Note: Descriptions are shown in the official language in which they were submitted.
~ 9 7~8 Hopler Case 8
This invention relates to non-electri.c ~lasting caps
ini.tiated by the heat produced by the ignition of an explosive gas
mixture. In one aspect, this invention relates t~ non-electric
blasting caps Containing a porous ignition charge, initiatable
in response to action of explosive energy of an explosive ~as
mixture together with conduit means in contact with the porous
ignition charge for emplacing a confined stream of the explosive
gas in ignition position within the blasting cap for the respon-
sive initiation. A further aspect of this invention relates to
a detonator system, including a plurality of blasting caps above
de-scribed, together with means for emplacing an explosive gas
mixture in ignition relationship with a responsively initiatable
ignition charge~s) for the detonation of one or more main charges.
A sti.ll further aspect of this invention relates to methods for
making a porous ignition charge, making a non-electrically initi-
ated blasting cap and initiating a non-electrically ini.tiated
blasting cap for the initiation of a main charge. Other aspects
will be apparent in light of the accompanying disclosure and the
appended claims.
Non-electric blasting caps initiatable by explosive
energy from the detonation of an explosive gas mixture are dis-
closed and claimed in U.S. Patent No. 3,885,499 to Hurley. These
blasting caps contain an open space adjacent the ignition charge,
a first conduit extending from outside the blasting cap into the
open space in open communication with the ignition charge so as
to conveY the explosive gas as a confinea stream into the open
space for responsive ignition of the ignition charge and a sec-
ond conduit extending from the open space to the outsi.de of
the shell so that a stream of the explosive gas mixture can be
continuously passed from the first conduit through the open space
and through the second conduit to purge and charge the system for
the detonation and responsive ignition of the ignition charge.
In the embodiments illustrated in the above patent, the
cap shell is elongated and closed, including at one end a plug
- 2 -
1 ~9~7~ 8
type closure member spaced from the ignition charge to form the
requisite open space. Both conduits are p~astic and thin walled
for flexi~llity purposes.- The first conduit extenas into the
sh~ll through the end alosure member and the second conduit ex-
tends ~rom the open spaCe either through the plug end closure or
through the side of the cap shel~.
This invention is concerned with non-electric blasting
caps essentially of the type above described but ~hich do not
require an open spaCe between the ignition charge and the plug
closure member.
In accordance with the invention, a non-electrically
initiated blasting cap is provided which comprises: a closed
shell, including a plug closure therefor; an ignition charge in
said shell substantially contiguous with said plug closure and
initiatable in response to action of explosive energy of an ex-
plosive gas mixture, and sufficiently porous and permeable for
flow of a gas stream through the interstices thereof; a first con-
duit means extending from outside said shell through said plug
closure and opening into contiguous contact with said ignition
charge so as to convey an explosive gas mixture as a confined
stream into initiating position in said interstices for respon-
sive initiation of said ignition charge; and a second conduit
means extending from contiguous contact with said ignition charge
to the outside of said shell, whereby a stream of said explosive
gas can be continuously passed from said first conduit means
through the interstices of said ignition charge and through said
second conduit means to purge and charge said porous ignition
charge and thereafter explosive gas in said first conduit means
can be ignited for propagation of resulting explosive energy within
the interstices of said porous ignition charge for initiation of
same.
In a preferred embodiment, the closed shell is elongated,
having a base charge in the integrally closed end of the sh~ll,
a primer charge in direct operativ~ communication with the base
-- 3 --
~Q~97(~8
charge, a porous ig~ition charge in operative contact with the
primer charge, with or without a deIay charge intermediate the
primer and i~nition charges, wherein the plug closure substanti-
ally fills the cross-section of the 5hell and has a first and a
second passageway therethrough to allow gas to be introduced into
and to exit from the closed she~l. Further, and in preferred
practice, the porous ignition charge alone or together with a
delay charge substantially fills the cross-section of the closea
shell between the primer charge and the plug closure, has inter-
connnected pores and is initiatable in response to action ofexplosive energy of an explosive gas mixture, wherein, in turn,
the primer charae is detonatable in operative r~sponse to the
heat produced by the ig.nition charge or the ignition charge and
delay charge, and the base charge is detonatable in response to
the detonation of the primer charge, and wherein a delay charge
might be included intermediate to the primer and ignition charges,
said delay charge would be detonatable in operative response to
the heat produced by the ignition charge.
