Note: Descriptions are shown in the official language in which they were submitted.
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IGNITION FORMULATION FOR AN INCENDIARY MATERIAL AND A SYSTEM FOR
CONTROLLING GENERATION OF A FLAME FROM AN INCENDIARY CAPSULE
Technical Field
The present disclosure relates to an ignition formulation for an incendiary
material and
a system for controlling generation of a flame from an incendiary capsule. An
exemplary use for the ignition formulation and said system is for fire control
and
forestry management procedures such as controlled burns and back burning.
Background Art
The present Applicant has developed numerous incendiary capsules and machines
for
airborne dispensing of incendiary capsules. Examples of these are described in
Australian patent no. 2003204999; and application numbers 2010256280;
2011223497; and 2011293093. The incendiary material used in each instance
comprises at least potassium permanganate. The potassium permanganate is held
within a capsule. The capsules are subsequently injected with an initiator in
the form of
a glycol using an automated dispensing machine and subsequently dropped to the
ground. The dispensing machine can be mounted in or on an aircraft so that the
capsules once injected with the initiator are dropped from the aircraft to
fall to the
ground.
The potassium permanganate and initiator react exothermically to produce a
flame.
Efficacy is maximised if the flame is generated when the capsule is on the
ground
rather than in the air. In order to exert some control over the period of time
between
initial injection of the initiator and the production of a flame third parties
have been
known to mix glycol with water. This slows the exothermic reaction providing
sufficient
time for the capsule to reach the ground prior to the generation of the flame.
Injection
of a mixture of water and glycol into a capsule of potassium permanganate has
however been known to cause the capsule to explode due to the generation of
steam
prior to the generation of a flame. Moreover, the presence of water may quench
the
flame or at least reduce flame size.
The above references to background art do not constitute an admission that the
art
forms a part of the common general knowledge of a person of ordinary skill in
the art.
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The above references are also not intended to limit the application of the
formulation,
system and methods as disclosed herein.
Summary of the Disclosure
The general concept of the present disclosure is to provide an ignition
formulation and
a system for controlling the generation of a flame from an incendiary capsule
in which
ignition time of the incendiary material can be controlled or at least delayed
in
comparison to a mixture of corresponding amounts of potassium permanganate and
glycol. The present disclosure is based on a discovery that the ignition time
can be
controlled and/or delayed by the addition of an inhibitor capable of slowing
the rate of
exothermic reaction between potassium permanganate and glycol (or other
initiators),
thereby providing a delay period between contact of the glycol-inhibitor
mixture with
potassium permanganate and generation of the flame.
In one aspect, there is disclosed an ignition formulation for an incendiary
material. The
ignition formulation comprises an initiator capable of reacting exothermically
with the
incendiary material to an extent sufficient to generate a flame when contacted
with the
incendiary material. The ignition formulation also comprises a non-aqueous
inhibitor
capable of slowing the rate of exothermic reaction between the incendiary
material and
the initiator, thereby providing a delay period between contact of the
ignition
formulation with the incendiary material and generation of the flame.
The incendiary material may be potassium permanganate. The initiator may be a
glycol, a polyol, a glycol ether, or a mixture thereof.
In one embodiment the inhibitor is non-reactive with the incendiary material.
Advantageously, the inhibitor behaves as a heat sink prior to generation of
the flame,
thereby extending the delay period between contact of the ignition formulation
with the
incendiary material and generation of the flame. The inhibitor may be a
compound
selected from a group comprising long chain (C5-C12) alcohols, alkanes,
alkenes,
cycloalkanes, ethers, esters, ketones, carboxylic acids, aromatic
hydrocarbons,
organonitrates, diesel, biodiesel, kerosene, modified kerosene and oils.
In preferred embodiments, the inhibitor may be combustible. Although the
presence of
the inhibitor may delay onset of a flame when the initiator is mixed with the
incendiary
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material, once the flame is generated the combustible material combusts and
enhances the generated flame.
