FORM 2
THE PATENTS ACT 1970
(39 of 1970)
&
The Patents Rules, 2003
COMPLETE SPECIFICATION
(See section 10 and rule 13)
1. THERMAL SPARK CONDUCTOR TUBE USING NANOMETRIC PARTICLES
2.
1. (A) PARI SA
(B) Switzerland
(C) Bahnhofstrasse 7, CH-6301 Zug, Switzerland
The following specification particularly describes the invention and the manner in which it is to be
performed.
2
[01] The present Invention Patent refers to a thermal
spark conductor tube, applied as a signal transmitter for connection and initiation
of explosive columns, usually complemented by a delay fuze or used as a delay
unit, which employs a low toxicity nanometric pyrotechnic mixture with the
superior thermal performance of the spark, which maintains the advantages of the
current pyrotechnic shock tube in relation to the shock wave conduction tube, that
is, product with greater sensitivity and sensibility of transmission, maintenance of
propagation even with cuts or holes in the tube, and low risk classification in the
tube transport and process with the possibility of continuous and separate dosing
of the non-activated components, simultaneously with the formation of the plastic
tube and presents additional advantages of reduction or even elimination of the use
of contaminants from underground water, present a lower risk of ignition by
electrostatic discharge of the human body, and to use the production process of the
pyrotechnic mixture quite simple and with a lower risk of accidents due to friction
and mechanical shocks.
[02] Since the early 1980s, signal transmitting tubes,
commercially known as "non-electric detonators" or "shock tubes", have been
widely applied for connection and initiation of explosives in the building area, and
marketed with such brands as NONEL, EXEL, BRINEL, etc. Such devices are
applied to replace the electric fuzes connected through metallic wires in most
applications, representing a revolution in the area of detonation accessories, either
by their ease of connection and application, or by the intrinsic safety against
accidental ignitions by induction of spurious electric current.
[03] Currently there are the following main processes
for the production of these devices and resulting products:
[04] 1) U.S. Patent No. 3,590,739 is the original
reference of the conventional shock tube. Describes a plastic extrusion process
forming an outer diameter circular tube ranging from 2.0 to 6.0 mm and internal
3
diameter ranging from 1.0 to 5.0 mm, where secondary explosive powder is
introduced continuously and simultaneously such as HMX, RDX or PETN,
previously mixed with Aluminum Powder, at its inner periphery, at the same time
as the tube is formed, resulting in a product called a non-electric shock tube,
commercially available under such trade names as NONEL and EXEL, which,
when initiated by a primary explosive blasting cap, generates a gaseous shock and
impact wave with speeds of 1,800 to 2,200 m/s;
[05] 2) Brazilian patent BR 8104552, is the original
reference of the pyrotechnic shock tube. It describes a plastic extrusion process
forming an outer diameter circular tube ranging from 2.0 to 6.0 mm and internal
diameter ranging from 1.0 to 5.0 mm, where is continuously and concomitantly
introduced K2Cr2O7 + Al or Mg , orFe2O3 + Al or Mg, orSb2O3+ Al or Mg, Sb2O5
+ Al or Mg orO2 + Al or Mg pyrotechnic mixture powder, at its internal periphery,
at the same time that the tube is formed, obtaining a product called pyrotechnic
non-electric shock tube, which when initiated by a primary explosive fuze, reacts
by aluminothermy without generation of gases, and generates a plasma of energy
conduction;
[06] 3) U.S. Patent No. 4,757,764 describes a nonelectric
system for disassemble initiation signal control using plastic tube with
delay pyrotechnic blends adhered in its interior, in particular using low speed
deflagration, i.e. at speeds much smaller than those of conventional shock tubes
and detonating cord, in order to use predetermined tube lengths to obtain a fast
delay time, in the order of milliseconds, instead of the conventional delay
element.In order to present this concept, the fuzes used are necessarily
instantaneous, without delay element, and there was no concern of the inventor in
optimizing the thermal performance of the spark, in ensuring the passage through
constraints in the tube, or in decreasing the Sensitivity to friction and shock of the
blend. It is clear from the patent specification report, and from all examples, that
4
its use as a delay element is limited to the tens of milliseconds range and is not
suitable for most of the delays practically used.
