Non-electric detonators without a percussion element

A non-electric detonator device having a tubular shell that is closed at its bottom end and containing PA0 a base charge of a detonating explosive at the bottom of the shell, PA0 a priming charge of a heat sensitive detonating explosive composition adjacent to the base charge, PA0 a rupturable membrane that seals the top end of the shell and forms an open volume between the priming charge and the top end of the shell and PA0 a holder for holding a low energy detonating cord (LEDC) in abutting relationship to the membrane: whereby on detonation of the LEDC the membrane is ruptured and the priming charge is initiated which in turn initiates the detonating explosive.

BACKGROUND OF THE INVENTION 
This invention relates to a non-electric detonator for explosives and in 
particular to a non-electric detonator that does not contain a percussion 
element. 
The safety of blasting operations has been greatly improved by the use of 
non-electric detonators actuated by a low energy detonating cord (LEDC). 
Typical non-electric detonators and assemblies using these detonators and 
LEDC lines are shown in Yunan U.S. Pat. No. 4,426,933 issued Jan. 24, 
1984, Mitchell, Jr. et al. U.S. Pat. No. 4,495,867 issued Jan. 29, 1985, 
Day et al. U.S. Pat. No. 4,539,909 issued Sept. 10, 1985, Bryan U.S. Pat. 
No. 4,335,652 issued June 22, 1982, Yunan U.S. Pat. No. 4,424,747 issued 
Jan. 10, 1984, Yunan U.S. Pat. No. 4,248,152 issued Feb. 3, 1981, and 
Yunan U.S. Pat. No. 4,429,632 issued Nov. 11, 1980. However, these 
non-electric detonators require intimate contact between the LEDC, the 
percussion element or shell containing a layer of a sensitive explosive 
material. Such structures work on shock transmission either to initiate 
the sensitive explosive or to pinch the powder in the percussion element 
against an anvil or rim. These detonators with either a percussion element 
or a shock sensitive explosive contained in a shell may fail to initiate 
the detonator due to poor cord to element contact and may under some 
circumstances be accidentally triggered to set of the explosive charge. To 
further improve the safety of detonators, it would be desirable to either 
eliminate the percussion element or conceal and protect the sensitive 
explosive in a plastic body. This invention makes possible the design of a 
detonator without a percussion element or without an exposed portion of a 
shell containing a sensitive explosive for use with a LEDC that would 
consistently fire and be reliable for use in a blasting assembly. 
SUMMARY OF THE INVENTION 
A non-electric detonator device comprising a tubular shell closed at its 
bottom end and having 
(a) at least one base charge of a detonating explosive composition located 
in the bottom of the shell, 
(b) a priming charge of a heat sensitive detonating explosive composition 
adjacent to the base charge that does not fill the shell, 
(c) a rupturable membrane that seals the top end of the shell and forms an 
open volume between the priming charge and the top end of the tubular 
shell and 
(d) means for holding low energy detonating cord (LEDC) positioned in 
abutting relationship to the membrane; 
whereby on detonation of the LEDC the membrane is ruptured and the priming 
charge is initiated which in turn initiates the detonating explosive. 
Included in this invention is an assembly of the detonator device, LDEC and 
an explosive charge.

DETAILED DESCRIPTION OF THE INVENTION 
The present invention is based on the discovery that intimate contact 
between detonating cord and percussion element or a shell containing a 
shock sensitive explosive is not required for a reliable non-electric 
detonator that uses a LEDC, i.e. a cord having a pentaerythritol 
tetranitrate (PETN) core loading of about 0.10-2 grams per meter. The 
detonators of this invention have a high level of reliability for firing. 
Since the detonator does not contain a percussion element or a shock 
sensitive explosive in the exposed portion of the shell, it is inherently 
safer to handle and premature triggering of an explosive charge is 
practically eliminated. 
FIG. 1 shows a side view of the molded plastic body that holds the 
detonator that has a fixed slot 1 for attaching the input or initiating 
LEDC 3a and another fixed holder 2 for attaching two output LEDC 3b that 
are to be initiated by explosives in the detonator. The body is plastic 
such as polyethylene or polypropylene. Thermosetting plastics such as 
molded rubber compounds like styrene/butadiene rubber can also be used. 
The tubular shell containing the explosive components is positioned in 
this body, as shown in detail in FIG. 2. 