In one embodiment the initiator and the inhibitor may be miscible liquids.
In alternative embodiments the initiator and the inhibitor may be immiscible
liquids. A
mixture of immiscible liquids may separate over time into a bi-liquid phase
which is
undesirable for several reasons. In these particular embodiments the
formulation may
be adapted to provide a stable homogenous mixture of the immiscible initiator
and the
inhibitor.
For example, the ignition formulation may further comprise a co-solvent in
which the
initiator and the inhibitor are soluble. Alternatively, the ignition
formulation may further
comprise an agent capable of forming a stable homogenous mixture of the
immiscible
initiator and the inhibitor, preferably in the form of an emulsion or
microemulsion.
Examples of suitable agents include, but are not limited to, emulsifiers or
surfactants.
In one embodiment the initiator and the inhibitor are provided in a ratio to
delay
generation of a flame by a period in a range of 20 seconds to 120 seconds from
a time
of initial contact with the incendiary material.
In another aspect, a system for controlling the generation of a flame from an
incendiary
capsule is disclosed. The system comprises a quantity of incendiary material
sealed in
a capsule body and an ignition formulation as described herein. The system may
further comprise a means for injecting the ignition formulation into the
capsule body.
A method of making an ignition formulation for an incendiary material is also
disclosed.
The method comprises providing an initiator capable of reacting exothermically
with the
incendiary material to an extent sufficient to generate a flame when contacted
therewith, and mixing the initiator with an inhibitor capable of slowing the
rate of
exothermic reaction between the incendiary material and the initiator, thereby
providing
a delay period between contact of the ignition formulation with the incendiary
material
and generation of the flame.
A method of controlling the generation of a flame from an incendiary capsule
comprising a quantity of incendiary material sealed in a capsule body is also
disclosed.
The method comprises injecting the ignition formulation as described herein
into the
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capsule body, thereby causing a delay period between contact of the ignition
formulation with the incendiary material and generation of the flame.
Detailed Description of Specific Embodiments
Embodiments of an ignition formulation for an incendiary material, a system
for
controlling the generation of a flame from an incendiary capsule and methods
of
making the ignition formulation and igniting the incendiary capsule will now
be
described by way of example only, and with particular (though not exclusive)
reference
to providing fire control and forestry management procedures such as
controlled burns
and back burning.
Ignition formulation
The ignition formulation for an incendiary material comprises an initiator
capable of
reacting exothermically with the incendiary material to an extent sufficient
to generate a
flame when contacted therewith. Generally, the incendiary material is
potassium
permanganate, preferably in the form of granules or powder.
The initiator may be any substance capable of reacting exothermically with the
incendiary material to an extent sufficient to generate a flame when contacted
therewith. In one embodiment, the initiator may be glycol, polyol, a glycol
ether or a
mixture thereof.
In use, the initiator is contacted with the incendiary material by injecting
the initiator into
a capsule body of an incendiary capsule containing the incendiary material.
For
convenience of use in this manner, the initiator is a liquid, preferably
having a viscosity
suitable for injection thereof into the capsule body. It will be appreciated
by persons
skilled in the art that two or more glycols, polyols or glycol ethers may be
mixed to
obtain an initiator liquid having suitable viscosity for injection thereof
into the capsule
body. For example, polyols such as glycerol are very good initiators but tend
to be
very viscous, whereas a mixture of glycerol with glycol ethers has lower
viscosity and
is still capable of reacting exothermically with the incendiary material to an
extent
sufficient to generate a flame when contacted therewith.
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Examples of suitable glycols include, but are not limited to, glycerol,
ethylene glycol,
propylene glycol, diethylene glycol, triethylene glycol and low molecular
weight
polyethylene glycols.
A polyol is an organic compound with two or more hydroxyl functional groups.
Examples of suitable polyols include, but are not limited to, diols, triols,
tetrols and so
forth.
Examples of suitable glycol ethers include, but are not limited to, diethylene
glycol
monomethyl ether, triethylene glycol monomethyl ether, ethylene glycol
monoethyl
ether, diethylene glycol monoethyl ether, monoethylene glycol monobutyl ether,
diethylene glycol monobutyl ether, triethylene glycol monobutyl ether,
propylene glycol
monomethyl ether, and dipropylene glycol monomethyl ether.
The ignition formulation also comprises a non-aqueous inhibitor capable of
slowing the
rate of exothermic reaction between the incendiary material and the initiator,
thereby
providing a delay period between contact of the ignition formulation with the
incendiary
material and generation of the flame.
Advantageously, it is believed that the inhibitor acts in part as a heat sink
to slow down
the exothermic reaction between the incendiary material and the initiator
without being
vaporised to an extent sufficient to rupture the capsule, or at least not
until a flame has
been generated. In a preferred embodiment, the inhibitor may be combustible.
Advantageously, if a combustible inhibitor is employed in the ignition
formulation, the
inhibitor has the effect of adding heat to the flame once generated.
Preferably, the inhibitor is non-reactive with the initiator and the
incendiary material.
The inhibitor may have a melting point less than 30 C, preferably less than 0
C. The
inhibitor may have a boiling point of > 100 C. The inhibitor may have a flash
point
>63 C. The inhibitor has a high calorific value. The inhibitor preferably has
low odour
and low toxicity. The inhibitor may have a low vapour pressure. The inhibitor
may
have a low viscosity in the temperature range 0 to 40 C. However, in use in
cold
environments, the inhibitor may have a low viscosity in the temperature range
down to
-30 C.
The inhibitor may be a compound selected from a group comprising long chain
(C5-C12)
alcohols, alkanes, alkenes, cycloalkanes, ethers, esters, ketones, carboxylic
acids,
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aromatic hydrocarbons, organonitrates, diesel, biodiesel, kerosene, modified
kerosene
and oils.
Exemplary long chain (C5-C12) alcohols include, but are not limited to, linear
or
branched pentanol, hexanol, heptanol, octanol, nonanol, decanol, undecanol and
dodecanol. Exemplary alkanes include, but are not limited to, linear or
branched
C4-C15 alkanes. Exemplary alkenes include, but are not limited to, linear or
branched
C4-C15 alkenes. Exemplary cycloalkanes include, but are not limited to, C5-C20
cycloalkanes. Exemplary ethers include, but are not limited to, ethers having
mw
> 100. Exemplary esters include, but are not limited to, esters having mw >
100.
Exemplary ketones include, but are not limited to, ketones having mw > 100.
Exemplary organonitrates include, but are not limited to, ethylhexyl nitrate
(EHN). EHN
and similar compounds in this class may be suitable because the compound is
self-
reactive and undergoes a self-accelerating decomposition when heated to above
100 C. Exemplary oils include, but are not limited to, mineral oils or
vegetable oils,
essential oils (e.g. pine oils), white oil, heating oil, white spirits and
mineral turpentine.
In use, the inhibitor is mixed with the initiator, and the resulting mixture
may be later
injected into the capsule body containing the incendiary body just prior to
deployment
of the incendiary capsule.
In one embodiment the initiator and the inhibitor are miscible liquids.
In alternative embodiments the initiator and the inhibitor may be immiscible
liquids. A
mixture of immiscible liquids may separate over time into a bi-liquid phase
which is
undesirable for several reasons. In these particular embodiments the
formulation may
be adapted to provide a stable homogenous mixture of the immiscible initiator
and the
inhibitor.
For example, the ignition formulation may further comprise a co-solvent in
which the
initiator and the inhibitor are soluble. Examples of suitable co-solvents
include, but are
not limited to, long chain (C5-C12) alcohols, esters such as amyl acetate and
n-pentyl
propionate, ethers such as dilauryl ether, glycol ether acetates such as 2-(2-
butoxyethoxy)-ethyl acetate, glycol ethers, solvents such as N-methyl-
pyrrolidone,
gamma butyrolactone, 1,4-dioxane. It will be appreciated that in some
embodiments
mixtures of one or more co-solvents may be employed in the ignition
formulation.