Further, in accordance with the invention, a detonator
system is provided for detonation of one or more main charges
comprising a plurality of spaced apart non-electrically initiated
blasting caps above described, wherein the first passageway of
the first of said plurality is connected with a source of explo-
sive gas mixture and means for igniting said explosive gas mix-
ture, and the second passageway of the first of said plurality is
connected with the first passageway of the second of said plurality
and thereby in series to provide for purging and charging action
of the porous ignition charge in each of said blasting caps by
flow of the explosive gas mixture in series flow therethrough
and subsequently f~r ignition of said explosive gas mixture to
propagate an explosive reaction front in series through each of
said blasting caps in said plurality. In addition, the invention
includes a method for making a porous i.gnition charge, a method
for making a blasting cap containing a porous ignition charge,
-- 4 --
l(t~971~8
and a method for initiating a non-eIectric blasting cap for the
initiation of a mai~ explosive charge.
The invention is illustrated with reference to the draw-
ings of which:
FIG. 1 illustrates a zero delay type blasting cap of
the invention, including a pair of conduits supported in an igni-
tion plug end clo~ure for ingress ana egress of the explosive gas
mixture during the purging and charging operation, and thereafter
for ingress o~ explosive energy from ignition of the explosive
gas mixture
FIG. 2 is a delay type blasting cap otherwise the same
as that of FIG. l;
FIG. 3 is the same as FIGS. 1 or 2 except that in lieu
of the egress conduit, an open passageway is disposed in the side
wall of the shell for egress of the explosive gas mixture during
the purging and charging operation;
FIG. 4 illustrates a plurality of any of the blasting
caps of Figs. 1 and 2 as elements of a detonator system of the
invention;
FIG. 5 is the same as FIG. 4 except that it illustrates
a plurality of blasting caps of FIG. 3;
FIG. 6 illustrates an embodiment of the blasting system
of the invention including a plurality of blasting caps of either
or both of FIGS. 1 and 2 supported for detonation of a series of
separate main explosive charges. Like parts in the drawings are
designated by like numbers.
FIGS. 4-6 are particularly illustrative of the method
for initiating non-electric blasting caps for the initiation of
main explosive charges.
Referring to FIG. 1, elongated cup-shaped shell lQ of
zero delay type blasting cap g is integrally closed at bottom
end 11 and is closed at the opposite end 12 by ;gnition plug end
closure 13. Base explosive charge 14, primer charge 1~ and porous
ignition charge 17 extend in that order in shell 10 from bottom
-- 5 --
1(~897(~8
end 11 toward closure plug 13, and face 18 of porous ignition charge 17
is in substantial contiguous contact with face 13' of plug 13. Although
charge 17 can be referred to as an initiator or ignition charge, herein-
after, it will be described as porous ignition charge 17.
A first tube 19 extends from outside shell 10 through plug
closure 13 into communication with por~us ignition charge 17. A second
tube 21 extends through plug 13 from a point in communication with porous
ignition charge 17 to a point outside shell 10.
Base charge 14 is detonatable in response to detonation of
primer charge 16 and primer charge 16 is detonatable in response to the
heat output of porous ignition charge 17. Base charge 14 is any suitable
high explosive charge such as PETN, RDX, Tetryl, OT the like, with adequate
explosive energy output to produce detonation of a main explosive charge
in detonating relationship therewith. Exemplary of primer charge 16 is
diazodinitrophenol, often a diazodinitrophenol system of the wèll known
type incluting a top layer for ignition in response to ignition of the
pOI0uS ignition charge 17 and an underlying higher_density layer detonat-
able in response to ignition of the top layer. Further exemplary primer
chasges 16 are tiazotinitrophenol/potassium chlorate, lead azide, mercuTy
~ulminate, leat styphnate, barium styphnate, potassium dinitrobenzfuroxyl
and nannitol hexanitrate tetracene.