FIG. 2 is a cross section of FIG. 1. The cross section of the fixed slot 1 
which holds the input LEDC 3a is shown and its relation to the main 
portion 5 of the plastic body. The input end 4 of the plastic body is a 
cavity designed to accept and secure different diameter electric or 
non-electric initiating devices, which when fired rupture membrane 7 and 
initiate the primer charge 9. Shell 6, usually metal and preferably 
aluminum is positioned in the body 5 through opening 11 and held in place 
by a friction fit. Hinge 2 is closed and becomes fixed to hold output LEDC 
3b in place. The shell contains in its base a detonating explosive 10, 
also known as the base charge. Typical base charges that can be used are 
pentaerythritol tetranitrate (PETN), cyclotrimethylene trinitramine, 
cyclotetramethylene tetranitramine, lead azide, picrylsulfone, 
nitromannite, trinitrotoluene (TNT) and the like. Covering the base charge 
is a priming charge 9 that can be flat or tapered and imbedded in the base 
charge or detonating explosive. Typical priming charges are of lead azide, 
lead styphnate, diazodinitrophenol, mercury fulminate and nitromannite. 
Mixtures of diazodinitrophenol/potassium chlorate, 
nitromannite/diazodinitrophenol and lead azide/lead styphnate also can be 
used. A separate layer of lead styphnate or a layer of a mixture of lead 
styphnate can be placed over lead azide. 
The top of the shell 6a generally is slightly round to facilitate its 
insertion and is sealed with a rupturable membrane 7 that ruptures when 
the LEDC is ignited. 
A U or V shaped LEDC cord configuration may be used for either or both ends 
of the detonator to penetrate a thicker membrane or ignite a less 
sensitive powder. This type of configuration is shown in Yunan U.S. Pat. 
No. 4,424,747 issued Jan. 10, 1984. 
The open space between the priming charge 9 and the rupturable membrane 7 
is represented by 8 and is a distance of about 1/32-11 inches, preferably 
about 1/2-21/2 inches is used for an instantaneous charge. If a delay 
charge or an ignition powder is used, 1/32-1/2 of an inch is preferred. It 
is known that slower burning rates of delay powders can be obtained by 
increasing the open space 8. Means to quickly pressurize and improve 
timing of delay detonators with enclosed open space are discussed in the 
aforementioned Yunan U.S. Pat. No. 4,429,632. 
Shorter open space distances are normally preferred between the membrane 
and the explosive charge. However, under some circumstances a long tube or 
shell up to ten inches in length, similar in arrangement to FIG. 3, may be 
needed to pass the shock from the LEDC cord through sensitive surroundings 
such as electrical components or connectors which could be damaged by a 
shock wave from either the LEDC or the explosive charge but which of 
course may be easily isolated by containing the output of the explosive 
using insulating material in available space. 
FIG. 3 shows cross section of a LEDC cord holder containing LEDC cord 3a 
attached to shell 6 containing the detonating base explosive 10 and the 
priming charge 9 positioned flatly against the base explosive. A plastic 
LEDC holder 12 having a fixed slot is positioned over the end of the shell 
containing the rupturable membrane 7 and there is an open space 8 between 
the priming charge and the rupturable membrane. Such a device can be used 
to initiate other explosive devices. The holder 12 can be designed to 
accept more than one LEDC. 
FIG. 4 A shows a plastic holder for the shell having two hinged holders for 
the LEDC. FIG. 4 B shows a cross section of the plastic holder having an 
electric or non-electric detonator 4a or high energy detonating cord 
positioned in cavity 4b and a shell 6 positioned in the body of the 
plastic holder and two output LEDC 3b held by the hinged holder. Shell 6 
is shown empty and may be any one of the shells shown in FIGS. 8 and 9. 
FIG. 4 C shows the cross section of a plastic holder having fixed LEDC 
holders on either end containing LEDC 3a and 3b and a shell 6 positioned 
in the holder. 
FIG. 5 A shows a side view of a plastic holder having one hinged holder for 
one or two output LEDC and a fixed holder for input LEDC. FIG. 5 B shows a 
cross section of FIG. 5 A in which an initiator 4a is positioned in the 
cavity 4b. The initiator may be an electric or non-electric detonator or a 
high energy detonating cord which when fired shatters the membrane 7 and 
ignites the explosives in the shell 6. Two output LEDCs 3b are held in 
place by the hinged holder. 
