts, while some are relatively dangerous to manufacture on account of their high sensitivity to friction. One of the chief difficulties has been to find a flash composition that is relatively safe to manufacture, is sufliciently moisture resistant and otherwise suitable for use in open type fusecaps, and which, at the same time, can be used in economically small amounts.

An object of the invention is the production of\ new and improved types of detonators overcoming these difliculties and objections. V Another object of the invention is the production of detonators characterized by excellent and reliable detonating efficiency, by low cost, andby being relatively safe for manufacture and use.

- onators comprising A still further object of the invention is the production of an improved ignition medium. for a safety type primary detonator composition.

Other objects of the invention will hereinafter more fully appear. 5

This application is a continuation-in-part of our co-pending application Serial No. 63,396 filed February 11, 1936.

The present invention consists in the employment of inflammable compositions comprising diazodinitrophenol (4 -6 dinitro-2 diazophenol) as the ignition or kindling media for the safety type of primary detonator composition in a detonator. This invention is based on our discovery that diazodinitrophenol functions, in very small quantities, as ignition media for the inflammation or kindling of safety" types of primary detonator charges, such as nitromannite, nitrodulcite, nitrolactose and the like; diazcdinitrophenol being at the same time appreciably more moisture resistant for use in open-type fuse caps and somewhat safer to manufacture than previously proposed compositions that are usable for this purpose, in such small quantities.

This is in contradistinction to the characteristics of mercury-fulminate and certain admixtures thereof, which are unsuitable for this purpose, as pointed out on page 2, lines 76-114 of U. S.'Patent 1,928,208 to Large. .Although diazodinitrophenol and mercury fulminate are considered equivalent for use in conventional types of detthem, in that they are simflaiin respect to their both being capable of quickly advancing from ignition to detonation (particularly when confined), they have been found to differ widely in their actions as ignition media for the inflammation of "safety types of primary detonator compositions. Whereas we have found diazodinltrophenol to function in very small quantities (as little as .01 gram) 40 to effectively ignite the confined safety" type of primary charge, as nitromannite and the like, without premature injury to the confining means (as the shell and/or inner capsule surrounding the said primary charge); fulminate of mer- 45 cury, in similar amounts, merely destroys the confinement without effectively igniting the safety type of primary charge.

While we are aware that diazodinitrophenol has been proposed heretofore as a detonating explosive charge in various types of detonators, as for example as the essential ingredient of primary as well as secondary charges in compound detonators, percussion' caps, etc., we nevertheless believe ourselves to be the first to propose a detonator comprising a. "safety" type of primary detonator charge capable of ignition by adeflagrating, non-detonating medium and of advancing from deflagration' to detonation, and for the ignition of said primary charge, an ignition medium comprising diazodinitrophenol, said ignition medium serving to fire the primary charge by initiating deflagration therein as distinguished from initial detonation therein. By

. firing the primary charge by initiating deflagration therein as distinguished from initial detonation therein is meant the firing of the primary charge by an ignition medium incapable of detonating a non-primary base charge which will not advance from inflammation to detonation such as tetryl, but capable of igniting a confined "safety type primary charge with sumcient inflammation so that the confined primary charge will advance from ignition to detonation.

A marked distinction must be drawn between the functioning of diazodinitrophenol as an inflammatory ignition medium for kindling the "safety type of primary detonator charge and its functioning as a primary charge, itself, in compound detonators, as described, for example, in U. S. Patent No. 1,404,687 to Dehn. In the latter case, detonating primary or primer charges of diazodinitrophenol are used to initiate secondary or base charges of explosives, which are usually of the non-primary detonating type, such as tetryl and the like, the secondary or base charge initially detonating under the action of the primary charge. In U. S. Patent No. 1,759,565 Crater discloses nitrolactose as an explosive of this latter, non-primary type for use as a su stitute for or in admixture with tetryl and the like wherein fulminate-chlorate, lead azide, diaaodinitrophenol, etc., are employed as the prinary or initial primer detonating substances. But, in contradistinction to non-primary detoiating types of explosives, nitromannite, nitroiulcite, nitrolactose and the like are now known function as primary detonator charges when nerely ignited by means of suitable deflagrating lash compositions, as described in U. S. Patents 28,204 to 1,928,208 to Large.

