KR20070085736A - Methods for preventing and/or extinguishing fires - Google Patents

Abstract

In the prevention of the spread of fires and for directly fighting fires, a cross-linked, water-swellable additive polymer in a vegetable oil dispersion is added to firefighting water. The additive has the properties of absorbing large quantities of water, high viscosity for adherence to vertical and horizontal surfaces, and retention of sufficient fluidity to be educted in standard firefighting equipment. The method of adding this additive to the firefighting water by eduction, pumping, or batch addition to the source water is also disclosed.

Description

Fire protection and / or extinguishing methods {METHODS FOR PREVENTING AND / OR EXTINGUISHING FIRES}

FIELD OF THE INVENTION The present invention generally relates to fire protection and / or extinguishing methods, and more particularly to a method of applying water-containing polymer particles to a surface to prevent and / or extinguish a fire.

Water is generally used to extinguish fire and to prevent the spread of fire to nearby structures. Water has several beneficial effects, including removal of heat and depletion of oxygen when applied to fire. When water is directed to structures near the fire to prevent the propagation of the fire, the fire generates enough heat to evaporate water on the adjacent structure (or material within it) before the adjacent structure reaches its combustion or ignition temperature. Must be provided.

One disadvantage of using water to prevent fire propagation to nearby structures is that most of the water destined for the structure does not penetrate inside the structure to provide fire protection, but rather runs off from the structure to the ground. ) Tends to. As a result, a significant amount of water is wasted. Another disadvantage is that any water seeping into the structure provides only a limited defense against fire, since most structures only absorb a limited amount of water, and a limited amount of absorbed water quickly evaporates. to be. Therefore, considerable manpower must be consumed in order to continuously supply water to nearby structures to prevent fire continuously.

The disadvantage of using water to extinguish a fire is that a significant amount of water does not directly extinguish or extinguish the fire due to the run-off problem described above. Another disadvantage of using water in extinguishing a fire is that water sprayed directly into the fire evaporates at the upper level of the fire, resulting in significantly less water than the base supplied. penetrates enough to extinguish the fire.

In order to alleviate the above drawback of using water (itself) to extinguish a fire, U.S. Patent No. 5,190,110 to von Blucher et al. Discloses an aqueous solution containing a dry absorbent polymer to extinguish and / or prevent fire. Disclosing the use of the system. The polymer particles have a particle size of 20 to 500 μm and are dispersed in water by stirring or pump so that the resulting viscosity does not exceed 100 cps (centipoise). The system includes discrete polymer particles that do not dissolve in water and absorb water. Thus, the particles are included in the water so that they are applied directly to the fire. The dried solid granular particles are generally premixed with the water source. On the other hand, the dried solid granular particles may also be added directly before the nozzle. Since this other method does not provide sufficient time for the particles to expand, the resulting viscosity does not increase enough to allow the particles to adhere to the surface.

U. S. Patent No. 4,978, 460 to this Blueshire et al. Also discloses the use of an aqueous system comprising a dry absorbent polymer to extinguish and / or prevent fire. The dried solid polymer particles of U.S. Patent No. 4,978,460 are wrapped with a water soluble release agent to prevent agglomeration of the particles. The time required for the encapsulated solid granular particles to swell (ie, absorb water and swell) ranges from 10 seconds to several minutes. When extinguishing a fire with a hose of typical length, 10 seconds is longer than the actual time the water is kept in the fire hose. Thus, when such wrapped polymer particles are used with standard fire-fighting devices, there is not enough time for the particles to expand, and the viscosity does not increase enough to allow the particles to adhere to the surface.

Zweigle, US Pat. No. 3,758,641, also discloses the use of dried solid granular polymer particles with high moisture absorption when applied to firefighting. The particles disclosed above are best achieved when used with special additional fire suppression apparatus.

Because of the dry solid granular nature of the water-absorbing polymer particles for conventional firefighting described above, it is not possible, but difficult, to use such polymers in many firefighting applications. For example, it is almost impossible to introduce such a polymer into a standard firefighting hose in a standard device because of the particulate nature of such a polymer. In addition, the dry, solid nature of the polymer promotes agglomeration of the particles and prevents water from flowing sequentially from the firefighting hose. Thus, in order to use the dried solid granular particles in fire suppression applications, it is sometimes necessary to provide special devices such as "pumps and spray nozzles adapted to handle such materials" (e.g., See Zweigle, US Pat. No. 3,758,641).