FIG. 6 shows a shell 6 having a fixed plastic holder 12 for the input LEDC 
3a and another fixed plastic holder 13 for the output LEDC 3b separate 
from holder 12 which gives the freedom of using any length shell. The two 
part plastic body shown in FIG. 6 is not restricted to holders 12 or 13 
but may be any of the aforementioned holder designs. 
U.S. Pat. No. 4,426,933 shows a connector that fits over a shell. This 
connector which can be made of plastic or metal may be made with a 
rupturable membrane and made to fit inside the shell or over the shell. 
The rupturable membrane may be part of the plastic connector as shown 
previously or may be part of a cap needed to seal the shell as shown in 
FIGS. 7A and B. The sealed shell with its own rupturable membrane may then 
be inserted in any of the previously described connectors, without a 
rupturable membrane to give the same performance. 
FIG. 7 A shows upper portion of a shell 6 with a plastic or metal cap 12A 
having an interference fit between the outer walls of the cap and the 
inner walls of the shell 6. A rupturable membrane is in the top of the cap 
and an open space 8 is below the rupturable membrane. FIG. 7 B shows the 
upper portion of a shell 6 with a plastic or metal cap 12B having an 
interference fit between inner walls of the cap and the outer walls of the 
shell. A rupturable membrane is in the top of the cap and an open space 8 
is below the rupturable membrane. The interference fit between the cap and 
the shell walls is used to keep moisture out of the shell. Crimps to form 
a seal as shown in Yunan U.S. Pat. No. 4,426,933 may be used to improve 
moisture seals. Adhesives may also be used to improve moisture seals. 
The rupturable membrane can be of the aforementioned plastic or 
thermosetting plastic materials or of a thin metal such as aluminum, brass 
or steel; aluminum is preferred. If the membrane is a metal it is about 
about 1-10 mils thick, preferably about 3-5 mil thick. If the membrane is 
a plastic, it is about 5-30 mils thick, preferably 8-12 mils thick. The 
plastic rupturable membrane may be flat and covers and seals the mouth of 
the shell. Other geometric configurations that facilites rupturing can be 
used on the membrane such as a cross, triangle, star and the like. 
FIGS. 8 and 9 show shells containing explosives charges and may be inserted 
into the aforementioned connectors. These figures show possible 
combinations of explosive compositions and their schematic representations 
are not to scale. 
FIG. 8 shows cross sections of various configurations of instantaneous 
detonators. FIG. 8 A shows a shell 6 containing the detonating base 
explosive charge 10 and a primer charge 9 imbedded in the base charge 10. 
FIG. 8 B shows the shell 6 containing the base charge 10 and the primer 
charge 9 pressed flatly over the base charge 10. Both types of primer and 
base charges will work in this invention. In the following figures only 
the embedded priming charge will be shown. FIG. 8 C shows two separate 
primer charges 9 and 9a in shell 6 pressed in contact with the base charge 
10. Charge 9a is usually more sensitive than charge 9. Lead styphnate or 
one of the aforementioned mixtures of lead syphnate can be used for charge 
9a. 
FIG. 8 D shows a shell 6 with a capsule 17 having an orifice 17a positioned 
over the primer charge 9. The capsule is desired from a safety standpoint 
to press the primer charge in place. 
FIG. 8 E shows a spacer 16 with an inner hole 16a needed for pressing the 
primer charge 9 over in the base charge 10. Spacer has an upper taper to 
direct the detonation from the open space to the primer. The lower taper 
is present for symmetry. 
FIG. 8 F is the same as FIG. 8 E except that the spacer 16 is not tapered 
and the space inside the spacer is filled with loose or pressed primer 
powder 9 or 9a which is embedded in the base charge 10. 
FIG. 8 G is the same as FIG. 8 F except that another primer charge 9 or 9a 
is positioned over the spacer 16. The primer 9b is shown as a loose charge 
but may also be a pressed charge. 
FIG. 8 H contains a cup 19 with a rupturable bottom 19a positioned in the 
shell 6 and supported over the primer charge 9 by capsule 17. Loose or 
pressed primer charge 9 or 9a is in the cup. 