The following will serve to illustrate the wdde ifference existing between the functioning of iazodinitrophenol as the detonating primary harge in a conventional compound detonator, nd its functioning as an ignition medium for 1e relatively new safety type primary charges 1 accordance with the present invention. lhereas, for example, a conventional type of impound detonator, containing a base charge tetryl in a .222" inside diameter shell reiires a primary charge of diazodinitrophenol insisting of at least about .20 gram pressed at i lbs. total pressure beneath a perforated inner .psule to obtain detonating initiation of the tryl, a detonator, in accordance with the pres- Lt lnvention, and containing the same tetryl se charge in the same size shell but containing .20 gram primary charge of nitromannite a.

essed at 75 lbs. total pressure beneath the same :e inner capsule, requires only as little as .02 am flash charge of diazodinitrophenol to efztively ignite the primary charge which adnces from ignition to detonation.

From the foregoing it will be evident that the' Lounts of diazodinitrophenol (or compositions uprising diazodinitrophenol) employed as sh charges in detonators of the present invenn are substantially less than those required for i as primary detonating compositions in deto- A fuse cap comprising a .222" inside diameter shell, a base charge of .2 gram of tetryl pressed therein at about 150 lbs. total pressure, a primary charge of .2 gram of nitromannite and superimposed thereon a flash charge of .01 gram diazodinitrophenol; the said primary and flash charges being pressed in one operation at 10 lbs. total pressure (273 lbs/sq. in.).

Example 2 A fuse cap similar to Example 1, but with the said flash charge consisting of .08 gram diazodlnitrophenol and with the said primary and flash charges pressed in one operation at lbs. total pressure (682 lbs/sq. in.). 25

Example 3 A fuse cap similar to Example 1, but with the said flash charge consisting of .02 gram diazodinitrophenol and with the said primary and flash charges pressed under a perforated inner capsule at 75 lbs. total pressure (2047 lbs/sq. in.).

Example 4 A fuse cap comprising a .222" inside diameter shell, a base charge of .2 gram of tetryl pressed therein at about 150 lbs. total pressure, a primary charge of .2 gram of nitromannite pressed under a perforated inner capsule at 75 lbs. total pressure, and a flash charge of .05 gram of diazodinitrophenol superimposed upon the said primary charge and inner capsule and seated at a total pressure of 75 lbs. (2047 lbs./sq. in.).

Example 5 An electric detonator comprising a .260" inside diameter shell, a base charge of .2 gram of tetryl pressed therein at about 175 lbs. total pressure, a primary charge of .2 gram of nitromannite pressed under a perforated inner capsule at 90 lbs. total pressure, and a loose'flash charge of .08 gram diazodlnitrophenol superimposed upon the said primary charge and inner capsule and surrounding an electric bridge-wire.

Emample 6 A fuse cap comprising a .222" inside diameter shell, containing .35 gram nitromannite pressed therein under a perforated inner capsule at 100 lbs. total pressure and a flash charge consisting 00 of .05 gram of diazodinitrophenoi pressed above the inner capsule at 75 lbs. total pressure. (2047 lbs/sq. in.)

Although amounts of inflammable compositions comprising diazodinitrophenol ranging from .01 to .15 gram have been found to function satisfactorily as ignition media in detonators having inside diameters of .222", it will be understood that the amount selected for use will vary over a considerable range; depending on 70 the type and diameter of detonator involved. Height of charge of the ignition medium is an important criterion in selecting the amount to be used. For example, in a fuse cap having an inside diameter of about .222", it is desirable to employ at least .05 gram of diazodinitrophenol, having a charge height of about .05 inch after being pressed at 75 lbs. total pressure, in order to provide enough of the material to form a pressed charge that will resist rumbling out. By "rumbling out is meant the breaking away or loss of a portion of the charge due to the detonator being jarred or subjected to vibration during manufacture, handling, shipping, etc. Also, for electric detonators, it is desirable to employ sufficient material to adequately cover the bridgewire used, which should range from about .12 to about .20 inch. For example, an electric detonator, having an inside diameter of about .260",

would require from about .08 to about .13 gram charge of loose diazodinitrophenol. Depending upon the type of detonator and type of flash charge, the height of flash charge may vary from .02 to .25 inch. In order to maintain these heights within detonator shells having larger diameters than those recited above, it will be evident that greater weights of charge will be required, without departing from the invention.