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Alternatively, the ignition formulation may further comprise an agent capable
of forming
a stable homogenous mixture of the immiscible initiator and the inhibitor,
preferably in
the form of an emulsion. Suitable agents include, but are not limited to,
emulsifiers or
surfactants. Exemplary emulsifiers include, but are not limited to, alcohol
ethoxylates,
alkylphenol ethoxylates, fatty acid ethoxylates, sorbitan esters including
laurates,
myristates and oleates, sorbitan ester ethoxylates or polysorbates, or
mixtures thereof.
In preferred embodiments, two or more emulsifiers may be employed.
Particularly
preferred are those emulsifiers having low hydrophile lipophile balance (hlb)
number or
emulsifiers with a relatively low degree of ethoxylation.
It will be appreciated that the ignition time may be influenced by the purity
of the
potassium permanganate employed as the incendiary material, the particle size
of the
crystals or granules and the ambient temperature.
The initiator and the inhibitor may be provided in a ratio to delay generation
of a flame
by a period in a range of 20 seconds to 120 seconds from a time of initial
contact with
the incendiary material. The ratio of initiator to inhibitor may be in the
range of 1:10 to
10:1.
System for controlling the generation of a flame from an incendiary capsule
The system for controlling the generation of a flame from an incendiary
capsule
comprises a quantity of incendiary material sealed in a capsule body; and an
ignition
formulation as described herein.
The capsule body comprises a receptacle portion and a planar lid, wherein the
lid is
adhered to the receptacle to define a space in which the incendiary material
is held
and into which the ignition formulation can be injected.
The capsule body may be conveniently fabricated from a plastics material.
Throughout
this specification and claims the term "plastics material" is intended to be
interpreted
broadly to encompass synthetic or fossil fuel derived plastics material and
bioplastics
material, unless from the specific context of the use of the term an alternate
meaning is
clearly intended. The term "bioplastic" is intended to be interpreted broadly
to
encompass forms of plastics which are able to biodegrade in time and thereby
minimise adverse environmental effects. Non limiting examples of synthetic or
fossil
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fuel derived plastics material are: polyethylene terephthalate; high-density
polyethylene; polyvinyl chloride; low-density polyethylene; and polypropylene.
Non
limiting examples of bioplastics are; starch based plastics, cellulose based
plastics,
bioplastic derived from microbiota; and polylactic acid (PLA) plastics.
Preferably, the capsule body is fabricated from an ABS plastics material.
The system also comprises an injector for injecting the ignition formulation
into the
capsule body.
The system may further comprise a dispenser for dispensing the capsule body
injected
with the ignition formulation. The dispenser may be configured for dispensing
said
injected capsule bodies from an air-borne vehicle, a land vehicle, or by a
ground-based
operator. Exemplary dispensers have been described in Australian patent no.
2003204999; and application numbers 2010256280; 2011223497; and 2011293093.
Method of making an ignition formulation for an incendiary material
The method of making an ignition formulation for an incendiary material
comprises
mixing an initiator, wherein the initiator is capable of reacting
exothermically with the
incendiary material to an extent sufficient to generate a flame when contacted
therewith, with an inhibitor capable of slowing the rate of exothermic
reaction between
the incendiary material and the initiator, thereby providing a delay period
between
contact of the ignition formulation with the incendiary material and
generation of the
flame.
The initiator and inhibitor are as described previously. The initiator and the
inhibitor
may be mixed in a ratio of initiator to inhibitor in the range of 1:10 to
10:1.
Method of controlling the generation of a flame from an incendiary capsule
Said method comprises injecting the ignition formulation as described above
into the
capsule body, thereby causing a delay period between contact of the ignition
formulation with the incendiary material and generation of the flame.