[07] Signal transmission tubes are usually
complemented by the insertion of a delay fuze at its end, consisting of a metal
capsule containing a layer of secondary explosive pressed in its interior, followed
by a layer of primary explosive, and a delay element comprised of a metal cylinder
containing therein a compacted powder delay pyrotechnic mixture column and
often an additional column of initiating pyrotechnic mixture that is sensitive to the
heat generated by the percussion and impact wave.
[08] The wave and percussion conduction tube
manufacturing process has the following disadvantages:
[09] a) The manufacture of explosive-loaded tube
(RDX or PETNare toxic and dangerous) offers risks of both accidental explosions
and handling of toxic products, requiring special care and special protections in the
manufacturing line. The fact of using molecular explosive prevents the dosing of
non-activated components during tube extrusion;
[010] b) In the conventional shock wave conduction
tube, the reaction products generated are basically hot gases, which, upon exiting
the opposite end of the tube, undergo expansion with heat loss, which hinders the
initiation of delayed pyrotechnic mixtures, it being necessary either to add a
sensitive pyrotechnic mixture column to give continuity to the explosive train or to
use pyrotechnic mixtures which are more sensitive to heat and with a longer
length. As a consequence, there is a product with higher cost of manufacturing and
use, besides offering greater risks in the manufacturing;
[011] c) The adherence of crystalline explosives, RDX
or PETN in plastic tubes is low, requiring the use of special processes of
manufacture and use of special plastic resins, usually ionomeric polymers such as
Surlyn, to minimize the presence of unbound powder and avoid unloaded portions
of the tube;
5
[012] d) The conventional shock wave conduction tube
has a low Sensitivity of energy transmission through a space between two portions
of the air gap aligned tube, generally smaller than 1 cm, so that any cuts or holes in
the tube cause use failures due to loss of shock wave pressure;
[013] e) The conventional shock wave conduction tube
exhibits sensibility to the so-called “snap, slap, and shoot” effect by the industry,
and accidental ignition may occur when the tube is pulled and ruptured, as
recognized in the paper presented in 28th. ISEE Annual Conference, Las Vegas,
2002, and in all catalogs and manuals for use of conventional shock tubes.
[014] f) Conventional shock tube is classified as an
explosive for transport in many countries, resulting in additional costs and
difficulties for transport, especially after increasing the strictness of inspection of
dangerous products due to the fight against terrorism;
[015] g) The conventional shock tube exhibits failures
after exposure to water at pressures above 2 bar, which often occurs in the
application of explosives, due to the hydrophilic characteristics of the Surlyn type
ionomeric resins;
[016] h) Tubes made of Surlyn type resins have low
bursting tensions and high permeability of hydrocarbons present in hot explosive
emulsions, which forces the co-extrusion of an additional outer layer of
polyethylene;
[017] i) The ionomeric resins represent a high cost
compared to more common resins, such as polyethylene;
[018] j) The tube deflagration speeds ranging from
1800 to 2200 m/s, according to the manufacturer's specifications, I,e. +/- 10%
around the average speed, which interferes with the accuracy of the delay element.