The present invention contemplates the use of diazodinitrophenol, in the manner described, either alone or admixed with other ingredients, such as for example; nitrolactose, nitroinositol, nitrodulcite, nitrostarch, nitromannite, oxygendelivering compounds, such as potassium chlorate, potassium perchlorate, ammonium perchlorate, barium nitrate, barium peroxide, lead oxides, and the like, etc. Examples of mixtures found to function quite satisfactorily are as follows: potassium chlorate, ammonium perchlorate, or nitromannite mixed in proportions up to 50% with diazodinitrophenol. Barium nitrate has also proved satisfactory in amounts up to 25% when mixed with diazodinitrophenol. As little as .05 gram of each of the above mixtures will efiectively ignite caps each having .20 gram tetryl base charge and .20 gram of nitromannite primary charge, confined under an inner capsule; the flash compositions being pressed above the capsule, in each case, at pressures ranging up to 150 lbs. dead weight in .222" inside diameter shells (4100 lbs/sq. in.). Flash compositions .comprising diazodinitrophenol and other admixed ingredients may be prepared in various suitable ways, as for example: dry mixing, wet mixing, co-precipitation from a mutual solvent, etc.

From the foregoing examples, it can be seen inositol, nitrodulcite, nitrostarch or nitromannite, have been found to be highly desirable for the formation of compressed flash charges, such compositions being highly resistant to rumbling out during manufacturing, handling, etc., even though pressed at pressures below 600 lbs./sq. in. The following examples are exemplary of this embodiment of the invention:

Example 7 A fuse cap similar to Example 7 but with a flash charge of .06 gram of a flash composition consistingof 25% nitrostarch and 75% diazodinitrophenol.

Example 9 A fuse cap similar to Example 7 but with a flash charge of .06 gram of a flash composition consisting of 25% nitromannite mixed with 75% diazodinitrophenol.

Example 10 A fuse cap similar to Example 7 but with a flash charge of .05 gram of a flash composition 7 consisting of 25% nitroinositol mixed with 75% that where the ignition medium embodying the present invention is in the form of a compressed flash charge, usually preferred for open fuse caps, the pressure employed in pressing the ignition mediummay vary over wide limits, particularly where the diazodinitrophenol is admixed with other ingredients. However, these compressed flash charges most effectively ignite safety type primary detonator composition when relatively low pressure is employed in pressing the flash charge, and generally,'the pressure employed in pressing the flash charge is lowered as the diazodinitrophenol content is reduced and as the proportion of admixed ingredients (other than diazodinitrophenol) is raised. Preferably, compressed flash charges embodying the present invention are lightly compressed, i. e., formed under pressure below 50 lbs. total in a .222" diametershell or below 1365 lbs./sq. in. Flash compositions comprising diazodinitrophenol admixed with a combustible, organic nitrate bind; ing ingredient which becomes coherent when subjected to pressure, such as nitrolactose, nitrodiazodinitrophenol.

Example 11 A fuse cap similar to Example 7 but with a flash charge of .06 gram of a flash composition consisting of 25% nitrolactose mixed with 75% diazodinitrophenol and with the said primary and flash charges pressed in one operation at lbs. total pressure (546 lbs/sq. in.)

We have found that the amount of diazodinitrophenol in certain open type fuse caps embodying the present invention may be selected so as to give a high degree of protection against the a primary charge, and a flash charge consisting of diazodinitrophenol in an amount not greater than about .05 gram, the said primary and flash charges being pressed in one operation at about 20 lbs. total presure (546 lbs. per sq. in.), the primary charge consistently failed to detonate when the flash charge was ignited by the spit of a Clover" fuse directed into the open end of the cap from a distance of atleast in. outside the open end of the cap. On the other hand, such detonators consistently fired from the spit of the Clover fuse when the fuse was inserted into the open end of the cap, even though the cap was not crimped upon the fuse. Similarly, in detonators having a base charge of .24 gram tetryl pressed at about 150 lbs.; a primary charge of .17 gram nitromannite and a flash charge of not more than about .08 gram of an inflammable composition consisting of 75% diazodinitrophenol and 25% nitromannite, the primary charge and flash charge being pressed in one operation at 20 pended claims, the term primary detonator composition" (or "charge) means the material used as the main charge in so-called simple or single charge detonators; or that used as the primary or top explosive charge in so-called com- 5 lbs. total presure (546 lbs. per sq. in.), the primary charge consistently failed to detonate when pound" detonators, in which are employed exthe flash charge was ignited by the spit of a plosive base charges, usually of the non-primary "Clover fuse directed into the open end of a detonating type. cap from a. distance of $4, in, or more, but con- By the term ignition medium, we mean the sistently fired when the fuse was inserted into charge of inflammable material used above the the end of the cap, even though the cap was not primary detonator charge which functions to crimped about the fuse. With flash charges conreceive ignition by such means as the end-spit sisting of a 75%-25% mixture of diazodinitroof a safety-fuse, the spit of a delay element in phenol and nitrolactose or nitrostarch, the fuse a delay type detonator, the heat of an electrically caps will pass this test even though larger heated bridge wire embedded therein, the fiash of I amounts (up to about .15 gram) of similarly a pre-formed fuse-head, the heat of an electric pressed flash composition are employed. In this Spark across electric terminals adjacent to or respect, the critical amounts of flash composiembedded therein, etc. and to subsequently ignite tions consisting of diazodinitrophenol and nitroe Said prim y d on o charge It y dulcite are somewhat lower, however, and where, be in a loose form, as preferred for example for 5 for example a '75%-25% mixture of these i surrounding electric bridge wires in electric detogredients pressed at about 546 lbs/sq. in. is emn tors; it may be in a mpr form, as p ployed as a flash charge for a primary detonator ferred for open fuse p t may be charged in charge of nitromannite, the amount of flash coma wet paste form and subsequently dried; etc.