In addition, if a natural source of water, such as a tributary or a river, is used as the water source, it is not possible to premix the polymer by batch addition to the water source. For example, if the polymer additive is poured into a stream or river, most of the polymer additive will simply flow past the point of inhaling water for the purpose of fighting a fire.

The present invention provides vegetable oil dispersions comprising dried powdered crosslinked water-expandable polymers for use in the prevention and / or extinguishing of fires. Advantageously, the dispersion is easily mixed with a water supply. In addition, the dispersion can provide a water-additive mixture having a sufficiently high viscosity to combine with water and immediately adhere to vertical and horizontal surfaces in functional thickness. In addition, the polymer included in the dispersion has a very short expansion time (to absorb water) and is immediately educted into the fire hose by using standard fire suppression equipment. In addition, since the dispersion of the present invention includes vegetable oil, using it as an additive for extinguishing fire is environmentally friendly when compared to mineral oil emulsion-based polymers.

In one embodiment of the invention, a method of applying polymer particles to a surface to prevent and / or extinguish a fire comprises providing crosslinked polymer particles in the form of a vegetable oil dispersion; Adding the dispersion as a water-absorbent additive to water in an amount sufficient to increase the viscosity of the resulting water-additive mixture above about 100 cps; And directing the additive / water mixture to a surface to prevent and / or extinguish the fire, wherein after absorbing the water, the additive retains at least about 50% by weight of the total water.

In another embodiment of the invention, a method of applying polymer particles to a surface to prevent and / or extinguish a fire adds vegetable oil and dried powdered crosslinked water-expandable polymer to water to form a water-additive mixture. Making; And directing the water-additive mixture to a surface to prevent and / or extinguish a fire, wherein after expansion the polymer retains at least about 50% by weight of water in the water-additive mixture.

The method of the present invention utilizes water additives to prevent and / or extinguish fire. The additive is a dispersion comprising vegetable oil and a crosslinked water-expandable polymer. The dispersion is prepared by dispersing the powdered, dry, water-expandable polymer in vegetable oil, optionally with the appropriate surfactant (s) and stabilizer (s), if necessary or desired. In a preferred embodiment, the dispersion comprises crosslinked polymer dried in vegetable oil, and suitable emulsifier (s) and suspending agent (s).

Preferably, the dispersion is a dried crosslinked polymer of one or more hydrophilic monomers dispersed in vegetable oils. Typically, the polymer is a copolymer of acrylamide and acrylic acid derivatives (eg acrylate salts). Typically, the polymer is a terpolymer of acrylate salts, acrylamides and 2-acrylamido-2-methylpropanesulfonic acid (AMPS) salts. The polymer particles resulting from the polymerization are generally ground to a size of about 74 μm or less, and typically 70% of the particles have a size of 37 μm or less. However, polymer particles having a size in the range of about 10 to about 200 μm may be used.

Virtually any water soluble vegetable oil can be used to prepare the dispersion. Preferably, the vegetable oil is rapeseed oil (or refined form thereof, canola oil).

Gels are typically formed after the dispersion has been added to firefighting water. Selecting the size of the oil and dispersed crosslinked water-expandable polymer particles is determined by the desired flexibility / rigidity of the gel formed after the dispersion is added to the firefighting water. Formation of immobilized gels generally occurs within about 3 seconds; Thus, the particles preferably have an expansion time of about 3 seconds or less. The gel typically has a viscosity of at least about 100 cps, preferably at least about 500 cps to about 500,000 cps. Formation of a "immobilized" gel means that the gel will attach upon contact with the vertical surface.

Low HLB surfactants can be used to aid in the dispersion of dried polymer particles in the vegetable oil. Higher HLB surfactants can be added to the dispersion to modify the flowability of the gel for special fire suppression devices. A particularly suitable low HLB surfactant is sorbitan monooleate. Sorbitan monooleate is used as an emulsifier in foods.

Preferably, the additive is present in an amount sufficient to absorb at least about 50% by weight of the total water after absorbing the water.