POTOUS ignition charge 17 may be a pOTOUS agglomeration of
; partîcles made from an ignition powder; a permeable mat-like pad of fibrous
particles of ignition ~aterial; a pellet of minute spheres of ignition
material, attachet to one another at their contact surfaces, preferably
; by coating with a binder material, to prevent transport of the spheres
into the gas conduits during charging or handling; or a sponge-like
pellet of ignition material, with connected porosity to protuce pe$me
ability. Porous ignition charge 17 must be pe~eable for flow of a gas
stream therethrough, preferably it shoult have an effective cross-sectional
~6~
~,'
-
1(~897(~8
area ~o~ gas flow at least substantially equal to the cross-sectional area
said irst or second condduit means~ Porous ignition charge 17 must
also be initiatable in response to action of explosive energy of an
explosive gas mixture. Examples of materials which can be used for porous
ignition charge 17 are
-6a-
B
97U8
lead/selenium, lead-tin/selenium, tin/selenium, red lead/boron,
lead monoxide/boron, lead oxide/manganese, lead monoxide/silicon,
and lead/tel~urium
By the term "explosive energy" is meant the heat and
flame produced by the detonation or deflagration of an explosive
gas mixture~ -
Tube 19 is generally a plastic tube, as for example,0.103 inch OD by 0.0~0 inch ID and formed from polyethylene; and
confines a stream of the explosive gas mixture for flow into
porous ignition charge 17, and tube 21 is the same, or similar
in design and composition to tube 19. Tube 21, in direct contact
with porous ignition charge 17, serves to convey a stream of ex-
plosive gas mi~ture from porous ignition charge 17, during the
purging and charging operation and, as an element of the initia-
tion system of the invention, to direct propagating explosive
energy to the succeeding blasting cap in the system.
In the operation of blasting cap assembly 9, a stream
of an explosive gas mixture such as a mixture of oxygen with a
fuel such as manufactured gas, acetylene, hydrogen, or hydrogen/
methane, is passed through tube 19 into porous ignition charge
17 and is thus emplaced so that, upon ignition, the resulting
explosive energy propagates into initiation relationship wïth
porous ignition charge 17~ Prior to initiation of porous igni-
tion charge 17, enough of the gas, which is initially present in
the interconnected pores of charge 17, must be replaced by the
explosive gas mixture from tube 19 to insure reliable initiation.
This is accomplished by passing a stream of the explosive gas
through tube 19, porous ignltion charge 17 and then tube 21 to
purge the pores of charge 17 free from such initially present
gas.
FIG. 2 illustrates another embodiment, which is the same
as that of FIG. 1 except that the blasting cap 9' is of the delay
type and contains a delay charge 22 intermediate the porous igni-
tion charge 17 and primer ch~rge 16. Often p~rous ignïtion charge
-- 7 --
~ (?i~'37(~8
17 of FIG, 2 dif~ers in composition from that of FIG. 1 to the
extent necessary to a~sure a sufficiently hot ignition for delay
fuse 23, which is conventionally disposea as a core in a swaged
metal tube 24 in ignitable relationship with porous ignition
charge 17 and in detonating relationship with primer 16. Often,
in a delay cap system such as that of FIG. 2, a wafer type charge
(not specifically shown) which has a higher heat of reaction than
that of porous ignition charge ~7 and serves as a supplemental
source of heat for ignition of the delay fuse, is positioned sub-
jacent porous ignition charge 17. Such wafer type charges aregenerally utilized in combination with longer burning and hence
less ignition-sensitive delay charges, as disclosed in U.S.
Patent No. 3,776,135.
FIG. 3 illustrates a blasting cap 8 which is similar to
the blasting caps of FIGS. 1 and 2 except that in lieu of the tube
21, a conduit or passageway 26, extends from open communication
with porous ignition charge 17 through a side wall of shell 10.
Referring to FIG. 4, a series of five blasting caps A-E
inclusive, which can be any of blasting caps 9 and 9' of FIGS. 1
and 2, each for being disposed in detonating relationship with a
booster or main explosive charge (neither shown), are in series
with the discharge line fro~ a gas mixing and ignition system 27.