position should not exceed about .06 gram if the Examples of safety types of primary detona- 2 fuse cap is to pass this test. tor charges, as defined above, which are con- From the above non-limiting examples, it will templated for use in carrying out our invention, be evident that we have a wide range of subare as follows: (1) solid nitration products of stances from which to choose, for use as admixed polyhydric alcohols of the general formula ingredients with the diazodinitrophenol in our CnHn+2(OH)n (as nitrodulcite, nitromannite, novel types of detonators; we being limited only etc.) alone or admixed with various proportions with respect to the properties desired in the parof other solid explosives, materially less sensiticular styles of detonators involved. For examtive than fulminate of mercury, lead azide, diazopie, for use in open-type fuse caps, we may prefer dinitrophenol and. the like (examples of such to use diazodinitrophenol alone or mixed with other solid explosives being tetryl, nitrolactose, other non-hygroscopic ingredients, whereas for nitropentaerythrite, etc); primary detonator use in closed-type electric detonators, we may compositions of this type having been disclosed choose iessmoisture resistant mixtures, etc. Exin U. S. Patents Nos. 1,928,204, 1,928,205 and tensive tests have shown definite advantages for 1,928,206 to Large; (2) solid disaccharide nitric 40 'diazodinitrophenol as to moisture resistance, as esters (as nitrolactose), alone or admixed with 40 compared with other materials heretofore provarious proportions of other solid explosives, posed for suitable use as ignition media for materially less sensitive than fulminate of mersafety" types of primary detonator compositions cury, lead azide, diazodinitrophenol and the like, in the form of superimposed layers or wafers. as disclosed in U. S. Patent No. 1,928,207 to Electrically fired detonators embodying the Large; etc. 45 present invention have been found to be highly It should be clearly understood that a. peradvantageous in that they have more uniform forated inner capsule, for the confinement of firing time than has been heretofore obtained the safety type of primary charge, may be with commercial detonators having a safety" used or not, in carrying out the present inven- 5 type primary charge. Thus, with the commertion. Although the use of an inner capsule has cially available detonators having an electrically certain advantages, as for example: (1) the hindfired, pre-formed fuse head which imparts igniing action between the capsule and shell tends to tion directly to the "safety type primary detohold the charge in place in a more positive mannator composition, the time interval between the hen-particularly when very low seating presfirst and last to fire of ten detonators in series sures are used and (2) it provides added confine- 55 averages about .0011 second, when fired with an ment for the primary charge; nevertheless we Atlas 3-50" blasting machine through a total may eliminate the inner capsule for the sake of of 50 ohms resistance. whereas with electric preeconomy, without departingfrom the invention. formed fuse head ignition of a fiash charge com- We have also discovered that the diazodinitroprising dlazodinitrophenol, which in turn infiames phenol type of ignition medium, superimposed the "safety type primary detonator composition, upon the safety type of primary detonator we have been able to reduce this time interval charge, will function beneath as well as on top of to less than .0002 second. For example, electric an inner capsule when and if used to confine the detonators having a base charge of .23 gram said primary charge. It will therefore be under- 5 tetryl, a primary charge of .12 gram nitromanstood that the invention is broad in this respect,

nite, a fiash charge of .06 ,gram of a composition as longas the ignition medium is positioned beconsisting of 75% diazodinitrophenol and 25% tween the primary detonator charge and the nitrom'annite, the primary charge and the flash source of heat (safety fuse end-spit, fuse-head, charge being confined under a capsule, and an etc.). It has been found preferable, however,

electrically fired, pre-formed match head for to position the ignition medium outside or on 70 top of the confining inner capsule, when and if the latter is used-particularly for fuse "capsin order to present a larger surface area of ignition medium to receive the end-spit from the safety fuse when inserted and crimped therein.

ignition of the fiash charge, gave an average time" interval of about .00007 second between the first and last to fire of ten detonators connected in series.