For example, both U.S. patents 5,173,569, 5,435,248, 5,942,718, and Brazilian BR
9502995, use a shock tube as an electronic delay fuze initiator. These fuzes are
characterized by a high precision electronic delay element, however the delay time
6
error of a given length of tube is incorporated to the error intrinsic to the electronic
circuit. At a typical length of 21 m, used in open pit detonations, the error would
be +/- 1 ms, while the intrinsic accuracy of the electronic circuits is typically +/-
0.1 ms; and
[019] k) The conventional shock tube, by generating
basically gaseous reaction products producing a percussion and impact wave,
disperses much of the thermal energy generated in the expansion of these gases as
it leaves the tip of the tube, so that it can only initiate delay elements that are very
heat sensitive, requiring additional sensitive ignition elements on the slow delay
elements, increasing the risks and costs of the industrial process;
[020] The pyrotechnic shock tube has the following
disadvantages:
[021] A) Pyrotechnic mixtures use K2Cr2O7, Sb2O3 and
Sb2O5 toxic products and flammable solvents, requiring solvent recycling,
handling care and proper disposal of wastes;
[022] B) The extrusion process of the plastic tube
involves the dosage of the previously prepared sensitive pyrotechnic mixture,
during the formation of the plastic tube, with risks of accidental initiation and
propagation to the rest of the mixture;
[023] C) The pyrotechnic shock tube does not withstand
the chemical attack of the hydrocarbons used in the hot explosive emulsion
formulations, which are the most frequently encountered environment in the civil
explosive applications currently, occurring faults in the continuity of the spark
after this attack;
[024] D) The mixture of O2 + Al or Mg provided in the
patent for the pyrotechnic shock tube was not feasible in practice due to the loss of
gases in the manufacture and use of the product
[025] E) The mixture of Fe2O3 + Al or Mg, provided in
the patent for the pyrotechnic shock tube, was not feasible in practice, due to the
7
low sensibility of the pyrotechnic mixture to the ignition stimuli found in the
application in electric fuzes or ignitors and high index of continuity failures, which
is due to the high temperature of Tammann of the components;
[026] F) Due to the limitations given in items D and E,
the only remaining options employ highly toxic substances K2Cr2O7, Sb2O3 and
Sb2O5 and mixtures sensitive to friction and shock;
[027] G) The reaction products formed in the reactions
of aluminothermy, Al2O3, K2O, Sb, antimony oxides, Cr2O3, obligatorily solid by
the limitations of the patent have low thermal conductivity, which makes difficult
the ignition of poorly sensitive delay elements;
[028] H) The solid reaction products formed in the
aluminothermy reactions, obligatorily solids due to the limitations of the Al2O3,
K2O, Sb, antimony oxides, Cr2O3, have low thermal conductivity, which makes
difficult the ignition of poorly sensitive delay elements ; and
[029] I) The powdered pyrotechnic mixture shows poor
adherence to the plastic of the tube.
[030] The non-electric system for disassemble initiation
signal control of U.S. Patent 4,757,764 has the following disadvantages:
[031] Aa) The extrusion process of the plastic tube
involves the dosage of the previously prepared sensitive pyrotechnic mixture
during the formation of the plastic tube, with risks of accidental initiation and
spreading to the rest of the mixture;
[032] Bb) The system, by using direct tube-to-tube
connections, providing a time delay exclusively over a given tube length, is
limited to short delays, up to the range of tens of milliseconds, while applications
require delays up to the range of seconds, typically up to 10 s;
[033] Cc) The powdered mixtures, containing no
adhesion-promoting additive, exhibit low adherence to the plastic of the tube,
8
requiring to use as tube material a Surlyn® type ionomeric resin or silicone as
observed in all examples; and
[034] Dd) Since the aim of the author was to obtain a
delay system through a tube with substantially reduced speed by eliminating the
delay element from the interior of the capsule, there was no optimization of the
thermal performance of the formulations. Thus, mixtures with low speed do not
initiate slow delays directly.
[035] More recently, a major technological advance has
emerged in Brazilian patent BR0303546-8, which is based on the combination of
substances in which a developed high-energy pyrotechnic reaction (Al + Fe3O4, for
example) generates molten metal spark with high heat transfer by conduction and
convection for the medium to be started. However, it requires a third low
temperature substance of Tammann [TTammann = Tfusion/2], with temperatures
expressed in absolute units, that is, with a scale where the zero point coincides
with absolute zero, such as K (Kelvin) or R (Rankine) to provide a sufficiently low
activation energy for both the tube ignition and the propagation of the spark under
critical conditions, for example in the case of diesel oil entering the tube.
[036] Although it was a great technological advance,
the inventor researched new solutions using the industrial expertise currently
available, solving the disadvantages, limitations and inconveniences of reducing or
even eliminating the use of contaminants from underground water, presenting a
great risk to conduct an electrostatic discharge from the human body to its end,
and to use pyrotechnic mixture production process quite complex and with risks of
accidents due to friction and mechanical shocks.