Suspending agents such as fumed silica can be used to provide stability and fluidity to the dispersion. This allows the dispersion to be introduced in liquid form into the water supply so that it can be easily discharged into a standard fire suppression apparatus. The use of fumed silica not only provides stability to the dispersion, but also surprisingly increases the stability of the water-additive mixture (gel) and allows the preparation of gels with low concentrations of additives immobilized. Fumed silica is also approved as a direct food additive.

Polymeric dispersions comprising, consisting solely of, or consisting of vegetable oils (e.g. canola oil), sorbitan monooleate and fumed silica, may be used as food ingredients or directly as food additives. It is particularly desirable in terms of health, safety, environment and handling in that it is approved.

The additive is typically added to the water at a concentration of no greater than about 0.1 to about 50 volume percent, usually no greater than about 20 volume percent. Preferably, the additive is added to the water at a concentration of about 0.1 to about 10 volume percent, more preferably about 1 to about 3 volume percent, or about 1 to about 2 volume percent.

The additive absorbs a significant amount of water relative to its size and weight, and characterizes super-absorbent polymers and thickeners in that the resulting water-additive mixture may have a relatively high viscosity. To serve. Thus, the water-additive mixture sprayed from the end of the fire hose immediately attaches to a functional thickness on both the vertical and horizontal surfaces. This attachment prevents fire damage to the structure to which the water-additive mixture is attached for a relatively long time, thereby minimizing the manpower required to recoat the structure. Thus, using such water-additive mixtures to coat structures near fire provides a protective coating to the structures. Thus, the fire will not spread quickly because it must overcome the effects of a significant amount of water present in the water-laden polymer particles of the additive adhering to the structure. In addition, since the amount of water absorbed by the additive evaporates less quickly than that provided by pure water, using the additive provides more water to prevent and / or extinguish the fire. In addition, the benefits of fire suppression of the additive may be compensated for by misting (for example after coating the structure with the water-additive mixture). Misting is typically performed when a portion of the water retained by the polymer evaporates.

The method of adding such additives to the firefighting water is preferably through eduction into the feed water, pumping, or batch addition. The nature and properties of the additives enable discharge through standard fire suppression apparatus.

As shown in FIG. 1, the additive may be discharged into the fire hose 10 in any suitable manner as is presently used to discharge fire suppressing blowing agents such as aqueous film-forming blowing agents (AFFF). The trailing hose 12 is located in an additive bucket 14. The flow of water through the fire hose 10 creates a negative pressure at the discharge nozzle 16, which draws the additive from the bucket 14 into the flow of water through the fire hose 10. The discharge nozzle 16 has an internal valve to control the flow of the additive. The additive can be used with existing standard fire suppression apparatus and does not require the purchase of a new apparatus. Since the additive is a flowable dispersion, it is not necessary to add a carrier or release agent such that it can be discharged or mixed.

On the other hand, the additive may be batch added to the water tank 18 on the fire truck 20. Once again, since the additive is a liquid dispersion, it is not necessary to add a separate carrier or release agent to prevent the large scale agitation or aggregation required in the case of solid additives currently used. Only limited mixing is typically required in this batch addition of the additives of the present invention.

When the additive is introduced into a significant amount of fire extinguishing water, such as being discharged into a fire hose or batched into a water tank, the dispersion is mixed with the fire extinguishing water and the polymer particles in the dispersion contain a large volume of water. Exposed to quickly absorb a significant amount of water.

The expanded particles from the vegetable oil dispersion form a homogeneous, very viscous fluid. Because of the nature of the dispersion, the resulting water-additive mixture has a relatively high viscosity with a short (preferably up to about 3 seconds) expansion or absorption time, allowing the mixture to adhere easily to both vertical and horizontal surfaces. In addition, the water-additive mixture has sufficient fluidity so that the additive is easily discharged through a standard fire suppression apparatus.

When the water-additive mixture is sprayed on a vertical or horizontal surface, the mixture adheres to the surface to extinguish the fire and / or provide extended fire protection to a structure located near the fire. As shown in FIG. 2, when the mixture is sprayed onto the surface 22, the water-containing polymer particles 24 accumulate on top of each other. This is similar to the manner in which AFFF and other blowing agents are used, but the polymer particles 24 are contained with water and the traditional blowing agent drops are filled with air. This filling of water significantly improves the thermal defense quality of the additive.

As the fire approaches the surface 22, the outer water-containing polymer particles 24 closest to the fire absorb heat until they reach the vaporization point of the water. Thus, the water-containing polymer particles 24 close to the wall are protected until the outer water-containing polymer particles 24 are vaporized. The water-containing polymer particles 24 of the next layer then absorb heat until they reach the vaporization point of the water, shielding the water-containing polymer particles of the remaining inner layers. This process continues until the innermost layer of water-containing polymer particles 24 are vaporized. This process absorbs heat significantly more effectively than using conventional blowing agents that use air instead of water to absorb heat because water has a significantly higher heat capacity than air bubbles.

In another advantage, depending on the viscosity of the coating gel, the coating on the surface above the point of fire slips down and partially slides until the fire vaporizes water in the layer of water-containing polymer particles below the protected surface. Recoating, and continue to protect areas penetrated by fire. It also minimizes the manpower and material sources currently needed to periodically re-immerse the surface. Obviously, at some point a continuous fire will evaporate substantially all the water in the additive. However, by delaying the spread of fire and the damage caused by the fire, and by using the additive directly to extinguish the fire, firefighters will be able to fight the weakened fire much more effectively, and the damage caused by the fire will cause It will be much less than the damage that occurs when conventional firefighting techniques and materials are used to extinguish. Thus, the additive represents a significant leap forward in firefighting technology.

As mentioned above, when water is sprayed directly onto a fire, much of the water never effectively extinguishes the fire because the superheated air above the fire evaporates the water before it reaches the flame. However, when the additive of the present invention is used, more water reaches the fire because the water-containing additive polymer particles delay the evaporation, which slows down the evaporation process. Thus, not only does more water reach fire, but less water is used than simply using water, or even when using conventional additives such as fire fighting blowing agents.

In addition, when simply applying water, a significant portion of the water directly applied to the fire (and not evaporated) flows down or seeps into the ground and is thus discarded after the first application. As a further advantage, the water-additive mixture of the present invention also coats ash or burning charred structures instead of flowing down or seeping into the ground, wherein the water-containing polymer particles are capable of absorbing heat and being viscous. The mixture adheres to the surface and deprives the oxygen of combustion of the surface, thus helping to prevent re-ignition, thus providing the effect of choking the burned surface.

Because of this property of the additive, the water-additive mixture is also suitable for use as an artificial fire break when fighting large or small forest fires. The mixture may be sprayed prior to the fire and may coat structures such as shrubs or trees to stop the progress when the fire reaches the treated area and allow the firefighter to extinguish the flame without further progress of the fire. This significantly reduces damage than using bulldozers or the use of conventional fire protection means such as controlled burning to clear the area for fire protection.

The additive can absorb a significant amount of water than its own weight. Once the additive particles are added to the fire extinguishing water and absorb water at their capacity (preferably within 3 seconds), the particles can carry at least about 90% by weight of the water used for extinguishing the fire.

The polymer is preferably a crosslinked water soluble polymer dried in a vegetable oil dispersion. The polymer may be acrylamide, acrylic acid derivatives, maleic anhydride, itaconic acid, 2-hydroxyethyl acrylate, polyethylene glycol dimethacrylate, allyl methacrylate, tetraethylene glycol dimethacrylate, triethylene glycol dimethacrylate. Methacrylate, diethylene glycol dimethacrylate, glycerol dimethacrylate, hydroxypropyl methacrylate, 2-hydroxyethyl methacrylate, 2-tert-butyl amino ethyl methacrylate; Hydrophilic monomers and other hydrophilic monomers such as dimethylaminopropyl methacrylamide, 2-dimethylaminoethyl methacrylate, hydroxypropyl acrylate, trimethylolpropane trimethacrylate, 2-acrylamido-2-methylpropanesulfonic acid derivatives It may be a polymer of. Preferably, the polymer is a copolymer of acrylamide and acrylic acid derivatives, more preferably terpolymers of acrylate salts, acrylamides and 2-acrylamido-2-methylpropanesulfonic acid (AMPS) salts. The salt may generally be any monovalent salt, but is preferably a sodium or potassium salt.

Many such dried polymers are commercially available and are routinely used in diapers. Viscosities significantly greater than 100 cps, even in the range of 500 to 50,000 cps, are readily available and can be advantageously used for the additives of the present invention. This is in contrast to the state of the art disclosed in U.S. Patent No. 5,190,110 to this Blueshire et al., Which discloses that viscosity of 100 cps or higher is undesirable and not handleable in firefighting. A higher viscosity of the water-additive mixture allows the water-additive mixture to adhere better to the vertical surface, but the water-additive mixture still has sufficient fluidity so that the additive can be successfully discharged through a standard fire suppression apparatus. Can be.

Since the degree of hardness of the water, i.e. the amount of divalent cations in the water, affects the degree of expansion of the polymer particles, components for counteracting the hardness of water can also be introduced. Suitable monomers for offsetting the hardness of water in the present invention are AMPS or derivatives thereof. The amount of AMPS contained in the dry polymer will vary depending on the hardness of the water in the particular region used. Nevertheless, the polymers are effective without the inclusion of chemicals to counteract the hardness of the water, especially in the geographical area without hard water.

The size of the polymer particles in the dispersion is generally no greater than 74 μm and 70-95% of the particles are generally no greater than about 37 μm in size. The particle size of the polymer has a preferred expansion time of about 3 seconds or less, so that the particles complete their expansion for a time that the additive / water mixture is fixed on the surface to be protected from when the additive is discharged into the fire water. . Since they are dispersed in vegetable oil / surfactant systems, the particles in the additives of the present invention will preferably have an expansion time of about 3 seconds or less, while the expansion time of conventional polymer particles is at most about 10 seconds (eg For example, US Pat. No. 4,978,460 to the present Blueshire et al.). Conventional polymer particles often have an expansion time of several minutes or even hours before absorbing sufficient water suitable for use in firefighting (see, eg, US Pat. No. 3,247,171 to Walker et al.). Such long expansion times are unsuitable for use in exhaust systems without very improved manufacturing and / or special equipment.

Because of the short expansion time and fluid state of the additives of the present invention, the additives are best suited for use in standard discharge systems with fire hoses and water sources such as tanker trucks or fire hydrants. This eliminates the need for a special device for implementing the method of the present invention. The invention is also suitable for use by adding the additive directly to the tank of the tanker truck. For this purpose, only 10-15 gallons of additives (ie less than 130 pounds) are needed to process a standard 500 gallon tank on a fire tanker truck. This requires 200 g of additive per 1 liter of water, which is a significant improvement over the state of the art disclosed in US Pat. No. 4,978,460 to the present Blueshire et al., Which is equivalent to about 835 pounds for a typical 500 gallon tank.

1 illustrates a typical device used to apply polymer particles to a surface to prevent and / or extinguish a fire.

2 is a schematic diagram illustrating an embodiment of the invention.

Several tests were performed to evaluate the fire suppression and fire protection properties of the additive.

Example  One

A 4 foot by 4 foot plywood sheet, 1/4 inch thick, was coated with product 4 of Table 1 to approximately 1/4 inch thick using a discharge tube with 2.5% by volume of water-additive mixture solution. After this application, the plywood was subjected to an open flame created by a propane gas jet. The time at which the treated plywood was burned through was measured and compared to the melt time of the same untreated plywood sheet. The melt time of the treated plywood was 9 minutes 12 seconds. The melt time of the untreated plywood was 2 minutes 40 seconds.

Example  2 to Example  7. Comparison of fire protection

Discharging the additive into the fire water stream does not guarantee the correct concentration of the additive nor does it allow for the correct gel coating thickness. In order to make an accurate retardant comparison of additive concentration, gel thickness and vertical surface stability, experiments were conducted to adjust these parameters. A series of additives of the correct concentration were prepared at low speed in a blender that simulates ejector manufacture. A 1/4 inch thick poplar plate was coated with the correct coating thickness (using draw-down technology). In addition, accurate propane flame heat and impingement distances were used. In all cases, gels prepared in the blender from the additive / water mixture and used in this test were fixed within 3 seconds. The gel was then spread over the poplar plate in the thicknesses shown in Table 1 and tested as above.

product type Concentration of the product (vol%) required to make a stable, fixed gel coating in the vertical Coating thickness (inch) Melt time of gel coating Total time to melt 1/4 "plate (minutes: seconds) No coating (control) - - - (One) 2:24 (2) Mineral oil-based emulsion 3.5% 1/4 " 2:45 5:28 (2A) Mineral oil based emulsion + 2% fumed silica 3.5% 1/4 " 3:06 5:40 (3) Dried Polymeric Dispersion 4.0% 1/4 " 2:40 5:10 (4) 3.5% 1/4 " 4:11 7:00 (4) 3.0% 1/4 " 4:04 6:40 (4) 2.5% 1/4 " 2:46 5:48 (4) 3.0% 1/8 " 2:05 4:50 (5) 3.5% 1/4 " 3:41 6:38 (6) 3.0% 1/4 " 3:50 5:46 (7) 2.0% 1/4 " 2:30 5:30

Reference notes:

(1) The surface of the control plate was flamed within 11 seconds and melted within 2 minutes and 24 seconds.

(2) Mineral oil-based commercial tanning fire suppression product, active polymer content of 38% by weight.

(2A) Add 2% by weight fumed silica (CAB-O-SIL EH-5) to (2).

(3) Dried polymer dispersion: 38.9 wt% powdered dry polymer (99.9% of dry polymer of 74 μm or less, 94.5% of 44 μm or less, 90% of 37 μm or less), 2.4 wt% sorbitan monooleate (Span 80), 58.7% by weight canola oil.

(4) Dried polymer dispersion: 38.2% by weight dry powder (dry polymer of the same size as above (3)), 2.3% by weight sorbitan monooleate, 1.7% by weight fumed silica (CAB-O-SIL EH-5), 57.8 wt% canola oil.

(5) Dried polymer dispersion: 38.0% by weight powdered dry polymer (dry polymer of the same size as (3) and (4) above), 2.3% by weight sorbitan monooleate (Span 80), 0.6% by weight High HLB surfactant (Dow XL-80N), 1.7 wt% fumed silica (CAB-O-SIL EH-5), 57.4 wt% canola oil.

(6) Dried Polymeric Dispersion: 38.2% by weight powdered dry polymer (99.8% of dry polymer of 74 μm or less, 82.9% of 44 μm or less, 73.4% of 37 μm or less), 2.3 wt% sorbitan monooleate (Span 80), 1.7 wt% fumed silica (CAB-O-SIL EH-5), 57.8 wt% canola oil.

(7) Dried Polymeric Dispersion of the Invention: 39.1 wt.% Dry powder (same size as (3), (4) and (5) above), 1.8 wt.% Fumed silica (CAB-O-SIL EH -5), 59.1 weight% canola oil.

The data in Table 1 above shows the surprising performance of fire fighting gels prepared from the dry polymer-containing products of the present invention. Product 4, a micro-powdered dried polymer in canola oil that includes a low HLB emulsifier and fumed silica, provides fire protection superior to product 3 of the same formulation, except that fumed silica is absent. In addition to providing stability to the dispersion, the presence of fumed silica surprisingly stabilizes the gel formed when the dispersion is added to the firefighting water, and surprisingly the concentration of gel coating required to adhere to vertical surfaces. To reduce. This not only requires a low concentration of dispersion to produce a vertically stable gel, but also means that the water available in the gel is increased to extinguish the fire at a given gel thickness.

For comparison, a commercial mineral oil based emulsion product (Product 2) was tested. Product 2 has less fire protection than product 4 of the present invention. In addition, the viscosity of the mineral oil based formulation of Product 2 is not significantly improved (in product 2A) by the addition of fumed silica to reduce the concentration. The increased gel stability imparted by fumed silica with the vegetable oil (actually a naturally occurring fatty acid ester) carrier in the dispersion of the present invention provides significant and unexpected benefits.

As disclosed in US Pat. No. 6,245,252 B1 (column 7, line 19), emulsion polymers prepared by reverse phase polymerization require a high HLB emulsifier to rapidly “invert” the emulsion. The inverting emulsifier emulsifies the oil-continuous-phase into dilution water and exposes the polymer particles to water so that they can expand. In the present invention using vegetable oils, ie fatty acid esters, inverting surfactants, often referred to as wetting agents, are not required to produce very stable gels quickly.