Gas mixing and ignition system 27 comprises fuel gas supply 28,
connecting through line 29, gas flow control meter 31, and line
30, with gas mixing/ignition chamber 32 and oxidizer gas supply
33, connecting through line 34, flow control meter 36, and line 37
with gas mixing/ignition chamber 32.
In operation of the system 27, a suitable fuel gas, gen-
erally a manufactured gas, or a mixture of hydrogen and methane,
is passed from supply 28 via line 29, through flow meter 31 which
in turn controls the requisite rate of flow and pressure of fuel
gas through line 30 to mixing chamber 32 for mixing therein with
oxidizer gas from supply 33. Similarly th~ oxidizing gas is passed
from supply 33 via line 34, through flow meter 36 wl~ich in turn
-- 8 --
1~389'7~
controls the requisite rate of flow and pressure of oxidizer gas
through line 37 in the r~quirea proportions for the mixing step
in chamber 32. The ~ela~ive proportions of fuel and oxidizer are
predetermined to pro~ide an explosive gas mixture which is then
ignited in chamber 32 by a spark generated by action of spark plug
39 operativëly extending into chamber 32 for that purpose.
Conduit 38 extends from chamber 32 and connects through
a suitable collar, or sleeve-type connector 38a with inlet tube
19 of a first blasting cap 9 of the series A-E to convey flow of
the explosive gas mixture from chamber 32 through the tube member
19, porous ignition charge 17 and exit flow tube 21, and in series
through each of the successive caps B-E to thereby purge each
p~rous ignition charge ~7 of substantially all gas other than that
from line 38 and in turn to charge each porous ignition charge 17
with the explosive gas mixture. Tube 21 of each of blasting caps
4A-D connects with tube 19 of the succeeding blasting cap of the
Series B-E by any suitable means, such as by a plastic collar, or
sleeve, connector 20,
During the purging and charging operation, the stream
of explosive gas mixture from line 38 is passed in series through
tube 19, porous ignition charge 17 and tube 21 of each of caps
A-E; and the flow o explosiv~ gas through the series A-E is main-
tained for a time duration sufficient to complete the requisite
purging and charging of all blasting cap ignition charges 17, gen-
erally for a period of at least about one minute, but often from
five to ten minutes, depending upon the flow variables involved.
Upon completion of the purging and charging action and
with the flow of the explosive gas mixture in line 38 stopped,
the ignitor member 39 is actuat~d, and, by action of the spark,
the explosive gas mixture thus smplaced for i~nition and respon-
sive initiatioh of the porous ignition charge, is ignited. Check
valve syst~m 35 in chamber 32 precludes back pressure flow of
explosive energy into the upstream flow and supply stream. The
explosive reaction wave front then travels, confined in line 38
_ g _
97~8
and each of tubes 19 and ~1, through eaah poroug lgnition charge
17 in series A-E.
Occasionally, one'or more of the tubes 19 and 21 may
fail to confine the explosive energy, in which ~vent the reaction
rate of the particular explosive gas is sufficiently hig~ to per-
mit the explosive reaction wave front to travel ahead of the tube
breakage so that the latter does not preclude series travel of
the wave front through the series of caps.
FIG. S illustrates another embodiment of the detonator
system of the invention which is the same as that in FIG. 4 except
that blasting caps 8 of FIG. 3 are in lieu of those of FIGS. 1
or 2. In the embodimsnt of FIG. 5, a continuous stream of an
explosive gas mixture from chamber 32 is passed through line 38
as a manifold supply connecting by suitable connector means, such
as a collar or sleeve ~S, with each of the caps A-E respectively
to supply a stream of explosive gas mixture through each tube 19
into each corresponding porous ignition charge 17A-E. InGtead
of the series type purging and charging action of FIG. 4, the
explosive gas mixture from each porous ignition charge 17 is dis-
charged therefrom through the conduit, or opening, 26 in a sidewall of each cap assembly. As in FIG. 4, after the requisite'
purging and charging period, the explosive gas mixture in line 38
is ignited by action of spark generation means in chamber 32.
The explosive reaction wave front then travels along line'38
through each tube 19, to, in each instance, emplace the'resulting
explosive energy in initiating contact with the ignition charge.
