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1. (WO1997019316) DETONATOR PACKAGING
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DETONATOR PACKAGING
Field of the Invention
The present invention relates generally to packaging for explosives and more particularly to packaging for detonators
Background of the Invention
As a safety precaution, explosive devices are generally packaged before being shipped If one of the explosive devices explodes, the packaging is supposed to prevent the explosive force from being transmitted to surrounding structures and personnel, thereby preventing damage to both In particular, the packaging is supposed to prevent the explosive force of a single detonation from initiating other explosive devices in the same shipment, which may start a chain reaction leading to mass detonation As used by those skilled in the art, the term initiate means to fire, or explode, an explosive device
As is known by those skilled in the art, the relative safety of packaged explosives is measured according to United Nations Certification numbers or classifications Most detonators are in class 1 IB, which means that they can mass detonate and, therefore, they must be shipped separately from other hazardous materials (except for mateπais having the same classification number) A 1 4B classification means that the explosives will not mass detonate and that they can be shipped with other hazardous mateπais As it will be understood, products having a 1 IB classification are much more expensive to ship than products having a 1 4B classification, because they must be shipped on a truck separate from other explosives An even more desirable classification is 1 4S, which means that the product can be shipped on commercial air-craft
Several types of containers or packages for explosives are known that comprise layers of absorbent foam and/or metal barriers to contain an explosive force None of these devices are practical for packaging detonators because they are expensive, whereas detonators are relatively low-cost items Further, because of the complexity of many of the known packaging designs, they could not be produced in a size suitable for packaging a detonator, which is generally about 3 inches long and has a diameter of approximately 3/8 mches Additionally, many of the explosives packages disclosed in the prior art are relatively heavy, which makes the assembled, packaged product difficult to handle and expensive to transport
Generally, detonators are packaged by first layering a cardboard carton with 1/2" thick Homeosote A 1 " thick section of Homeosote is then provided and about 10-15 holes are bored in this Homeosote section A detonator, having an explosive end, is then placed in each hole so that the explosive end is contained within the hole A plurahty of these boards containing detonators are placed in the carton with 1/2" thick Homeosote sheets placed between them This type of packaging is relatively heavy and it does not adequately contain the explosive force of the detonator and, therefore, does not adequately prevent mass detonations Additionally, it greatly reduces the available space within the carton Therefore, each carton contains a relatively small number of detonators and transportation costs are increased
Detonators are rated according to explosive force A number 8 detonator has the lowest explosive force and a number 12 detonator has the highest explosive force Using the packaging methods known in the prior art, it has been possible to achieve a 1 4B classification with number 8 detonators, but a 1 4B classification has not be achieved with more powerful detonators in a cost-effective manner and a 1 4S classification has never been achieved with detonators in a cost-effective manner

Summary of the Invention
The present invention solves these and other problems by providing a low-cost packaging that is light weight, easy to manufacture and that holds a relatively large number of detonators in a single carton
The invention comprises a casing for containing the explosive end of a detonator The casing is formed from a plurality of sections of relatively dense material, such as Homeosote, that are connected, preferably by an adhesive Preferably, the casing comprises three or more material sections, although it could also be formed from two sections Two of the sections form ends or sides of the casing and are called end sections and the other material sections are retained, or sandwiched between the end sections and are called interior sections An opening is formed in the casing and a detonator, or other explosive device, is received in the opening so that the explosive end is retained at least partially within one of the interior sections The casing absorbs most or all of the explosive force of the detonator and prevents the explosive force from initiating other detonators in the package
Each detonator preferably has a length of transmission tube, detonating cord or wire attached thereto In order to retain the casing a fixed distance from the transmission tube or detonator, the casing is placed in a cardboard spacer before being placed in the carton
It is therefore an object of the present invention to provide packaging for shipping explosives
Another object of the present invention is to provide packaging for shipping detonators
It is further object of the present invention to provide packaging for shipping detonators wherein the explosion of one detonator will not cause other detonators within a carton to explode
It is a further object of the present invention to provide detonator packaging comprising a casing formed from a plurality of material sections wherein the casing has an opening that extends into an interior material section A detonator is inserted into the opening and is retained at least partially within the interior material section
It is a further object of the present invention to provide detonator packaging comprising a casing as descπbed above attached to a spacer
It is a further object of the present invention to provide detonator packaging compπsing a carton containing a plurality of spacers each of which has a detonator attached thereto as described above
These and other objects will become apparent to those skilled in the art upon reading the following description and appended claims

Brief Description of the Drawings
Figure 1 is a perspective view of the casing according to the present invention
Figure 2 is an exploded, perspective view of the casing shown in Figure 1
Figure 3 shows a front, bottom and assembled bottom view of a spacer according to the present invention
Figure 4 shows a spacer separating the casing from transmission tubes
Figure 5 shows alternate casing structures in accordance with the present invention

Detailed Description of the Invention
Turning now to the drawings, where the purpose is to show a preferred embodiment of the invention, and not to limit same, Fig 1 shows a detonator 1 and a nonpropagation casing 10 according to the present invention Detonator 1 is generally an elongated, cylindrical member

Detonator 1 has an exterior casing 2, which is preferably formed of metal such as aluminum or steel, a first end 3 and a second end 4 First end 3 has an opening 5 formed therein, opening 5 being dimensioned to receive a transmission tube or detonating cord 6 The interior (not shown) ot detonator 1 has a series of explosive charges that can be initiated by transmission tube 6 The series of charges culminates in a high-energy explosive charge retained with second end 4 Second end

