Water additive and method for fire prevention and fire extinguishing

Abstract: In the prevention of the spread of fires and for directly fighting fires, a cross-linked, water-swellable additive polymer in water/oil emulsion produced by an inverse phase polymerization reaction to be added to the firefighting water is disclosed. The additive has the properties of absorbing large quantities of water, high viscosity for adherence to vertical and horizontal surfaces, and retention of suffizient fluidity to be educted in standard firefighting equipment. The method of adding this additive to the firefighting water by eduction or by a batch addition to the water source is also disclosed.

Description: Background of the Invention The present invention relates to methods involving the use of water additive in fire prevention and fire extinguishing. The primary component of the additive is a cross-linked polymer with thickening properties. Water is the most commonly used substance to extinguish fires and to prevent the spread thereof to surrounding structures. Water has several effects on a fire, such as heat removal and oxygen deprivation. When structures adjacent to a fire are soaked with water, the fire must provide enough heat to evaporate the water before the structure can reach its combustion or ignition temperature. A significant disadvantage to the use of water to soak adjacent structures is that the water that does not soak into the structure tends to run off or fall unused upon the ground, thus wasting the water. Another disadvantage is that the water that does soak into the structure provides only a very limited protection against the fire because the structure may only absorb a limited amount of water, and that water is quickly evaporated. Also, significant manpower must be expended to resoak those structures from which the water is evaporated to provide continuing fire protection. A further disadvantage to using water in fighting fires is that a significant amount of the water does not directly fight the fire because of the aforementioned runoff. Another disadvantage to using water in fighting fires is that water sprayed directly on the fire evaporates at an upper level of the fire, with the result that significantly less water than is applied is able to penetrate sufficiently to extinguish the base of the fire. To address the above disadvantages with water, US 5,190,110A, issued to von Blücher et al, uses absorbent polymers with particle sizes from 20 to 500 microns dispersed in a water miscible media to be incorporated into the water by stirring or pumping, such that the resultant viscosity does not exceed 100 mPa·s. This system contains discrete gel particles that absorb water, without being soluble in water, and are entrained in the water for application directly to a fire. The '110 patent teaches directly away from using any materials that result in a higher viscosity than 100 mPa·s. The usual method of applying the additive in the '110 patent is to pre-mix the solid granule particles with the water source. An alternative method that is disclosed is to add the solid granule particles directly in advance of the nozzle while they are in the non-swollen condition. This alternative does not provide sufficient time for the particles to swell, and the viscosity is not increased sufficiently to allow the particles to adhere to surfaces. This is akin to just throwing the solid polymer particles on the fire in the hopes that they will swell after application. Likewise, US 4,978,460A, issued to von Blücher et al, addresses the problem of using solely water to extinguish fires. The solid polymer particles of the '460 patent are encased by a water-soluble release agent to avoid any agglutination of the particles. The time that it takes for these solid granular particles to expand from the absorption of water ranges from ten seconds to several minutes. When fighting a fire with typical hose lengths, ten seconds is longer than practical for the water to be retained in a fire hose. Additionally, in order to achieve the desired water absorption, it was necessary to introduce 200 grams of the product of the '460 patent into each liter of water. At this rate, approximately 835 pounds (378 kg) of the product would be required for a typical 500 gallon (1894 liter) pumper. US 3,758,641A, issued to Zweigle, also discusses the use of solid granular polymer particles with high water absorption in firefighting applications. Use of these particles is best accomplished with special, additional firefighting equipment. The state of use of absorbent polymers in fighting fires remains that due to the solid, granular nature of the particles, it is difficult, if not impossible, to use these polymers in many firefighting applications. For example, if a natural source of water, such as a creek or a river, is to be used as the water source, it is impossible to pre-mix the polymer and batch add it to the water source, as necessary in traditional applications, in order to draw it off to use to combat fires. By pouring the additive into a stream or river, most of the additive will simply flow past the point of suction of the water for use in combating fires. Likewise, because of the particulate nature of the stateof-the-art firefighting, water-absorbent polymer, eduction of such polymer into the standard firefighting hose with standard equipment is nearly impossible. The solid nature of the polymers promote agglutination of the particles and subsequent blockage of the flow of the water. Alternatively, it is also sometimes necessary to provide "pumps and spray nozzles adapted for handling for such materials" in the use of these solid granular particles (see, for example, Zweigle '641 ). Additionally, the smallest particle size disclosed by the current water-absorbent polymer art for use in firefighting is no less than 20 microns. Thus, it becomes desirable to develop a water-absorbent polymer that is not limited in application, as are the above polymers, by a solid, granular state. Such a water-absorbent polymer for use as a yarn coating is disclosed in US 5,264,251A, issued to Geursen et al (EP-A-0 482 703). The polymer provided in Geursen provides substantial water absorption and can be processed in stable water-in-oil emulsions. Such an emulsion allows this absorbent polymer material to be applied to a yarn. It is important for the polymer formed in such a water-in-oil emulsion in the Geursen patent to retain a relatively low viscosity. This is critical to the application of the polymer to the yarn. Thus, it would be desirable to provide a water-absorbent polymer that will quickly swell in the presence of water for application in firefighting situations. Such a composition would be mixable with the water source and desirably be eductable into a fire hose using standard firefighting equipment to allow its use in a very wide variety of firefighting situations, and also have sufficient viscosity to enable it to adhere to vertical and horizontal surfaces. Summary of the Invention It is an object of the present invention to provide methods involving the use of a water additive in fire prevention and fire extinguishing that has the characteristics of a highly water-absorbent polymer that is easily mixed with the water supply for fighting fires and, when combined with water, results in a water-additive mixture with sufficiently high viscosity that the mixture readily adheres to vertical and horizontal surfaces. According to the present invention, the water additive to be used in fire prevention and fire extinguishing has a very short swell time to absorb the water, and is easily educted into a fire hose through the use of standard firefighting equipment. The additive is comprised of a cross-linked, water-swellable polymer in a water/oil emulsion that is produced by an inverse phase polymerization reaction. Preferably, the water-swellable polymer is a co-polymer of acrylamide and acrylic acid derivatives and, more preferably, the polymer is a terpolymer of neutralized or partially neutralized acrylic acid and 2-acrylamido-2-methylpropanesulfonic acid (AMPS) and acrylamide. The particles resulting from this polymerization are generally less than about one micrometer in size. The particles are dispersed in an oil emulsion wherein the polymer particles are contained within discrete water "droplets" within the oil. With the help of an emulsifier, the water "droplets" are dispersed relatively evenly throughout the water/oil emulsion. This allows the additive to be introduced to the water supply in a liquid form, such that it can be easily educted with standard firefighting equipment. The nature of this additive is such that it is a thickener for the water, and combines this thickening property with a very high water absorption capacity. