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Description  |
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BACKGROUND OF THE INVENTION
This invention relates to substantially nonaqueous persistent
thixotropically gelled fire suppressant compositions wherein a carrier
material is permeated with a fire suppressant agent and is suspended in a
thixotropically gelled fire extinguishing dispersant in which the carrier
material is insoluble. When the suppressant composition is dispersed from
any suitable container onto an object in the vicinity of the combustion,
the fire is extinguished and reignition is prevented by the release of the
suppressant agent permeating the carrier material over a period of time.
Several available fire extinguishing compositions are presently capable of
extinguishing a fire, however, the problem of reignition still remains a
high probability if hot spots and a fuel source remain present. These
conditions are present in aircraft engine nacelles, on and off-road
vehicles, engine and power train compartments, live electrical wire
installations, motors, upholstery, etc.
The compositions of the present invention contain both extinguishing
materials to quickly extinguish a fire and means for suppressing further
combustion of combustible objects which are potential fuel sources.
Many prior art compositions, particularly in the form of aqueous forms, are
claimed to have persistent qualities. Foam extinguishment involves the
expansion of water with air or other gases to form a sticky, but flowable,
stabilized foam. A layer of foam deposited on a burning object coats and
separates the fuel from the flame front, minimizes contact with oxygen and
provides some cooling action. Thus, the fire is smothered. Foams are
generally inexpensive and relatively easy to apply on a large scale. One
of their major advantages is that they will persist for many hours and
prevent reignition. However, the quantities of water needed for the foam
fire extinguishing agents are too great for portable units and they cannot
be used on electrical fires. Also, post-fire clean-up can be a problem.
Another type of extinguishing material includes vaporizing liquid
extinguishers. The flame interference of these extinguishers is believed
to be due to thermal decomposition of the vaporizing liquid to give low
concentrations of flame inhibitors which quench the chemical reactions of
the flame. Chlorinated fragments, as from carbon tetrachloride and
brominated fragments (as from bromochloromethane) are effective. The rate
of thermal decomposition, which should be rapid, volatility, which should
be intermediate, and mode of application are significant.
Dry powder extinguishing agents have also found widespread use. While it
was initially thought that dry powder extinguishants functioned by
decomposition to give CO.sub.2 (which would smother the fire), it has been
established that this is not the case. There is little measurable
decomposition, and powders which cannot give CO.sub.2 (such as NH.sub.4
H.sub.2 PO.sub.4) are effective. KHCO.sub.3 is twice as effective as
NaHCO.sub.3. These materials appear to react by virtue of their chemical
surface with the flame propagating intermediates in a flame front. Dry
powder clouds are believed also to exert a thermal shielding between the
hot flame front and the cooler fuel. The 10-40 micron coated particles
generally used appear to be a compromise between the need for a large
number of particles (favoring smaller particle size), the need to
penetrate the hot gases around the flame and be propelled to the flame
front (favoring larger particles), and the need for flowability and
storability without packing (hence, the coatings). The dry powders as
conventionally used are necessarily very bulky and require relatively
large extinguisher tanks.
The following patents disclose various types of fire extinguishing
compositions and are believed to represent the closest prior art.
The closest disclosure is believed to be British Patent No. 1,349,508 of
Cottrell et al. This patent discloses a fire extinguishing composition in
the form of an aqueous gel which produces an incombustible adherent
protective layer on burning materials to minimize reignition. The
composition comprises an aqueous gel made by at least partially
neutralizing an aqueous solution of an alkali metal silicate with an
organic or inorganic acid or acidic salt. The acids preferred are those
which, besides having a gelling agent themselves, possess some
fire-fighting properties, for example phosphoric acids, boric acids and
salts thereof. Although the precise chemical structure of the gels is not
known, the gels are stable to mechanical agitation. In other words, the
gels are not thixotropic.
The ingredients of the patented composition initially may be in the form of
powders to be mixed with and dissolved in water to form the aqueous gels.
Flow additives such as precipitated silica may be added to the powders to
prevent caking on storage or transport or to aid the flow of the powder
into a dissolution vessel or water stream. Other compounds may be added to
the aqueous mixture before or after gelling. The additives may modify the
viscosity of the gel to make it more suitable for spraying or to modify
the surface properties of the gel to aid its flow or conversely to
increase the adhesion of the gel to the surfaces of combustible material.
The Cottrell et al. patent also discloses incorporating an organic
compound, which may be for example a fire-retardant compound, into the
gelling composition and allowing the volatilization of the organic
compound to blow the composition to a foam. Suitable compounds include
fluorocarbons optionally containing chlorine and/or bromine and preferably
containing not more than 3 carbon atoms. Especially suitable compounds are
disclosed as being bromochlorodifluoromethane, bromopentafluoroethane,
dibromodifluoromethane, 1,2-dibromotetrafluoroethane, and
bromotrifluoromethane. The addition of 1 to 5 percent of high surface area
silica to the composition containing volatile fluorocarbons is disclosed
as being advantageous because the undesirable phase separation of
components on storage is minimized.
The Cottrell et al. patent neither discloses nor suggests the present
invention. The present invention relates to a thixotropically gelled fire
extinguishing composition wherein a fire suppressant agent permeates a
carrier material. The carrier material permeated with suppressant agent is
insoluble in a fire extinguishing dispersant agent into which it is
suspended. The entire composition of the present invention is then
thixotropically gelled to provide a stable suspension which is easily
transported and dispensed. The permeated carrier material adheres to
objects in the vicinity of combustion to suppress combustion by slowly
releasing the suppressant agent permeating the carrier material.
Moroever, the gelled dispersant agent does not itself adhere to the object.
Rather, the dispersant agent almost immediately volatizes to disperse the
permeated carrier material and to smother, cool and combine with the free
radicals of the combustion process to break the combustion chain, thereby
extinguishing a fire to which the composition is applied. Cottrell et al.
does not disclose a composition containing insoluble carrier material
permeated with fire suppressant agent which is suspended in a
thixotropically gelled fire extinguishing dispersant agent.
U.S. Pat. No. 3,402,665 of Tarpley, Jr. et. al. discloses a non-pyrotechnic
disseminator wherein the material to be disseminated may comprise finely
divided powders suspended within a thixotropically gelled liquid which
comprises at least a portion of liquefied gas. The only mention in this
patent that the material has use as a fire extinguisher is a statement
that all of the gelled liquid may consist of a liquefied gas, giving a
composition having primary utility where the liquefied gas has the
property of augmenting the functionality of the finely divided powder, as
in the case of liquefied Freon being used in a fire extinguisher. There is
no disclosure or suggestion in the patent that a fire suppressant agent
permeates a carrier material resulting in a persistent fire suppressant
composition.
British Patent No. 1,236,075 of Hollows discloses a nonaqueous fire
extinguishing liquid, for example, bromochlorodifluoromethane, and a
specific finely divided fire extinguishing powder. The powdered fire
extinguishing material can be in the form of a dispersion or suspension in
the fire extinguishing liquid, these states being assisted if desired by
suitable dispersing agents. One or more of the known perhalocarbon liquid
propellents can be mixed with the composition or its components. The
specific fire extinguishing powder is that disclosed and claimed in
British Patent No. 1,168,092 of Birchall which comprises the reaction
product between urea and bicarbonates, carbonates, sesquicarbonates and
hydroxides of sodium and potassium, having an empirical molecular formula
of MC.sub.2 N.sub.2 H.sub.3 O.sub.3, where M represents an atom of
potassium or sodium.
German Auslegeschrift No. 1,211,493, dated Feb. 24, 1966, discloses a fire
extinguishing composition especially for hand fire extinguishers
consisting of a mixture of solid fire extinguishing powders, especially
those based on carbonates, phosphates and sulfates, and liquid fluorinated
(halo) paraffins, especially bromodifluoromethane and/or
bromotrifluoromethane, which simultaneously act a propellants.
Australian Patent No. 227,557 of Warnock et al. discloses a dry chemical
fire extinguishing composition comprising a dry chemical fire
extinguishing powder, a powdered adsorbing agent and a gaseous expellant,
a portion of the gaseous expellant being adsorbed by the adsorbing agent
in an amount to maintain internal gaseous pressure in the container at a
predetermined pressure at room temperature, the total amount of the
gaseous expellant in the container being capable of expelling
substantially most of the dry chemical in the container. The adsorbing
agent can be silica gel, activated charcoal, attapulgus clay, synthetic
zeolites, activated alumina, cracking catalysts of the type used in
petroleum refining containing silica and various proportions of alumina,
as well as the high surface area porous materials disclosed in U.S. Pat.
Nos. 2,866,760. The expellant gas comprises a halogenated hydrocarbon and
a gas selected from the group consisting of carbon dioxide, nitrogen,
ethane, nitrous oxide and air.
U.S. Pat. No. 3,258,423 of Tuve et al. discloses a fire extinguishing
composition known as "light water". It comprises potassium bicarbonate
which may be silicone coated, water and particular types of perfluoro
surfactants which form a stable foam when aerated with a gas, such as air
or difluorodichloromethane. It is disclosed that the foam blocks the
feedback of radiant energy to a fuel surface and prevents further release
of flammable vapor after the flames have been suppressed, to prevent
reignition of burning liquids, particularly.
U.S. Pat. No. 3,267,030 of Dessart discloses a dry powder type of fire
extinguishing composition comprising 80-98% of a finely divided alkali
metal bicarbonate, 1-19% of talc and 1-8% of very fine grain silica. The
alkali metal bicarbonates may be coated with silicone oil. The composition
is disclosed as possessing excellent compatability with foams and
excellent mobility.
U.S. Pat. No. 3,609,074 of Rainaldi et al. discloses a flame extinguishing
foam forming composition containing 5-25 weight percent of a bromine
containing halogen saturated alkane of low carbon number (C.sub.1 to
C.sub.6). The composition also contains substances conventional in foaming
liquid flame extinguishing compositions, such as water, emulsifiers or
foam stabilizing surfactants, propellents, antifreezing liquids, corrosion
inhibitors, buffer substances, and thickening and carrying agents. Sodium
silicates or potassium silicates are disclosed as the thickening and
carrying agents.
U.S. Pat. No. 3,655,554 of Fink et al. discloses fire extinguishing
compositions, such as foam forming liquids containing surface active
substances, which are enhanced by incorporating into the agent about 1-10
weight percent of finely dispersed silica. It is preferred that the silica
be present in the fire extinguishing liquids in colloidally dissolved
form. The foaming agent and/or foam stabilizer may be mixed with the
finely dispersed silica in dry form to obtain a powder which is then added
to water to form the foam.
U.S. Pat. No. 4,042,521 of Dunn discloses a dry fire extinguishing
composition comprising between about 50-95% of an alkali metal bicarbonate
or alkaline earth metal carbonate and between about 50-5% of a metal
silicate. Very small amounts of desiccants, such as magnesium stearate,
talc, silica, silica gel, diatomaceous earth, calcium chloride, etc., may
be added to the dry fire extinguishing composition to prevent the tendency
of the composition to cake or agglomerate when subjected to moisture over
long periods of time. The composition is disclosed as being effective in
preventing flashback or reignition, particularly of Class B fires.
The composition of the present invention is neither disclosed nor suggested
by any of the above-identified references and represents an improvement in
persistent fire extinguishing and suppressing compositions.
SUMMARY OF THE INVENTION
The present invention comprises a substantially nonaqueous persistent
thixotropic fire suppressant composition comprising a fire suppressant
agent, a carrier material, the suppressant agent permeating the carrier
material to form a suppressant permeated carrier material, a fire
extinguishing dispersant, the carrier material being insoluble in the
dispersant, the permeated carrier material being suspended in the
dispersant, and a gelling agent in an amount effective to thixotropically
gel the suspension of permeated carrier material and dispersant, the
permeated carrier material being capable of adhering to an object in the
vicinity of combustion.
The invention also includes a method of persistently suppressing combustion
by dispersing the hereinafter described composition in the vicinity of a
fire, whereby the permeated carrier material adheres to an object or
objects in the vicinity of the fire and releases the permeating
suppressant agent over a period of time. The relatively slow release of
suppressant which permeates the carrier material is effective in
preventing reignition of an extinguished fire and is also effective in
preventing the spread of the fire to combustible fuel sources in the
vicinity of the fire. The compositions according to the present invention
are effective in persistently suppressing all classes of fires.
Definitions
The definitions given for the following terms shall apply throughout this
application:
"Adhere" means to hold in contact with by means of chemical adhesion,
thermoplastic adhesion, magnetic adhesion, electrostatic adhesion and/or
mechanical adhesion.
"Dispersant" is a substance in which a solid material can be suspended
under pressure, and which, upon the release of the pressure, as in being
dispensed into the atmosphere from a pressurized container, propels,
expels, spreads or disseminates the suspended solid material in all
directions. "Percent" as applied to a component or ingredient of the
composition means weight percent of the component or ingredient based on
the total weight of the composition.
"Permeate" means to diffuse the permeating substance throughout the entire
structure of the permeated material by means of absorption, adsorption,
coating, impregnation, penetration, saturation and/or chemical combination
in such a manner that the permeating substance is capable of being
released from the permeated material.
"Persistent" with respect to the combustion suppressant qualities of the
composition means that the ability of the composition to suppress
combustion continues for a longer period of time than with compositions
containing similar ingredients but which do not have a carrier material
permeated with a suppressant agent.
"Substantially nonaqueous" with respect to the described and claimed
composition means that the composition contains substantially no free
water, although some hydrated solid suppressant agents and/or carrier
materials may be present in the composition.
"Suppress" means to extinguish or to inhibit or to retard the growth or
development of combustion. Thus, a suppressant agent extinguishes a fire,
prevents reignition of the extinguished fire and may be used to prevent
combustion of new fuel sources in the area of existing, potential or
previously extinguished combustion.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention is comprised of four principal components: a
suppressant agent, a carrier material, a fire extinguishing dispersant and
a gelling agent. Although some of these components may be present in prior
art extinguishing compositions, they are combined according to the present
invention in a synergistic manner to produce a stable, persistent and
effective fire suppressing composition. It is believed that the
composition according to the present invention possesses synergistic
characteristics and produces a synergistic result when compared to the
components of the composition when used separately or as combined in the
prior art. Thus, in the present invention, the suppressant agent permeates
the carrier material so that it is slowly released at or near the site of
combustion.
Any suppressant agent capable of permeating a carrier material to provide a
persistent action may be used in the compositions according to the present
invention. In most cases, liquids having boiling points above about
40.degree. F. are preferred because of their ability to easily permeate a
carrier material. However, solids, solutions, suspensions, dispersions,
and emulsions may also be effective suppressant agents. Typical solid
suppressant agents include sodium salts, potassium salts, phosphates,
carbonates, bicarbonates and the like. The suppressant may be released by
a chemical reaction, such as the decomposition of a permeated carrier
material which melts and decomposes upon contact with a hot surface.
The suppressant agent may include various halogenated hydrocarbon fire
suppressant agents well known to those skilled in the art, such as
1,2-dibromotetrafluoroethane, having a vapor pressure of 14.7 psi absolute
at 117.5.degree. F., 1,2-difluorotetrachloroethane, having a vapor
pressure of 14.7 psi absolute at 200.degree. F., bromochloromethane,
having a vapor pressure of 14.7 psi absolute at 152.6.degree. F.,
dibromodifluoroethane, having a vapor pressure of 14.7 psi absolute at
76.degree. F., and the like. The suppressant agent should be present in an
amount of about 10 to about 60 weight percent of the total composition.
The essential feature of the carrier material used in the present
composition is that it be able to be permeated with suppressant agent in
such a fashion that the suppressant agent will be released from the
carrier material over a period of time. This localizes the suppressant
agent and causes the suppressant agent to be released over a period of
time.
Porous minerals, such as vermiculite, perlite and clays, such as kaolinite
and sodium montmorillonite, are examples of effective carrier materials
which may be readily permeated with the suppressant agent. These
materials, when permeated with suppressant agent, particularly gelled
suppressant agent, are capable of adhering to objects.
Hydrated carrier materials, such as the clays described hereinbefore,
Glauber's salt (Na.sub.2 SO.sub.4.10OH.sub.2 O), sodium phosphate
dodecahydrate (Na.sub.2 PO.sub.4.12H.sub.2 O), and the like are already
suppressant agent permeated carrier materials. The chemically combined
water will be released when the hydrated carrier material is dispersed in
the vicinity of a fire.
Porous polymeric resin materials, particularly of the foamed type, such as
"STYROFOAM" polystyrene from Dow Chemical Company, are also effective
carrier materials capable of being permeated with suppressant agent. Other
types of polymeric resins which are suitable for use as carrier materials
include polyethylene, polyurethane, polyvinylidene fluoride, silicone
polymers, such as methyl vinyl polysiloxane available from General
Electric Company, and the like. These porous polymeric resins adhere to
the surface of an object by forming a melted adhesive coating on the hot
surface of the object.
Where certain polymers, such as polyurethane, are flammable, suitable fire
retardant additives may be added. Suitable fire retardant additives to the
carrier material include decabromodiphenyl oxide and tetrabromophthalic
anhydride, for example. Additionally, fire retardant materials, such as
"Phosgard C-22-R", a chlorinated phosphorous polymer available from
Monsanto Industrial Chemicals Company and "ABS Kynar", a fire retardant
polyvinylidene fluoride available from Pennwalt Corporation, may be used
as the carrier material.
Another type of carrier material adheres to combustible objects, such as
textiles, by physical entanglement. This type of carrier material includes
the small hook members made of nylon sold under the trademark "VELCRO" by
Velcro Inc., and naturally occurring burrs, such as the seed pod of the
cocklebur plant. The small hooks and barbs may be permeated with
suppressant agent. The "VELCRO" hooks will not absorb the suppressant
agent, but are sufficiently small and close together so that the
suppressant agent, and particularly gelled suppressant agent, will cling
to and coat them. This is within the definition of "permeate". The small
hooks and barbs will then adhere to a combustible textile by becoming
entangled within the textile fibers.
Another effective carrier material for use in the composition according to
the present invention includes magnetic materials, such as magnetite or
perforated hollow magnetic beads. The suppressant agent can permeate the
pores of the naturally occurring magnetite or be contained within the
hollow magnetic bead. This type of carrier material magnetically adheres
to a magnetic object in the vicinity of the fire, such as engine
compartment walls of vehicles.
A particularly effective persistent fire suppressant composition results
when the carrier material permeated with the suppressant agent is at least
partially coated with a thermoplastic polymeric resin, such as
polyvinylidene fluoride, "ABS Kynar", silicone polymer, etc. The permeated
carrier material adheres to a hot surface in the vicinity of the
combustion by means of the melted adhesive characteristics of the
polymeric coating. The coating may be applied before or after the
suppressant agent permeates the carrier material. This provides for a
suppressing action which persists over a longer period of time.
The carrier material preferably has a size where the average maximum
dimension of the carrier material is about 0.02-0.25 inch. Carrier
materials in this size range may be readily and stably suspended in a
thixotropically gelled dispersant, are capable of being projected great
distances and have suitable settling times to adequately coat objects in
the vicinity of the combustion. Carrier materials having an average
maximum dimension between about 0.02 and 0.05 inch are particularly
preferred. The carrier material should be present in an amount of about 3
to about 40 weight percent of the total composition.
The dispersant used to propel the suppressant impregnated carrier material
to the vicinity of the fire should be nonflammable, should have fire
extinguishing capabilities and should have a vapor pressure greater than
14.7 psi absolute at ambient conditions. The dispersant is preferably a
liquefied gas which can be thixotropically gelled. Fire extinguishing
dispersants which may be thixotropically gelled include
bromotrifluoromethane, perfluorocyclobutane, bromochlorodifluoromethane,
fluorotrichloromethane and dichlorodifluoromethane, for example. The fire
extinguishing dispersant should be present in an amount of about 10 to
about 60 weight percent of the total composition.
The other essential component of the compositions according to the present
invention is a gelling agent in an amount effective to thixotropically gel
the suspension of permeated carrier material and dispersant. Generally,
about 0.5 to about 5% of the composition should be gelling agent. Suitable
gelling agents include, for example, pyrogenic silica derived from the
combustion of silicon tetrachloride, such as that commercially available
under the trademark "Cab-O-Sil" from Cabot Corp., organo modified
montmorillonite clay (a tetraalkyl ammonium smectite) of the type
available from N.L. Industries, Inc. under the trademark "BENTONE 38",
oleophilic vinyl addition polymer (lightly cross-linked) of a type
available from Dow Chemical Company under the trademark "XVS00100.000",
and other submicron salts well known to those skilled in the art.
The gelling agent is used to make the composition according to the present
invention thixotropic, whereby the composition acts as a liquid when
subjected to mechanical stress, as would occur during filling and
dispensing from containers, and returns to the gel form when at rest, as
when the composition is being stored. The thixotropic fire suppressant
composition should have a yield stress sufficiently high to prevent
settling, compacting and agglomeration of the permeated carrier material
and any additives, yet be sufficiently low to provide for ready
liquefication of the gel during transportation and dispensing. A suitable
yield stress would be between about 20 and 500 dynes/cm.sup.2, a yield
stress of 200 dynes/cm.sup.2 being particularly preferred.
If desired, a gelling agent may be added to the suppressant agent in an
amount effective to thixotropically gel the suppressant agent before and
after it permeates the carrier material. This is particularly desirable
when the carrier material is of a type which does not have a large surface
area to retain a substantial amount of un-gelled suppressant agent. It is
contemplated that a thixotropically gelled suppressant agent would be most
suitable for use with carrier materials comprising hollow, perforated
beads, the small hook members and the burrs.
Additional fire extinguishing additives may be incorporated into the
thixotropically gelled composition. These provide the fire extinguishing
dispersant with additional ability to immediately extinguish fires, after
which the persistent permeated carrier material acts to suppress
reignition of the fire. These agents may include the well known powdered
alkali metal carbonates and bicarbonates, such as sodium carbonate,
potassium carbonate, sodium bicarbonate and potassium bicarbonate,
antimony oxide, ammonium phosphate, tetramethylthiuram disulfide, and the
like. These additives are retained as a stable suspension in the
thixotropic gel.
Evaporation tests of Freon 114B2 permeated in vermiculite compared to an
equivalent amount of Freon 114B2 by itself showed that the permeated
suppressant agent evaporated in about fifteen minutes compared to about
three minutes for the suppressant agent by itself. Thus, it is believed
that the suppressant action will persist about five times longer with the
permeated suppressant agent. Compositions according to the present
invention wherein the suppressant permeated carrier material is coated
with a polymeric resin are believed to be capable of much longer
persistency. The time of effective suppression depends upon the amount of
the composition applied to a fire, the type of fire, the type of surfaces
to which the permeated carrier material adheres, the temperature in the
area and other variable factors. The compositions according to the present
invention may be used preventively by dispersing the compositions in the
path of an oncoming fire in addition to their use to extinguish a fire and
to suppress its reignition.
The compositions according to the present invention may be stored and
dispensed from any suitable container capable of withstanding the
pressures generated by the gelled liquefied gas dispersant. Such
containers are well known to those skilled in the art, and include, for
example, those of the type disclosed in U.S. Pat. No. 3,402,665 of
Tarpley, Jr. et al.
The present invention will now be described in more detail with reference
to the following specific, non-limiting examples. To aid in understanding
the examples, the ingredients are listed in two groups. The first group,
labeled "Persistent Material" includes the suppressant agent, the carrier
material to be permeated by the suppressant agent and, where applicable,
the gelling agent for the suppressant agent. The second group, labeled
"Extinguishing Dispersant" includes the fire extinguishing dispersant, the
gelling agent for the dispersant and additives, if any.
EXAMPLE 1
______________________________________
Ingredient Weight Percent
______________________________________
Persistent Material
chopped polyurethane
21.0
foam particles
1,2-dibromotetrafluoroethane
24.0
Extinguishing Dispersant
bromotrifluoromethane
53.5
colloidal silica 1.5
______________________________________
The foam particles are placed in excess suppressant agent,
1,2-dibromotetrafluoroethane, and the mixture is stirred. The chopped foam
particles are maintained in contact with the suppressant agent with
stirring until the suppressant agent permeates the particles. This may be
determined by weighing the particles after mixing them in the suppressant
agent for various periods of time. When the weight of the particles after
draining the excess suppressant agent is constant, the suppressant agent
is considered to have fully permeated the carrier material.
The gelling agent, colloidal silica, is added to the fire extinguishing
dispersant, bromotrifluoromethane, in a vessel within a pressure chamber.
The drained permeated carrier material is then thoroughly mixed in with
the gelled dispersant. The thixotropically gelled composition is then
placed within a dispensing container within the pressure chamber and
sealed before being removed from the chamber.
Example 2 illustrates a composition according to the present invention
wherein a fire extinguishing powder, KHCO.sub.3, is also suspended in the
gelled dispersant. Otherwise, the method is the same as Example 1.