[037] "THERMAL SPARK CONDUCTOR TUBE
WITH USE OF NANOMETRIC PARTICLES", object of the present patent was
developed to overcome the disadvantages, drawbacks and limitations of the
existing tubes, as it can eliminate the substance with low temperature of
Tammann, even though the activation energy remains high, by the use of particles
9
of nanometric diameter, which surprisingly allowed to ignite by the usual means
and propagation of the spark through the tube, even under critical conditions of
use, thereby allowing the elimination of substances which give the mixture a
greater sensitivity to friction and shock, and which are often prohibited by
government regulations of several countries, especially perchlorates, which have
been eliminated in formulations of explosives in the USA. In addition,
perchlorates are salts that readily ionize when exposed to moisture, even moisture
remaining in the atmospheric air inside the tube, and for this reason contribute to
an inadequate result in the flash-over test EN-13763-12 of the European Union.
[038] Additionally, it uses aluminum particles coated
with electrically insulating layers of silica or aluminum oxide, so that such
particles do not conduct static electricity through the interior of the tube.
[039] The present invention solved the following
problems that the solutions of the technical state-of-art did not solve:
[040] 1. The low temperature substances of Tammann
which actually functioned commercially for the product of the prior invention
were inorganic perchlorates, notably potassium perchlorate, which has been the
subject of regulatory bans in a number of countries, such as the USA and
European Union, because perchlorates contaminate water sources, which can
cause methemoglobinemy and hyperthyroidism by eliminating iodine. The main
target has been explosives based on inorganic perchlorates, especially explosive
emulsions for use in underground mines, which have sodium, ammonium or
potassium perchlorate in their formulations;
[041] 2. The very characteristic of low activation
energy of low temperature compounds provides a higher sensitivity to the friction
and shock in pyrotechnic mixtures containing such substances, increasing the risk
of accidents;
[042] 3. Sodium and potassium perchlorates are also in
the form of crystalline salts of very large particle mean diameter for direct
10
application to the spark-generating mixtures of the prior invention (mean diameter
greater than 40 μm), so that a prior micronization (particle size reduction)
operation is required in micronizers by mechanical shock of compressed air jets, in
multiple costly steps in both price and power consumption, until a mean particle
diameter of 1.5 μm or less is obtained; and
[043] 4. The negative (inadequate) result in the flashover
test, ie the specific test of the European Union which requires that the
pyrotechnic mixture when disposed in final form inside the tube does not increase
the breaking distance of the dielectric resistance of the atmospheric air of this
same interior. Such a requirement is due to the risk that an electrostatic discharge
of the level of energy normally accumulated in the human body occurs at the
opposite end of a tube which has come into contact with an electrostatically
charged individual, which may initiate a fuze connected to this tube. In other
words, the pyrotechnic mixture must have a low electrical conductivity. However,
both aluminum and ionic potassium perchlorate are good conductors of electricity.
[044] In the present invention, these problems have
been solved by using only two non-forbidden components (aluminum and iron
oxide or copper oxide in particle diameters of the order of nanometers), and which,
due to Tammann temperatures higher than perchlorate, present higher activation
energy and make their pyrotechnic mixtures less sensitive to friction and
mechanical shocks.
[045] The aluminum of the present invention is in the
electrically insulating form because its particles are coated by a hard layer
(mechanically resistant) of silica (silicon oxide) or electrically insulating
aluminum oxide. Potassium perchlorate has been eliminated or substantially
reduced in the present invention because even low moisture of the air is sufficient
to make pyrotechnic mixtures containing readily electrically conductive ionizable
salts to the extent of being disapproved in the flash-over test. The use of the
11
minimum amounts of perchlorate applies mainly in some applications where
passage through folds or knots may occur.
[046] The object of the present patent has the
advantages of dispensing with the use of low temperature substance of Tammann,
therefore the pyrotechnic mixture inside it, is less sensitive to friction and shock,
dispenses the use or allows substantial reduction of perchlorate contaminants from
underground water, it is approved for the flash-over test, ie it has a lower risk of
conducting an electrostatic discharge from the human body to its end, and the
production process of the pyrotechnic mixture is quite simple by simply mixing
the components in an elastic polymer ball mill.