Another surprising result is that the addition of humectant (high HLB surfactant) in product 5 does not adequately reduce the time for gel formation (all tested products form gels within about 3 seconds). In addition, the addition of a high HLB surfactant reduces the viscosity of the gel to an extent that its concentration cannot be reduced to the extent possible with product 4, a product without high HLB, and still maintains a stable vertical coating. The combination of the dried powdered polymer in vegetable oils, including low HLB surfactant with water and fumed silica, produces a soft and homogeneous gel that is a very effective fire suppression product. For the low HLB surfactant (Product 7), a 2% by volume concentration will produce a vertically stable gel, but the coating is not as homogeneous, and a concentration above 2.5% by volume becomes friable. Adjustments in the application will be difficult using ejector nozzles.

Product 6 shows that even thicker, coarse powdered dried polymers can be used, but the vertical gel stability is somewhat lost, showing that a slightly higher gel concentration is required compared to product 4.

In application, the additive may be provided in a 1 gallon or 5 gallon container when used in a standard discharge system. The concentration of the additive for the discharge is preferably between 0.1 and 10% (volume to volume), but concentrations up to 20% by volume may be acceptable. If the concentration is significantly above 20% by weight, the viscosity of the water-additive mixture often becomes unwieldy. Likewise, for use in direct mixing into the tank, the additive is preferably batch mixed at a concentration between 0.1 and 10% by volume, but concentrations up to about 20% by volume are acceptable. Additive concentrations of about 1.0 to about 3.0 volume percent provide suitable properties for fire suppression, and higher concentrations are generally unnecessary. Use of low concentrations also improves cost efficiency.

Claims (21)

A method of preventing and / or extinguishing a fire by applying water-containing polymer particles to a surface, the method comprising (a) adding a dispersion comprising a vegetable oil and a dry powdered crosslinked water-expandable polymer to water to form a water-additive mixture comprising water-containing polymer particles, wherein the polymer is expanded after At least about 50% by weight of the water in the water-additive mixture; (b) preventing the fire and / or extinguishing the water-additive mixture towards the surface. The method of claim 1, Wherein said dispersion further comprises at least one additive selected from the group consisting of surfactants and stabilizers. The method of claim 1, The dispersion is added in an amount sufficient to increase the viscosity of the water-additive mixture above 100 cps. The method of claim 1, Said vegetable oil is selected from the group consisting of rapeseed oil and canola oil. The method of claim 1, Said polymer having a particle size in the range of about 10 to about 200 μm. The method of claim 2, Wherein said surfactant has a net hydrophobic / lipophilic balance (HLB) value of about 8 or less. The method of claim 1, Adding a surfactant having a net HLB value of about 8 or greater to the dispersion to modify the flow characteristics of the water-additive mixture. The method of claim 2, Wherein said stabilizer is fumed silica. The method of claim 1, Said addition comprising discharging said dispersion into water with a standard fire suppression apparatus. The method of claim 1, The addition comprises batch-adding the dispersion to the water. The method of claim 1, The polymer has an expansion time of about 3 seconds or less. The method of claim 1, Wherein said dispersion is added in an amount sufficient to increase the viscosity of said water-additive mixture to about 500 to about 50,000 cps. The method of claim 1, The polymer is formed from a hydrophilic monomer. The method of claim 13, Wherein said hydrophilic monomer is selected from the group consisting of acrylamide and acrylic acid derivatives. The method of claim 14, Wherein said acrylic acid derivative is an acrylate salt. The method of claim 1, The polymer is a terpolymer of an acrylate salt, acrylamide and 2-acrylamido-2-methylpropanesulfonic acid salt. The method of claim 1, And the concentration of the dispersion of said water-additive mixture is between about 0.01 and about 50 volume percent. The method of claim 1, And wherein the concentration of the dispersion of said water-additive mixture is between about 0.1 to about 10 volume percent. The method of claim 1, And wherein the concentration of the dispersion of said water-additive mixture is between about 1 and about 2 volume percent. The method of claim 1, Directing the water-additive mixture to a surface and then misting the water-additive mixture. The method of claim 20, Performing the misting when a portion of the water retained by the polymer evaporates.

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