Referring to FIG. ~, each of the separate bore holes 41,
in earth formation 40, of FIGS. 6A-C is loaded with any suitable
cap-insensitive main exp~esive charge 4~ such as an aqueous gel
type explosive, prills/fuel oi~, or the'like. A pair of suita~le
boosters 43 is embedd~d i~ each of the màin explosive masses.
Each booster is ~ap-sensitive and is in detonating reIationship
with main explosive aharge'42 adjacent thereto, and ïs initiatea
-- 10 --
le~s7us
by action of a blasting cap system of the invention such as that
of FIG~ 4.
Thus in each b~re ho~e 41 of FIG. 6, two booster units
43, e.g., each 500 grams of PE~N, tetryl ox the like are embedded
and spaced apart, in main explosive Gharge 42 to provide for det-
onation of the main explosive charge 42 along its entire length.
Each hooster unit 4~ contains a blasting cap 9 or 9' of FIGS. 1
or 2, respectively. The explosive gas mixture from chamber 32
(not shown) is supplied via line 38 and passed in series through
the entire plurality of blasting caps 9 and/or 9' in the separate
booster charges in the three bore holes via tubes 19 and 21 of each
blasting cap, as illustrated with r~erence to FIG. 4. The flow
of explosive gas mixture rom line 38 in series through the en-
- tire plurality of blasting caps in the bore holes 41A-C is con-
tinued until each porous ignition charge 17 is substantially
free from initially present gas, ater which the ~low of the ex-
plosive gas mixture stream is terminated or continued as desired,
followed by ignition of the gas in chamber 32 and travel of the
explosive reaction wave front in series through each of the blast-
ing caps in initiation relationship with the main explosive chargetherein. Dependent on whether a main charge is reliably cap-
sensitive~ a booster charge(s) may not be required, in which
event one or more of the blasting caps are embedded directly in
the main charge, and are charged with gas and initiated.
The system of FIG. 6 containing delay caps regulates
the burning time of each delay charge and hence, the delay between
shots in each bore hole including, when desired, a progressively
longer delay time along the entire series of boosters in the bore
holes of FIG. 6.
3~ Although the invention is specifically illustrated with
reference to delay and nondelay type blasting caps utilizing a
porous ignition charge in combination with primer and base charges,
with or without an intermediate delay charge, it is to be under-
stood that the invention is applicable to initiation devices in
-- 11 --
1(~l3~7Q8
Which the ignition charge is the only charge in the device, or
is utili~ed with o~e or more additional charges, exemplary of
which initiating devices are those of the deflagrating or squib
type.
A non-e~ectric b~asting cap 9 containing a porous
ignition charge, as shown in FIG. 1, is made by initially pro-
viding ~longated cup-shaped shell 10 which is integrally closed
at bottom end 11~ Base explosive charge 14 and primer charge 16
are placed in the shell 10, with base explosive charge 14 in
contact with the inner surface of bottom end 11 and primer charge
16 resting thereon. Where a delay type, non-electric blasting
cap with porous ignition charge is desired, as shown in FIG. 2,
the delay charge or fuse assembly 22 is placed in shell 10 upon
and in contact with primer charge 16. The porous ignition charge
17 may be prepared by initially forming a suitable ighition powder
into a pellet, i~e., by pressing the powder within a cylindrical
press mold, with sufficient pressure to consolidate the ignition
powder. The compressed pellet is then removed from the press
mold and cut into small fragments. These fragments are then
screened to provide a predetermined size range, free of fine par-
ticles and dust, preferably with a maximum cross-sectiona~ dimen-
sion less tha~ about 0.187 inch, fo~ flow of a fluid therethrough.
The fragments are then placed in shell 10, thereby having a por-
tion thereof in direct contact with primer charge 16 or delay charge
22, if present. The charge fragments are placed in shell 10 to a
predetermined height, after which, ignition plug end closure 13,
containing tubes 19 and 21, is forced into shell 10 through end
12 until contact is made by face 13' of plug 13 with face 18 of
porous ignition charge 17. A standardized fluid flow test is
then made on each cap to detect any leakage or blockage of the
passageways within th~ cap.
Exa~le
Six non-electric b~asting caps containing porous ignition
ch~rges were made in accordancQ with the method of this invention.