[047] Several tests were carried out to determine the
percentage ranges of the components, following the name and detailed description
of each of them:
[048] 1)“Flash-over” test
[049] This test is performed on flash-over equipment
according to European Standard EN 13763-24: Explosives for Civil Use -
Detonators and Transmitters - Part 24: Determination of the electrical nonconductivity
of the shock tube. The test is briefly described below:
[050] Thirty samples of spark conductor tube of 100
mm length are used in the test, which consists of traversing two thin rod-shaped
electrodes, one at each end of the sample, perfectly aligned with the center of the
tube, applying a voltage of 10 kV in direct current between the electrodes, and
approach its tips slowly until the passage of a spark between them occurs. The
distance in millimeters in which 5) the greater the more electrically conductive the
tube inner medium, the greater the risk of conducting an electrostatic discharge
from the human body into the tube inner. The specification limit of the European
Standard is a maximum of 20 mm.
[051] 2) Propagation Speed Test
12
[052] A length of tube measuring 5 m in length is
placed between two optical sensors connected to a precision timer. When the tube
is started, the light of the spark, when passing the first sensor, starts counting time,
and, when it passes the second sensor, stops this count. The propagation speed is
obtained by dividing 5 by the time obtained in seconds.
[053] 3) Test of Minimum Space of Propagation
Between Folds
[054] In 10 samples, the spark of the tube must pass
through 10 folds of 180º carried out in the same, at a certain distance between
them. The shortest distance between the following: 1 m, 50 cm, 30 cm, 20 cm and
10 cm in which all samples propagate to the tip is recorded as "minimum distance
between folds".
[055] 4) Test of Maximum Traction Effort by Knots
[056] The 80 cm length tube sample with a single knot
in half its length, made without tightening, attached at its ends is attached to a
traction device with a load cell capable of measuring the tensile stress with
accuracy of 100 gf and a digital display of the load cell traction effort. The tube is
manually drawn through a lever, and when the desired traction effort is reached,
the tube is started at one of its ends by a hand-operated actuator with ear fuze. The
passage of the spark by the knot or failure of the spark continuity by the knot is
observed by the relative darkening of the tube in the burned session. If the tube
fails, a less effort traction will be attempted with a new sample. If the spark passes
through the knot, greater effort traction will be attempted on a new sample. The
test result will be the highest traction in which 5 successive samples work without
fail
[057] 5) Initiation Test by Low Core Load Detonating
Cord (% of failures)
[058] 100 samples of 1m of tube are placed on the
ignition with detonating cord with load of 2 g PETN/m linear, known in the
13
industry as NP-02, attached to the cord through a J-type connector. The number of
failed parts is noted as "percentage of cord initiation failures".
[059] 6) Impact Sensitivity Test
[060] The test is performed on BAM Fall Hammer
equipment originally developed by the BAM Federal Institute for Research and
Testing of Materials from Germany in accordance with European Standard EN
13631-4: Explosives for Civil Use - High Explosives - Part 4: Determination of
Sensitivity to Impact of Explosives. The test is briefly described below:
[061] A sample of the powdered mixture shall be
subjected to the impact of a known free falling weight from a given height.
[062] The energy in which 5 successive samples
deflagrate is calculated by the formula E = m.g.h, where m = mass of free falling
weight; g = acceleration of local gravity and h = minimum height for ignition.
[063] 7) Slow Delay Element Sensitivity Test
[064] A delay element of 9 s delay time with a 30 mm
column length containing slow delay mixture without additional initiator mixture
layer is positioned at the glass PVC hose tip of 6 mm of diameter with variable
length, with the end of a spark conductor tube in accordance with the formulations
of the present invention, of 1 m in length aligned with the other end of the PVC
hose. When the tube is started, the spark must cross the free space inside the hose
and start the delay element. The longer the hose length in which the elements start
a minimum of 5 successive elements, the better the thermal performance of the
spark. The longer hose length at which the elements start without failure is noted
as "Slow Delay Element Sensitivity".