,- Where referred to in this specification and ep- One advantage of placing the ignition medium under the inner capsule, however, is that the capsule. helps to keep the flash composition in place during handling, shipment, etc., particularly when low seating pressures and/or very thin layers of the flash composition are employed.

From the foregoing, it will be evident that the present invention is applicable to all types and sizes of detonators wherein safety types of primary detonator compositions, as defined above, are employed.

The amount of safety type of primary detonator composition employed is also incidental and non-limited with respect to the present inventlon, and with so-called simple" or single charge detonators is merely dependent upon the type and strength of detonator desired, and with compound detonators is merely dependent upon the minimum amount required to detonate practically and consistently the explosive base charges employed. For example, so-called "simple or single charge detonators (i. e., without'a secondary or base charge), having a strength range that is comparable with that of certain conventional types in common use, may comprise a safety primary charge consisting of .10 to .85 gr. nitromannite and an ignition medium consisting of .01 to .15 gram or an inflammable composition comprising diazodinitrophenol. Greater or less than the above amounts of nitromannite may be used, however, without departing from the invention.

Similarly, in the case of compound type detonators, the invention is unrestricted as to the number, kind or amount of explosive base charges employed. For example, tetryl in amounts of from .15 to 1.25 grams has been found to be suitable as a base charge.

What we claim is:

1. In a detonator, the combination of a primary charge consisting of safety type primary detonator composition, and for the ignition of the said primary charge, an ignition medium comprising not more than .15 gram diazodinitrophenol, said ignition medium serving to inflame the said primary charge so that it will advance to detonation, and said ignition medium being incapable of directly detonating a non-primary detonator charge of tetryl.

2. In a detonator, the combination of a primary charge consisting of a safety type primary detonator composition, and an ignition charge comprising diazodinitrophenol positioned to become ignited from a source of heat and to transfer ignition to the said primary charge, said ignition charge being in the form of a layer having a thickness of from .02 to .25 inch, said ignition medium serving to inflame the said primary charge so that it will advance to detonation, and said ignition medium being incapable of directly detonating a non-primary detonator charge of tetryl.

3. A detonator including a primary charge consisting of a safety type primary detonator composition, and an ignition medium for the said primary charge consisting of from .01 to .15 gram of an inflammable material comprising at least .01 gram and at least 50% by weight of diazodinitrophenoL' said ignition medium serving to in flame the said primary charge so that it will advance to detonation, and said ignition medium being incapable of directly detonating a nonprimary detonator charge of tetryl.

4. A detonator including a primary charge consisting of a safety type primary detonator composition comprising a solid nitration product of a polyhydric alcohol of the general formula CnHn+2(oH)n, and an ignition medium for the said primary charge consisting of from .01 to .15 gram of an inflammable material comprising at least .01 gram and at least 50% by Weight of diazodinitrophenol, said ignition medium serving to inflame the said primary charge so that it will advance to detonation, and said ignition medium being incapable of directly detonating a non-primary detonator charge of tetryl.

5. In an open ended fuse cap, the combination of a primary charge consisting of safety type primary detonator composition and for the ignition of said primary charge, a lightly compressed ignition charge consisting of .02 to .15 gram of an inflammable material comprising a combustible binding material which becomes coherent when subjected to pressure and at least 50% by weight of diazodinitrophenol, said binding material being present in suficient amount to prevent rumbling out of the lightly compressed ignition charge, said ignition charge, when ignited by the spit of a fuse inserted into the open end of the cap, serving to fire the primary charge so that the primary charge will advance to detonation, and said ignition charge being present in an amount and under confinement insuiflcient to fire the primary charge so that the primary charge will detonate when the ignition charge is ignited by the spit of a fuse directed into the open end of the cap from a distance of at least /8" outside the open end of the cap.