FIG. 8 I is the same as FIG. 8 H except a spacer 16 is positioned between 
the primer charge 9 and the cap 19. Spacer 16 may be empty as shown in 
FIG. 8 I or filled as shown in FIG. 8F. 
FIGS. 9 A through L show the cross section of delay detonators that can be 
used. In every case shell 6 contains a base charge 10 and an embedded 
primer charge 9. Delay timing is obtained by using delay charges which are 
essentially produced by gasless exothermic reaction mixture of solid 
oxidizing and reducing agents that burn at a controlled rate. Examples of 
such mixtures are boron-red lead, boron-red lead silicon, boron-red 
lead-dibasic lead phosphite, aluminum-cupric oxide, magnesium-barium 
peroxide, silicon-red lead and the like. 
FIG. 9A shows a delay powder 13 pressed over primer charge 9. 
FIG. 9B shows an empty spacer 16 with a hollow center 16a pressed over 
delay charge 13. 
FIG. 9C shows delay powder 13 inside the hollow center spacer 16, commonly 
known as a carrier. 
FIG. 9D shows a loosely loaded ignition charge 14 over pressed delay charge 
13. The ignition charge 14 may be loose as shown or pressed as shown in 
FIG. 9E. Ignition charges are normally more sensitive to initiation than 
some delay powders, especially when pressed. Normally delay powders are 
pressed. The ignition charge 14 may be a primer charge which does not 
contribute to additional timing. 
FIG. 9E is the same as 9D except the ignition charge 14 is pressed. 
FIG. 9F shows an ignition charge 14 over delay carrier 16 with delay powder 
13 in spacer 16. Ignition charge 14 may be pressed (not shown). 
FIG. 9G is the same as FIG. 9C, but also shows ignition powder 14 in cup 19 
supported by capsule 17 which has a rupturable membrane 19a. 
FIG. 9H is the same as FIG. 9C, but also shows another carrier 18 loaded 
with either priming powder 14 positioned over spacer 16 with delay charge 
13. 
FIG. 9I is the same as FIG. 9H, except that the carriers are reversed. Top 
carrier 16 contains delay powder 13. 
FIG. 9J has delay powder 13 pressed over carrier 16 which contains a primer 
powder 9a. 
FIG. 9K is the same as FIG. 9B, but shows carrier 16 containing ignition 
powder 14 pressed over delay powder 13. 
FIG. 10A shows an explosive charge 20 in a flexible container having a LEDC 
cord 3a wrapped around the container and positioned in plastic holder 12 
having a fixed slot positioned over the open end of the shell 6 of the 
detonator. The detonator contains a detonating base charge 10 and a 
priming charge 9 positioned over the base charge. A spacer 16 with its 
center filled with a primer charge 9a is positioned over the primer charge 
9. A delay powder 13 is positioned over the spacer. As shown in FIG. 3, 
the detonator has rupturable membranes and open space. 
FIG. 10B shows a block explosive charge 21 containing a detonator. LEDC 3a 
is positioned in the center cavity of the charge 21 and attached to the 
plastic holder 12 of the detonator positioned over the open end of the 
shell 6 of the detonator. The detonator contains a base charge 10, a 
priming charge 9 positioned adjacent to the base charge. There is a open 
space between the rupturable membrane 7 and the priming charge 9. 
FIG. 9L is the same as FIG. 9G, except delay powder 13 is pressed over 
primer charge 9. 
The following examples illustrate the invention. 
EXAMPLE 1 
Aluminum shells 1.67 inches long with 0.003 inch thin bottom were loaded 
with 8 grains of a base explosive of pentaerythritol tetranitrate (PETN) 
and pressed with a pin to form a cavity and then 3.6 grains of a primer of 
dextrated lead azide was loaded and pressed with a flat pin. The space 
between the lead azide and the open end of the shell was 1.2 inches. The 
shell was inserted open end first, into a cylindrical plastic with a 
closed membrane at the other end (see FIG. 3). The inner diameter of the 
cylindrical plastic body next to the membrane formed an interference fit 
against the outside walls of the cylindrical shell. The plastic body 
loaded with the shell was subjected to hydraulic pressure of 10 psi for 8 
hours. Upon examination the shell and its contents were found to be dry. 
