Note: Descriptions are shown in the official language in which they were submitted.
~ 3~ CIL 573
This invention relates to an assembly ~or the
non-electric initiation of an explosive charge. More par-
ticularly, the invention involves an assembly whereby an
initiating energy pulse may be transmitted from an energy
generator or energy emitter to a blasting cap or other
explosive device without resort to the use of any connecting
detonating, or deflagrating or burning fuse
The use of non-electric explosives initiation
systems are now well known in the blasting art Generally,
these systems comprise the use of one or more lengths of
detonating fuse cord each having attached at one end thereof
an instantaneous or delay blasting cap. When the opposite
end of the cord is initiated by means of an explosive initiator
such as a cap or priming trunk line fuse cord, the detonating
fuse is detonated and an explosive~ wave is transmitted along
its length at high velocity to sel: off the attached blasting
cap. The use of such a system is generally chosen where
; there may be hazards involved in using an electric initiation
system and electric blasting caps.
In the recent past many improvements have been made
in the quality and reliability of non-electric initiation
systems and in detonating fuse cord. Typical of such impro-
vement is that of Per-Anders Persson, ~hown in United States
patent No. 3,590,739, granted ~uly 6, 1971l which patent dis-
closes a detonating fuse which comprises a tube having only
a thin layer of a reactive substance coated on the inner area
thereof. Such a fuse is marketed under the registered trade
mark "Nonel". In United States patent No. 3,730,096, granted
May 1, 1973, Josef Prior discloses a very high detonation
velocity cord wherein the reactive explosive substance is
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placed between inner and outer concentric tubes. While
meritorious, these and similar improved cords nevertheless
raquire the use of sensitive explosive material in their
construction, the usa of which sensitive material involves
inherent hazard in manufacture and in use
It has now been found that detonation energy adequate
to initiate a conventional blasting cap or blasting relay can
be transmitted from an energy generator to the cap to be
initiated without the use of either conventional or modified
detonating or deflagrating cord. It has been surprisingly `
discovered that the energy from the explosive or deflagrative
initiation of a reactive substance can be transmitted through
substantial lengths of hollow, small diameter tubing which is
devoid of any explosive or reactive material content. The
detonation of a reactive substance confined within a generator
attached to one end of a length of, for example, small internal
diameter polyethylene or other plastic tubing, permits the
transmission through the tubing of sufficient explosive energy
to set off a conventional blasting cap attached at the opposite
end of the tubing. It is thus possible to initiate a non-
electric blasting cap from a remote source withou-t the use of
any explosive-containing detonating cord or fuse.
In order to bettex understand the invention,
referencP is made to the attached drawing wherein
Fig.lshows in cross-section a typical assembly
according to the invention comprising a generator, connecting
tubing and cap; and
Fig. 2 shows, also in cross-section, one means
for attaching an initiating means to the energy generator of
Fig. 1.
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The figures of the drawings are not to be construed
as a limitation of the invention.
Referring to Fig. 1, there is shown a typical non-
electric delay blasting cap 1 containing in sequence from the
closed end a kase explosive charge 2, a priming charge 3 and
an ignition or a delay element 4. A non-conductive channelled
closure plug 5 is shown crimped in place in the open end of
cap 1. The end of a length of hollow tubing 6 is held within
the channel of closure plug 5, the end of which tubing abutts
ignition or delay element 4. At the opposite end of tubing 6
is energy generator 7. In the embodiment depicted, generator
7 has the form of a blank ammunition cartridge and comprises
a metal shell 8 with a closed rim end 9 and an open end 10.
Within shell 8 at rim end 9 is a heat and impact sensitive
composition 11. In contact with composition 11 is a high
energy reactive substance 12. A destructable diaphragm or
membrane 13 i~ shown over the surface of substance 12.
A non-conductive channelled closure plug 14 is crimped in
position in the open end of shell 8. Closure plug 14 holds
within the channel the end of hollow tube 6 tightly against
membrane 13. Membrane 13 may be an integral part of closure
p~ug 14.
Referring to Fig. 2, there is shown the energy
generator 7 of Fig. 1 having around part of metal shell 8
and close to closed rim end 9, a slip-on or molded-on,
resiliant connector 15. Connector 15 can comprise, for
example, a hollow cylinder of plastic material adapted for
tight fit over shell 8. A protruding sleeve portion 16 of
connector 15 extends beyond rim end 9 and is notched in V-
shaped fashion to receive therein a cord-like initiator ~uch
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as, for exa~ple, a length of a low energy detonating cord
trunk line (not shown).
The impact and heat sensitive composition 11 within
shell 8 can be any such composition known to the explosive
art. For example, an ammunition primer composition comprising
a mixture of tetracene, lead styphnate, barium nitrate and
powdered glass has been found useful. Other suitable primer
composition mixtures are, for example (a) styphnate, tetracene,
barium nitrate, calcium silicide and lead peroxide; (b) lead
styphnate, tetracene, barium nitrate, aluminium powder and
antimony sulfide; (c) lead azide, antimony sulfide, potassium
chlorate and lead thiocyanate. The high energy reactive sub- ;
stance 12, in contact with composition 11 may be any one of
a number of single or mixed fast burning pyrotechnic or explo-
sive substances known to the art. Useful substances include,
for example smokeless powder, black powder, magnesium and
PE~ or mixtures of these.
In use in the field, an assembly compri~ing an
energy generator, a blasting cap and an interconnecting hollow
tube as shown in Fig. 1, and preferably pre-assembled in the
explosive factory, is selected wherein the length of the
interconnecting tube is appropriate for the blasting operation
to be undertaken. An initiating means for the energy gen rator,
for exampla, the end of a length of low energy detonating cord,
is secured or attached to the sensitive composition end of the
energy generator unit 7. Attachment may be accomplished by,
for example, use of the connector unit shown in Fig 2.
The cap end 1 of the assembly is placed in contact with an
explosive charge, for example, in a borehole or against a
boulder. Initiation of the low energy detonating cord from a
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remote location causes composition 11 and substance 12
within energy generator 7 to be ignited or detonated.
~ot gases and flash from this detonation are transmitted
via hollow tube 6 to initiate blasting cap 1 which, in
turn, detonates the associatad explosive charge. Where a
series of charges are to be detonated, a series of assemblies
may be connected at intervals along a single trunk line
length of detonating cord which, upon ignition, sets off
the attached energy generator and connected caps in a sequ-
; 10 ential manner.
The following Examples further illustrate the
present invention.
EXAMPLE 1
A series of tests were conducted wherein the energy
generator comprised a standard amm~nition primer composition
and a reactiv~ substance charge consisting of a 72 milligram
intermixture of smokeless powder/magnesium metal powder (70 -
80 mesh) in the mass ratio 46/54. The energy generators were
affixed to the ends of plastic tubes of various internal
diameters. At the free end of each assembly, standard fuse
blasting caps were attached. The blasting caps utilized had
an ignition charge of 60/40 lead azide/lead styphnate. The
maximum propagation distance, or the maximum tubing length
through which the generators would initiate a fuse blasting
cap, was measured. Results obtained are tabulated below in
Table I.
TABLE I
.
Tubing I.D.Maximum Propagation
(inches) Distance (inches)
0.138 72
0.090 60
0.070 42
0 049 27
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The results demonstrated that propagation distance
is related to the internal diameter of the tubing with a
constant size of charge of reactiva substance in the energy
generator,
ExAMæLE 2
The effect of assembly length on delay time and
average propagation velocity is demonstrated in TABLE II
below. In these tests, an intermixture of 77 milligrams
of smokeless powder and 65 milligrams of magnesium (70 -
80 mesh) served as the reactive substance charge. Each unitcompriqed a length of polypropylene/nylon tubing of dimensions
I.D. 0.138", O.D. 0.188", having a fuse blasting cap affixed
to one free end and a standard ammunition primer crimped to
the remaining free end.
TABLE II
Tubing Length Delay Time Average Propagation
(feet) (milliseconds) Velocity
(feet/second)
.
2 0.56 3571
~ 1.02 3g22
6 1.68 3571
8 ~.29 3494
3. 3a 2959
EXAMPLE 3
A reactive substance charge comprising a base layer
of 16 milligram~ of blackpowder and a top layer of 15 milli-
grams of PETN was utilized in the energy generator. The
generator and fuse hlasting caps were attached together by --~
lengths of polypropylene/nylon tubing of dimensions I.D.
0.138", 0,D, 0,188",
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Delay times hetween igrlition of the yenerator and
detonation of the cap using 4 feet and 5 feet lengths of
tubing wexe respectively 1.17 milliseconds and ~.58 milli-
seconds, thus indicating that a useful time-delay function
can be achieved by varying the length of the connecting tubing
EXAMPLE 4
A reactive substance charge in the energy generator
consisted oE a 132 mg intermixture of 68% granulated black-
powder and 32% magnesium metal powder, by weight. The generator
and fuse blasting caps were attached together by lengths of
"Surlyn" (Reg. Trade Mark) tubing of dimensions I.D. 0.090",
O.D. 0.155".
Delay times between ignition of the generator and
detonation of the cap using 4 and 5 feet lengths of tubing
were respectively 1.4~ and 1.89 milliseconds.
EXAMPLE 5
A reactive substance chl~rge in the energy generator
consisted o a 94 mil~igram intermixture of 59% smokeless
powder and 41% magnesium metal powder, by weight. The gene-
rators were crimped to 3 feet lengths of plastic tubing havingdimensions I.D. 0.138" and O.D. 0.188". Fuse blasting caps
were attached to the free end of each tubing assembly. The
delay times between ignition of the generator and detonatlon
of the cap of five such assemblies were measured. The mean
delay time and its associated standard deviation were 0.75
milliseconds and 0.12 milliseconds respectively.
EX~MPLE 6
The tests described in Example 5 were repeated with
identical energy genexator assemblies but with delay detonatoxs
affixed to the tubing. The delay detonators utilized were of
~- ` the short period vaxiety, containing a Pb30 /Si pyrotechnic
.
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delay element. The rated, or nominal, delay time and delay
time tolerance of these detonators were respectively 800
milliseconds and 731 to 869 milliseconds. Measurements of
the delay time between the ignition of the generator and
detonation of the delay cap of ten assemblies, each 3 feet
in length~ yielded a mean value of 829.5 milliseconds and
a delay time standard deviation of 8.1 milliseconds.
EXAMPLE 7
The tests described in Example 5 were repeated
but with a reactive substance charge within the energy
generator comprising an intimate mixture (83 mg) of smoke-
less powder and magnesium metal powder in the mass ratio
53/0/47% (S.P./Mg). The delay times of five assemblies,
each of length 3 feet, produced a mean value of 0.80 milli-
seconds and a delay time standard deviation of 0.07 milli-
seconds.
EXAMPLE 8
The tests described in I3xample 7 were repeated
with identical energy generators and type of tubing but in
this case, 4 feet lengths of tubing in conjunction with
delay detonators were utilized. The delay detonators employed
were of the same type as described in Example 5. Measurements
of the delay times of ten such assemblies yielded a mean delay
.,
time of 839.2 milliseconds and a delay time standard deviation
of 9.0 milliseconds.
It will be appreciated by knowledgeable workers
in the art that the components of the assembly will have to
be compatibly matched in order to insure the utility of the
system. For example, the means employed to initiate the
energy generator must not be so powerful as to cause destruction
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or tne g~nerator rather tnan its iniiiation lne quantiiy
and type of reactive substances employed in the generator
will have to be selected to produce the necessary heat and
flash effect to set off the attached blasting cap without
rupturing the conductive tubing. Similarly, the material
of construction, wall thickness, inside diameter and lenyth
of the tubing employed will be selected to retain the pres-
surized hot gases from the energy generator and transmit
therethrough sufficient energy to ignite the attached deto-
nator unit~ Further, the blasting cap or other explosivedevice for detcnation will necessarily be of a type susceptible
to initiation by the energy produced by the generator. Also,
khe means of connecting of both the generator and cap to the
tubing will have to be secure enough to maintain a pressure-
tight system.
The non-electric ignition assembly of the invention
provides important advantages over other non-electric systems
known from the prior art.
Since the connecting tubing does not rupture durin~
firing, an `explosive column in a borehole adjacent the tubing
cannot be prematurely detonated by lateral energy In ad-
dition, the great strength of the tubing also implies that
in the case of accidental initiation of hollow tube assemblies
during handling or transportation, the immediate environment
is exposed to minimum risk The tubing does not contain any
` reactive or explosive substancesand hence is insensitive to
-~ initiation by electro-magnetic effects such as stray electric
currents or static electricity~
The connecting tubing which preferably comprises
3a polyethylene, polypropylene, nylon, "Surlyn" (Reg TM) or
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combinations of these materials being devoid of any explosive
content results in a non-hazardous manufacturing operation
in comparison to conventional products.
Donald G, Ballantyne
Agent for Applicant
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