[065] 8) Tube-to-Tube Air Gap Test
[066] A piece of 3 m length spark conductor tube is cut
transversely into two 1.5 m halves, and these halves are spaced apart with a given
spacing, keeping them aligned within an aluminum guide in the shape of halfround.
The largest distance in which the spark, when crossing the open air space
14
between the tube portions, starts the second portion in 5 successive samples, is
annotated as "Tube-to-Tube Air Gap".
[067] 9) Test after Exposure to Hot Explosive Emulsion
[068] Thirty 12 m tube samples, with the ends sealed by
a rubber bushing and a fuze capsule according to the industry standard, are
immersed in conventional explosive emulsion with marine diesel oil, which causes
greater aggressiveness to the plastic, at a temperature of 65 °C for twenty-four
hours. The tubes are started and the percentage of failed parts is recorded as
"Failures by Exposure to Hot Explosive Emulsion".
[069] 10) Mixture Adhesion Test to the Tube.
[070] Ten tube samples with a length of 3 m each are
weighed in a laboratory scale with an accuracy of 0.0001 g. Thereafter, the inside
of the tubes is blown out of compressed air nozzle at a pressure of 0.2 kgf/cm2
gauge, and a flow rate of 0.2 Nm3/min. for 2 min, in order to remove the fraction
of non-adhered powder to the inner wall of the tube. The tube is weighed again,
with accuracy of 0.0001 g. Then the inside of the tubes is washed with a flow of
0.2% aqueous Sodium Hydroxide solution for dissolution of the Aluminum and of
the possible Perchlorate and drag of the nanometric Iron Oxide and Talc at a flow
rate of 200 ml/min., for a minimum of 3 min. The tube with all the powder
removed is again flushed with Acetone at a flow rate of 200 ml/min. for 1 min,
and then dried by a dry compressed air flow rate of 0.2 Nm3/min. at a pressure of
0.5 Nm3/min. for a minimum of 3 min. for drying the Acetone. The empty, dry
plastic tube is weighed with an accuracy of 0.0001 g. The mass of powder initially
present in the tube and the mass of the powder remaining adhered to the tube after
initial withdrawal with compressed air are calculated by differences, and then the
percentage by mass of loose powder in relation to the total mass of powder
initially present in the tube is calculated.
[071] Several tests were carried out to determine the
percentage ranges of the components with, for example, the following test which
15
obtained the preferred formulation of the present patent: a ball mill was mixed
with polyvinyl rubber balls for 30 minutes of electrically insulating powdered
Aluminum coated with Powdal 2900 type silica of SchlenkMetallpulver from
Germany, ferric oxide (Fe2O3) with a mean particle diameter of 30 nm of
Nanophase from England, and talc in the following proportions at weight percent:
[072] - Aluminum Powdal 2900: 45 %; and
[073] - Iron oxide NanoArc FE-300 Nanophase 30 nm:
54 %.
[074] - Talc: 1 %.
[075] It was also tested the nanometric powdered
aluminum with particle diameter of 20 to 100 nm electrically insulating coated
with aluminum oxide along with iron oxide nanometric and compatible results
were obtained.
[076] As in the fold and knot tests the distance limits
between folding for full functionality and passage of the spark by knots under
tensile stress were below that expected for many practical applications, it was
tested the use of formulations with small amounts of potassium perchlorate that
allow to improve the limits in the test of folds and knots, obtaining the minimum
value of 6% of potassium perchlorate and recommended range of 8 to 12%.
[077] The following results were obtained as described
in TABLE 1 shown at final of this report.
With the tests carried out it was concluded that the
formulation of the thermal spark conductor tube of the present invention has the
following formulation at weight percent:
[078] - Powdered aluminum with a morphology of
"flake", minimum purity 99.5%, covered and stabilized by silica or other
electrically insulating material, with a mean particle diameter between 5 and 18
μm, as Powdal 2900 from SchlenkMetallpulver or similar: 35 % to 62 % ;
16
[079] - Nanometric iron oxide with faceted almost
spherical morphology, mean particle diameter between 10 and 100 nm, such as
NanoArc FE-300 Nanophase or similar: 32 % a 60 %;
[080] - Potassium Perchlorate ranging from 0 % to 25
%.