EXAMPLE 2
______________________________________
Ingredient Weight Percent
______________________________________
Persistent Material
chopped polyurethane
11.0
foam particles
1,2-dibromotetrafluoroethane
14.0
Extinguishing Dispersant
bromotrifluoromethane
53.5
colloidal silica 1.5
KHCO.sub.3 20.0
______________________________________
The method of making the compositions illustrated in Examples 3-5 is
basically the same as the method of Example 1.
EXAMPLE 3
______________________________________
Ingredient Weight Percent
______________________________________
Persistent Material
methyl vinyl polysiloxane
6.0
(porous)
1,2-dibromotetrafluoroethane
34.0
Extinguishing Dispersant
bromochlorodifluoromethane
58.3
colloidal silica 1.7
______________________________________
EXAMPLE 4
______________________________________
Ingredient Weight Percent
______________________________________
Persistent Material
polyvinylidene fluoride resin
5.0
(porous)
1,2 dibromotetrafluoroethane
35.0
Extinguishing Dispersant
bromotrifluoromethane
57.3
Bentone 38 2.7
______________________________________
EXAMPLE 5
______________________________________
Ingredient Weight Percent
______________________________________
Persistent Material
vermiculite 3.0
tetrachlorodifluoroethane
37.0
Extinguishing Dispersant
bromotrifluoromethane
58.3
colloidal silica 1.7
______________________________________
EXAMPLE 6
______________________________________
Ingredient Weight Percent
______________________________________
Persistent Material
vermiculite 3.0
dibromodifluoromethane
37.1
polyvinylidene fluoride resin
0.5
(coated on permeated
vermiculite)
Extinguishing Dispersant
bromotrifluoromethane
58.9
Dow XVS00100.000 0.5
______________________________________
The composition illustrated by Example 6 is prepared in a manner similar to
the preparation of the compositions illustrated in the previous examples,
except that before the dibromodifluoromethane permeates the vermiculite,
the vermiculite is partially coated with the polyvinylidene fluoride. The
vermiculite particles are partially coated by contacting a portion of the
surface of the particles with molten resin. The partially coated permeated
material is then suspended in the thixotropically gelled dispersant as
before.
Examples 7-10 illustrate the use of a gelled suppressant agent which
permeates the carrier material, in Example 7 a naturally occurring seed
pod. Dry fire extinguishing powder, NH.sub.4 H.sub.2 PO.sub.4, is also
added to the thixotropically gelled dispersant in Example 7.
EXAMPLE 7
______________________________________
Ingredient Weight Percent
______________________________________
Persistent Material
cocklebur 4.0
bromochloromethane 21.0
colloidal silica 0.5
Extinguishing Dispersant
bromotrifluoromethane
53.0
colloidal silica 1.5
NH.sub.4 H.sub.2 PO.sub.4
20.0
______________________________________
EXAMPLE 8
______________________________________
Ingredient Weight Percent
______________________________________
Persistent Material
"VELCRO" hook members
4.0
1-2,-dibromotetrafluoroethane
53.2
colloidal silica 1.5
Extinguishing Dispersant
bromotrifluoromethane
40.0
colloidal silica 1.3
______________________________________
EXAMPLE 9
______________________________________
Ingredient Weight Percent
______________________________________
Persistent Material
porous magnetite 17.3
1,2-dibromotetrafluoroethane
40.0
colloidal silica 1.4
Extinguishing Dispersant
bromotrifluoromethane
40.0
colloidal silica 1.3
______________________________________
EXAMPLE 10
______________________________________
Ingredient Weight Percent
______________________________________
Persistent Material
hollow perforated magnetic
32.0
iron beads
1,2-dibromotetrafluoroethane
16.0
colloidal silica 0.5
Extinguishing Dispersant
bromotrifluoromethane
50.0
colloidal silica 1.5
______________________________________
The hollow magnetic iron beads used as the carrier material in Example 10
are perforated. The beads are mixed in a pressure chamber with the gelled
1,2-dibromotetrafluoroethane and the pressure in the chamber is then
increased to drive the gelled suppressant agent into the interior of the
beads, since the pressure in the interior of the beads is less than the
increased pressure. The permeated beads are suspended in the
thixotropically gelled dispersant and placed in a container as in the
other examples.
The present invention may be embodied in other specific forms without
departing from the spirit or essential attributes thereof and,
accordingly, reference should be made to the appended claims, rather than
the foregoing specification as indicating the scope of the invention.
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