- 12 -
7(~8
These six blasting caps were of the delay type containing a base
charge, primer charge, de~ay charge and porous ignition charge
as shown in FIG, 2. Each cap was made with a cylindrical aluminum
shell having a lehgth of 2~01 in., an I.D. of from 0 249 in. to
0.256 in. and ~n O.D. of 0.288 in. A base charge 14, which con-
sisted of PETN weighing 0.4 gm., was placed through end 12 into
shell 10 in contact with the inher ace of bottom end 11. The
PETN was placed in the shell as a loose powder and then pressed
in the shell. The primer aharge 16 consisted of a cylindrical
pelle~ of dia~odinitrophenol, weighing 0.29 gm., and was placed
through end 12 onto and in contact with base charge 14. The com-
bined height of base charge 14 and primer charge 16 was approx-
imately 0.9 in. The delay charge 22 consisted of a 2 gm. pressed
cylindrical pellet of, ~weight basis), lead, 46.9%, tin, 8.3%,
selenium, 11.6%, lead oxide, 32.2%, and boron, 1.0~, having a
length of 0.4 in. This pellet, designed to provide a delay time
of 300-400 milliseconds, was placed through end 12 into cap 10
upon and in contact with primer charge 16, to provide a combined
base, primer, and delay charge height of 1.3". The porous igni-
tion charge 17 was prepared from an ignition powder consistingof (weight basis) lead, 68.4~, selenium, 26.6%, potassium per-
chlorate, 2.2%, aluminum, 1.1%, and snow floss, 1.7%. The igni-
tion powder was ~ormed into a .250 in. O.D. 0.25 in. pellet by
placing the powder into a cylindrical mold and subjecting said
powder to a pressure of 3000 p.s.i. The pellet was then cut with
a razor blade into small irregular fragments. The desired size
range was obtained by retrieving the fragments which passed
through a #4 sieve (U.S.S.S.) and were retained on a ~8 sieve
(U.S.S.S.). The fragments were then loosely placed in shell 10
to a total column height of approximatel~ 1.8 ih. for each cap.
The alosure plug assembly 13, which was 0.45 in. long, was then
forced into shell ~0 until contact was made by inner face 13' of
plug assem~l~ 13 with outer face 18 of porous ignition charge 17.
Closure plug assemb~y 13 contained two 12 in. long tubes 19 and
- 13 -
~ 9708
21 made of low density polyethylene and having an 0.103 in. O.D.
and 0.060 in. I.D., whiah were bonded to plug a8semb1y 13 and had
terminal ends 19', within the passageways of plug assembly 13,
whioh were in aontact with porous ignition aharge 17. The plug
assembly 13 was then affixed to the sheIl 10 by crimping shell 10
around its extQrior along the portion adjacQnt to plug assembly
~ 13.
.: .~
A test for circuit continuity was then separately
performed on each of the six caps by passing nitrogen gas at 50
p.s.i.g. through tu~e 19, and measuring the exit flow from tube
21.
~ A stream of gas, comprising, on a volume basis, 50%
; methane and 50% hydrogen, at an approximate rate of 25 liters
(S.T.P.) per minute at 40 p.s.i.g., was mixed with a separate
stream of oxygen at a rate of 59 liters (S.T.P.~ per minute at
4Q p.s.i.g. through 10 feet of 0.25 in. O.D. by 0.120 in. I.D.
polyethylene tubing to form an explosive gas mixture as the com-
bined stream. The oxygen con~tituted approximately 71% of the
; combined stream, which was passed through each individual cap for
approximately 0.2~ minute to pUrge and charge the tubing circuit,
including porous ignition charge 17, thereby replacing the air
which originally filled the tubing circuit, with the explosive
gas mixture. After charging, the resulting explosive gas mixture
was in each instance ignited upstream rom the individual caps
by a spark, whereupon the explosive energy associated with the
detonation front, which passed through tube 19 and into porous
ignition cha~ge 17, initiated each ignition charge. Each of the
six caps fired successfully.
As wiil be evident to those skilled in the art, various
modifications can be made in the ~ight of the foregoing disclosure
and disc~ssion, without departing from the spirit or scope of the
disclosure or from the scop~ of the claims.
- 14 -