[081] - Talc: ranging from 0.8 to 1.5 %
[082] With the tests carried out it was also concluded
that the preferred formulation of the thermal spark conductor tube of the present
invention is as follows at weight percent:
[083] - Powdered aluminum with a flake type
morphology, minimum purity 99.5%, covered and stabilized by silica or other
electrically insulating material, with a mean particle diameter of 11 μm, such as
Powdal 2900 or similar: 45 %;
[084] - Nanometric iron oxide with faceted almost
spherical morphology, mean particle diameter of 30nm, as NanoArc FE-300
Nanophase or similar: 54 %; and
[085] - Talc : 1% for common applications, where it is
not important to go through folds and knots; or alternatively:
[086] - Powdered aluminum with a flake type
morphology, minimum purity of 99.5%, covered and stabilized by silica or other
electrically insulating material with a mean particle diameter between 5 and 18
μm, such as Powdal 2900 or similar: 45 %;
[087] - Nanometric iron oxide with faceted almost
spherical morphology, mean particle diameter of 30nm, such as NanoArc FE-300
Nanophase or similar: 44 %
[088] - Potassium Perchlorate: 10 %; and
[089] - Talc: 1 % for applications where it is important
to go through folds and knots;
17
[090] With the tests carried out it was concluded that
alternatively the formulation of the thermal spark conductor tube of the present
invention may be as follows at weight percent:
[091] - Nanometric powdered aluminum with a flake
type morphology, minimum purity of 99.5%, covered and stabilized by silica or
other electrically insulating material with a mean particle diameter of 20 to 100
nm: 35 % to 62 % ;
[092] - Nanometric iron oxide with faceted almost
spherical morphology, mean particle diameter between 10 and 100 nm: 32 % to 60
%;
[093] - Potassium Perchlorate ranging from 0 % to 25
%; and
[094] - Talc: ranging from 0.8 to 1.5 %.
18
TABLE 1 - Results of Practical Tests
FORMULATION
FLASHOVER
DISTANC
E
PROPAGATIO
N SPEED
MINIMUM
PROPAGATIO
N SPACE
BETWEEN
FOLDS
MAXIMU
M
TRACTIO
N EFFORT
OF
PASSAGE
BY
KNOTS
INITIATION
BY LOW
CORE
LOADING
DETONATIN
G CORD (%
OF
FAILURES)
SENSITIVIT
Y TO
IMPACT
SLOW
DELAY
ELEMENT
SENSITIVIT
Y
TUBE
TO
TUBE
AIR
GAP
FAILURES
AFTER
EXPOSURE TO
HOT
EXPLOSIVE
EMULSION
MIXTUR
E
ADHERE
NCE TO
TUBE
AI POWDAL 2900 64.5%
Fe3O4NanometricNanoArcFE300
fromNanophase 34.5%
talc 1.0%
6 mm 964 m/s 1 m 3 f-kg 8% 9.2 N 6 cm 30 nm 25% 5 %
AI POWDAL 2900 45%
Fe3O4NanometricNanoArcFE300
fromNanophase 54%
talc 1.0%
7 mm 1091 m/s 1 m 3 f-kg zero 9.2 N 7 cm 30 nm zero 5 %
AI 62%
Fe3O4NanometricNanoArcFE300fromNanoph
ase 32% KCIO4 5 %
talc 1.0%
11 mm 1083 m/s 1 m 4 f-kg zero 9.2 N 6 cm 80 nm zero 3.8 %
AI 45%
Fe3O4NanometricNanoArcFE300fromNanoph
ase 44%
KCIO4 10 %
talc 1.0%
15 mm 1142 m/s 40 cm 9 f-kg zero 9.2 N 12 cm 100 nm zero 6 %
AI 35%
Fe3O4NanometricNanoArcFE300fromNanoph
ase 39%
KCIO4 25 %
talc 1.0%
22 mm 1260 m/s 30 cm 2 f-kg zero 9.2 N 5 cm 15 nm 15 % 3.2 %
Standard HMX/Al mixture of conventional
shock tube with single layer of plastic
6 mm 2000 m/s 1 m 2 f-kg zero 3.8 N
FAILS TO
IGNITE,
EVEN AT
ZERO
DISTANCE
10 mm
NOT
PERFORMED
NOT
PERFOR
MED
Standard HMX/Al mixture of conventional
shock tube with double layer of plastic
6 mm 2000 m/s 50 cm 8 f-kg zero 3.8 N
FAILS TO
IGNITE,
EVEN AT
ZERO
DISTANCE
10 mm
NOT
PERFORMED
NOT
PERFOR