4, therefore, is also referred to as the explosive end of the detonator
Casing 10 is preferably formed of a material having a density of 26 lbs /ft1 to 28 lbs /ft 3 and is preferably formed from sections of Homeosote Other paper products, wood or plastics could also be used Less dense mateπais, such as corrugated cardboard or pressed paper would not adequately contain the explosive force when assembled in the configurations described herein Additionally, these materials create a fire hazard
Preferably casing 10 is formed of three layers, or material sections, 12, 14, 16, although two, or more than three, material sections could be used Material sections 12 and 16 are referred to as end sections, because they each form an end, or side, of casing 10 Material section

14 is referred to as an interior section because it is retained, or sandwiched, between end sections

12 and 16
Referring to Fig 2 material section 12 preferably is rectangular and preferably has a nominal dimension of 1-1/2" X 1 ' and a nominal thickness T of 1Δ " It will be understood, however, that material sections having any dimensions capable of absorbing the explosive force of the explosive device could be used The material sections used to form the present invention preferably all have the same dimensions and thickness, as this lends for simple manufacture and assembly, however, material sections having different dimensions and thicknesses could also be used Therefore, in the preferred embodiment sections 14 and 16 have the same dimensions and thickness as section 12
Material sections 12 and 14 are connected by an adhesive (not shown) disposed at intersection 18 Material sections 14 and 16 are preferably connected by an adhesive (not shown) disposed at intersection 20 Any adhesive capable of bonding material sections 12, 14 and 16 could be used The adhesive will be selected according to the material that forms sections 12, 14 and 16 Additionally, other connecting structures could be employed to connect sections 12 and 14 and 14 and 16 The adhesive connecting the material sections that form casing 10 is preferably a two-sided adhesive tape
Casing 10 has a first end 22, a second end 24 and sides 26, 28, 30 and 32 An opening 34 is generally elongated, cylindrical and preferably extends from first end 22 through sections 12 and 14, but does not penetrate section 16 In order for casing 10 to adequately absorb the explosive force of the detonator, the explosive end of the detonator should be positioned in an interior section, which is section 14 on casing 10 It will be understood, however, that depending upon the thickness and density of the material sections forming the casing, it is not always necessary that the explosive end of the detonator be positioned entirely within center section 14 It is only necessary that enough of the explosive end of the detonator be positioned within center section 14 to keep casing 10 from fragmenting and possibly initiating other detonators Therefore the explosive end of the detonator may be positioned partially within section 12 and/or 16 (depending on the thickness of the sections and the length of the explosive end) Additionally, if there is more than one interior section (for example, if casing is formed of four or more sections) opening 34 should extend at least partially into at least one of the interior sections The explosive end of the detonator may be positioned partially within one or more of the interior sections If the casing is formed of only two material sections, opening 30 should extend through one material section and at least partially into the second material section so that the explosive end of the detonator is positioned partially within each of the material sections
As shown in Fig 1 , sections 12, 14 and 16 are horizontally arranged to form casing 10 Alternatively, as shown in Fig 5, sections 12 , 14' and 16' are vertically arranged and connected in the manner previously described to form a casing 10' In this arrangement, an opening 34 is formed in the center section 14' and not in the two end sections 12 and 16 Additionally, only two blocks or more than three blocks may be vertically arranged and connected to form a casing in accordance with the present invention Furthermore, other arrangements of connected material sections may also be used Some examples are shown in Fig 5
As shown in Fig 4, a spacer 50 is preferably made of pressed paper or cardboard, although other materials could be used Spacer 50 is generally a single strip of material that is wrapped so that the ends overlap and glued to a loop In this way a plurahty of nonpropagation casings 10 may be neatly arranged and separated from one another A casing 10 having a detonator 1 and transmission tube 6 is preferably connected to interior wall 52 of spacer 50 Preferably an adhesive (not shown) is applied to side 26 of casing 10 Adhesive 36 is preferably a two sided adhesive tape Side 26 of casing 10 is attached to wall 52 of spacer 50 by the adhesive, although other means of attachment may be used Additionally, side 30 may be attached to the opposite side of interior wall 52 The purpose of attaching casing 10 to wall 52 is to further protect against mass detonation If detonator 1 , retained within opening 34 of casing 10, explodes, a small amount of shrapnel and energy may escape from casing 10 If casing 10 was improperly packed or has shifted during shipping it may be in close proximity with the transmission tubes In that case even a small amount of explosive force could possibly initiate the transmission tube, which would initiate the other detonators to which the transmission tube is connected By attaching casing 10 to wall 52, it insures that the detonator remains spaced from the transmission tubes during shipping Preferably, each casing is centered on a wall 52 within a 3" space formed between a coil of transmission tube Therefore, detonator 1 is preferably spaced 1-1/2" from a transmission tube, although other spacings could also achieve the desired result This same result could be accomplished by dimensioning the casing (e g , making it wider) so that a space is maintained between the casing and the transmission tubes
A carton (not shown) is preferably a corrugated cardboard box dimensioned to receive a plurality of spacers 50 having casings 10, detonators 1 and transmission tubes 9 Preferably the carton is dimensioned to contain 150 spacers 50 and, therefore, 150 detonators 1.
Having now described a preferred embodiment of the invention, modifications and alterations that do not depart from the spirit of the invention will become apparent to those skilled in the art. The invention is, therefore, not limited to this description, but is instead set forth in the following claims and legal equivalents thereof.