6. In an open ended fuse cap, the combination of a primary charge consisting of safety type primary detonator composition and for the ignition of said primary charge, an ignition charge consisting of from .01 to .15 gram of an inflammable material comprising at least .01 gram and at least 50% by weight of diazodinitrophenol, said ignition charge, when ignited by the spit of afuse inserted into the open end of the cap, serving to flre the primary charge so that the primary charge will advance to detonation, and said igni-i tion charge being present in an amount and under confinement insuficient to flre the primary charge so that it will detonate when the ignition charge is ignited by the spit of a fuse directed into the open end of the cap from a distance of at least A; inch outside the open end of the cap.

7. In an open ended fuse cap, the combination of a primary charge consisting of nitromannite,

and for the ignition of said primary charge, an

ignition charge consisting of from .01 to .15 gram of an inflammable material comprising at least .01 gram and at least 50% by weight of diazodinitrophenol, said ignition charge, when ignited by the spit of a fuse inserted into the open end of the cap, serving to fire the primary charge so that the primary charge will advance to detonation, and said ignition charge being present in an amount and under confinement insumcient to flre the primary charge so that it will detonate when the ignition charge is ignited by the spit of a fuse directedinto the open end of the cap from a distance of at least A; inch outside the open end of the cap.

8. In an open ended fuse cap, the combination of a primary charge consisting essentially of nitromannite, and for the ignition of said primary charge, a flash charge consisting of from .02 to .10 gram of an inflammable composition comprising nitromanni-te and at least 50% by weight of diazodinitrophenol, said flash charge serving to fire the primary charge so that the primary charge will advance to detonation when the flash charge is ignited by the spit of a fuse inserted into the open end of the cap, and said flash charge being present in an amount and under confinement insumcient to flre the primary charge so that it will detonate when the flash charge is ignited by the spit of a fuse directed into the open end of the cap from a distance of at least inch outside the open end of the cap.

9. In an open ended fuse cap, the combination of a primary charge consisting essentially of nitromannite, and for the ignition of said primary charge, a flash charge consisting of from .02 to .15 gram of an inflammable composition comprising nitrolactose and at least 50% by weight of diazodinitrophenol, said flash charge serving to fire the primary charge so that the primary charge will advance to detonation when the flash charge is ignited by the spit of a fuse inserted into the open end of the cap, and said flash charge being present in an amount and under confinement insuflicient to fire the primary charge so that it will detonate when the flash charge is ignited by the spit of a fuse directed into the open end of the cap from a distance of at least 4, inch outside the open end of the cap.

10. A compound detonator comprising a base charge consisting of .15 to 1.25 grams tetryl, a primary detonator charge consisting of .10 to .25 gram of safety type detonator composition, and superimposed thereon an ignition medium consisting of from .02 to .10 gram of an inflammable material comprising at least one compound taken from the group consisting of:. nitrolactose, nitroinositol, nitrodulcite, nitrostarch and nitromannite and at least 50% by weight of diazodinitrophenol, said ignition medium serving to inflame the said primary charge so that it will advance to detonation, and said ignition medium being incapable of directly detonating a non-primary detonator charge of tetryl.

11. A compound detonator as set forth in claim 10 and wherein the primary detonator charge consists essentially of nitromannite and the flash charge consists essentially of nitromannite and diazodinitrophenol.

12. A detonator comprising a primary explosive dium serving to inflame the said primary charge 1 so that it will advance to detonation, and said ignition medium being incapable of directly detonating a non-primary detonator charge of tetryl.

13. A detonator as set forth in claim 12 and wherein the-primary detonator charge consists ll essentially of nitromannite and the flash charge consists essentially of nitromannite and diazodinitrophenol.

14. A detonator comprising a shell, a primary detonator charge consisting of safety type primary detonator composition so compressed and confined in the shell that it is capable of advancing from ignition to detonation when ignited by a suitable non-detonating flash composition, and for the ignition of said primary charge an ignition medium comprising not more than .15. gram diazodinitrophenol, said ignition medium being incapable of directly detonating a non-primary detonator charge of tetryl. 15. A detonator comprising a shell, a main charge in the shell free of all explosives as sensitive to friction and impact as mercury fulminate, lead azide, diazodinitrophenol and the like, said main charge havingat least a portion thereof consisting of a "safety type primary detonator composition so compressed and confined in the shell that it is capable of advancing from ignition to detonation when ignited by a suitable non-detonating flash composition, and for the ignition of said primary detonator composition an ignition medium positioned to become ignited by a source of heat and to transfer ignition to the said primary detonator composition, said ignition medium consisting of from .01 to .12 gram of an inflammable material comprising at least .01

gram and at least 50% by weight of diazodinitrophenol.

SYLVESTER B. LARGE. GUY F. ROLLAND.