MED
19
WE CLAIM:
1. "THERMAL SPARK CONDUCTOR TUBE
USINGNANOMETRIC PARTICLES", in the form of a flexible plastic tube,
with internal diameter between 1.0 and 1.5 mm, and outer diameter between 2.8
and 3.4 mm, substantially hollow, containing a thin powder pyrotechnic mixture
deposited on its inner wall, characterized in that the pyrotechnic mixture has the
following formulation at weight percentage:
- Aluminum powder with “flake”type morphology,
minimum purity 99.5%, covered and stabilized by silica or other electrically
insulating material, with a mean particle diameter between 5 and 18 μm: 35% to
62%;
- Nanometric iron oxide with faceted almost
spherical morphology, average particle diameter between 10 and 100 nm: 32% to
60%;
- Potassium Perchlorate ranging from 0% to 25%;
and
- Talc: Ranging from 0.8 to 1.5%
2. "THERMAL SPARK CONDUCTOR TUBE
WITH USE OF NANOMETRIC PARTICLES", for common applications
where the passage through kinks and knots is not important, in the shape of a
flexible plastic tube, with internal diameter between 1.0 and 1.5 mm, and outer
diameter between 2.8 to 3.4 mm, substantially hollow, containing a fine powder
pyrotechnic mixture deposited on its inner wall, according to claim 1,
characterized in that the pyrotechnic mixture has the following preferential
formulation at weight percentage:
- Aluminum powderwith “flake”type morphology,
minimum purity 99.5%, covered and stabilized by silica or other electrically
insulating material, with a mean particle diameter of 11 μm: 45%;
20
- Nanometric iron oxide with faceted almost
spherical morphology, with a particle diameter of 30 nm: 54%; and
- Talc : 1 %
3. "THERMAL SPARK CONDUCTOR TUBE WITH USE OF
NANOMETRIC PARTICLES", for applications where the passage through
folds and knots is important, in the shape of a flexible plastic tube, with internal
diameter between 1.0 and 1.5 mm, and outer diameter between 2.8 and 3.4 mm,
substantially hollow, containing deposited on its inner wall a fine powder
pyrotechnic mixture according to claim 1, characterized in that the pyrotechnic
mixture has the following preferential formulation at weight percentage:
- Aluminum powder with “flake”typemorphology,
minimum purity 99.5%, covered and stabilized by silica or other electrically
insulating material, with a mean particle diameter of 11 μm: 45%;
- Nanometric iron oxide with faceted almost
spherical morphology with a particle diameter of 30 nm: 44 %
- Potassium Perchlorate:10 %; and
- Talc: 1 %
4. "THERMAL SPARK CONDUCTOR TUBE
WITH USE OF NANOMETRIC PARTICLES", in the shape of a flexible
plastic tube, having an internal diameter between 1.0 and 1.5 mm, and an outer
diameter between 2.8 and 3.4 mm, substantially hollow, containing a thin powder
pyrotechnic mixture deposited on its inner wall, characterized in that alternatively
the pyrotechnic mixture has the following formulation at weight percentage:
- Nanometric aluminum powder with a “flake”
type morphology, minimum purity 99.5%, covered and stabilized by silica or other
electrically insulating material, with a mean particle diameter of 20 to 100 nm:
35% to 62%;
21
- Nanometric iron oxide with faceted almost
spherical morphology, mean particle diameter between 10 and 100 nm: 32% to60
%;
- Potassium Perchlorate ranging from 0 % to 25 %;
and
- Talc: Ranging from 0.8 to 1.5 %