The injected capsules are then immediately dispensed from air-borne vehicle
(i.e. light
aircraft or helicopter) to the desired area. Typically, the injected capsules
are
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dispensed from an altitude of 100 to 6000 feet. The delay period between
contact of
the ignition formulation with the incendiary material and generation of the
flame allows
the injected capsule to clear the vicinity of the air-borne vehicle before
ignition.
Moreover, the delay period means that the incendiary capsule is likely to
generate a
flame on or proximal to the ground rather than mid-air.
In an alternative embodiment, the injected capsules may be immediately
dispensed to
the desired area from a land vehicle or from a hand-held propulsion device by
ground-
based operators. The delay period between contact of the ignition formulation
with the
incendiary material and generation of the flame allows the land vehicle or the
ground-
based operators to clear the vicinity of the injected capsule before ignition.
In another alternative embodiment, the injected capsules may be immediately
dispensed to the desired area from a water-borne vehicle. The dealy period
between
contact of the ignition formulation with the incendiary material and
generation of the
flame allows water-borne vehicle to clear the vicinity of the injected capsule
before
ignition.
Examples
Non-limiting Examples of an ignition formulation for controlling the
generation of a
flame from an incendiary capsule will now be described.
Stoichiometrically, the ratio of glycerol to potassium permanganate is
approximately
1:6 by weight according to the reaction:
14KMna4 + 4CH(OH)(CH2OH)2 - 7K2CO3 + 7Mn203 + 5CO2 + 16H20
For ethylene glycol the ratio is practically the same:
14KMn04 + 6(CH2OH)2 - 7K2CO3 + 7Mn203 + 5CO2 + 16H20
In one embodiment, the incendiary material (i.e. potassium permanganate) may
be
ignited by injecting the ethylene glycol at any ratio from about 1 part
ethylene glycol to
10 parts permanganate to 1 part ethylene glycol to 3 parts permanganate.
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In the examples of ignition formulation described below, 0.15 to 0.3 mL
ignition
formulation is injected into a capsule body containing 1.42 g potassium
permanganate.
This is equivalent to a ratio of approximately 1 part liquid to 10 parts KMn04
by weight
to 1 part liquid to 5 parts KMn04 by weight. The examples below are designed
to
provide a delay from injection to generation of the flame of about 25 seconds
at
ambient temperature 30 C to 35 C.
Example 1
______________ Ignition formulation %w/w
Diethylene glycol monobutyl ether 55
Dodecanol 45
Example 2
Ignition formulation %w/w
Diethylene glycol monobutyl ether 60
Dearomatised kerosene 30
Octanol 10
Example 3
Ignition formulation __________________ %w/w
Diethylene glycol monoethyl ether 40
2-(2-butoxyethoxy)-ethyl acetate 30
Diesel fuel 30
Example 4
Ignition formulation %w/w
Diethylene glycol monoethyl ether 40
Dearomatised kerosene 30
Nonylphenol ethoxylate 20
Example 5
Ignition formulation %w/w
Diethylene glycol monoethyl ether 50
Dearomatised kerosene 30
Octanol 10
Ethylhexyl nitrate 10
Example 6
Ignition formulation %w/w
Ethylene glycol ________________________ 25
Diethylene glycol 25
Amyl acetate 10
Dodecanol 40
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Example 7
Ignition formulation Yow/w
Diethylene glycol monoethyl ether 60
Mineral oil 25
Alcohol ethoxylate blend 15
Numerous variations and modifications will suggest themselves to persons
skilled in
the relevant art, in addition to those already described, without departing
from the
disclosure. All such variations and modifications are to be considered within
the scope
of the disclosure.
In the claims which follow, and in the preceding description, except where the
context
requires otherwise due to express language or necessary implication, the word
"comprise" and variations such as "comprises" or "comprising" are used in an
inclusive
sense, i.e. to specify the presence of the stated features but not to preclude
the
presence or addition of further features in various embodiments of
formulation, system
and methods as disclosed herein.
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