A detonator was made as shown in FIG. 1, by placing a shell prepared as 
above in a plastic body and a LEDC 2.2 grain/foot (1.7 grain/foot PETN 
basis) was placed over the sealing membrane of the shell as a trunkline. 
The LEDC is described in Yunan U.S. Pat. No. 4,232,606 issued Nov. 11. 
1980. Two down lines of the same cord were placed against the bottom of 
the shell forming a "U" shaped configuration after closing the latch. The 
trunkline cord that was positioned against the thin membrane was fired and 
two downlines were initiated instantly by the detonator. The same 
detonator was made as above except a shell was used that had a 3 inch 
space between the cap with a sealing membrane and the sensitive explosive. 
This detonator also fired instantly. 
The above shows that reliable instantaneous detonators can be made for use 
with LEDC that do not contain a percussion element. 
EXAMPLE 2 
Four aluminum shells described in Example 1 were each loaded with 8 grains 
of PETN and 3.6 of dextrinated lead azide priming charge as in Example 1 
and each of the shells was loaded and pressed with a different level of a 
delay powder of boron/red lead/silicon (B/RL/S). Each shell was covered 
with a plastic connector to form a delay detonator as shown in FIG. 9A. A 
LEDC was connected to each shell and each shell was fired and timed. The 
results of the test are shown in the following table: 
______________________________________ 
Delay Powder (B/RL/S) 
Open space 
Ave. Timing 
(grains) (inches) (milliseconds) 
______________________________________ 
4 17/16 76 
17 13/16 234 
32 1/2 422 
42 11/32 553 
______________________________________ 
The above shows that delayed detonations can be obtained with the pressed 
delay powders. 
EXAMPLE 3 
An aluminum shell described in Example 1 was charged with a PETN and 
dextrinated lead azide load as in Example 1 and 3.0 grains of Type 15 red 
lead/silicon delay powder was pressed at 250 pounds over the lead azide 
load with a flat pin and 4.2 grains of Type 11 (B/RL/Si) loose ignition 
powder was loaded over the pressed delay powder which partially filled the 
open space in the shell. The shell was sealed by a plastic cap with 
rupturable membrane. An LEDC containing 3.2 grain/foot (2.4 grain /foot 
PETN basis) was used to fire the detonators. A series of detonators of the 
same construction were fired and the average fire time delay was 150 
milliseconds with 7 milliseconds standard deviation. It was conclude that 
good timing accuracy is possible with this type of detonator. 
EXAMPLE 4 
An aluminum shell described in Example 1 was charged with a PETN and lead 
azide as in Example 1 and a metallic carrier loaded with a delay powder 
was pressed over the lead azide charge (see FIG. 9C). There was a 1 inch 
open space between the metallic carrier and the rupturable membrane 
covering of the shell. Two additional detonators were prepared as above 
except the open space between the membrane and the metallic carrier was 
1/8 inch and 1/4 inch, respectively. An additional detonator was prepared 
as above with a 1 inch open space except loose delay powder (B/RL/Si) was 
placed over the metallic carrier (see FIG. 9F). The detonators were fired 
using the LEDC described in Example 1. The results are as follows: 
______________________________________ 
Number Shot 
Nominal Delay 
Open Space Loose Delay 
Per Total 
(milliseconds) 
(inches) Powder Tested 
______________________________________ 
125 1 None 0/2 
125 1 Yes(4 grain) 
2/2 
175 1/8 None 7/7 
175 1/4 None 6/11 
______________________________________ 
It is concluded that delay carriers may reliably be initiated directly from 
an LEDC and through a membrane at a spacing of 1 inch with the use of 
loose delay powder and at a spacing of 1/8 inch without loose delay 
powder. 
EXAMPLE 5 
Instantaneous detonators were prepared by loading aluminum shell with a 
primer and and explosive charge as in Example 1 with different lengths of 
open space and a plastic LEDC holder with a rupturable membrane was 
positioned over the open end of the shell to form a detonator as shown in 
FIG. 3. The detonators were then fired using the LEDC described in Example 
3. The results are shown below: 
______________________________________ 
Open space Average time (inches) 
(inches) (milliseconds) 
______________________________________ 
6 1.2 
10 1.4 
11 1.4 
12 failed 
______________________________________ 
It is concluded that a reliable initiation up to an 11 inch gap is possible 
with no indication of weakening of the propagation flame from the 
detonating cord.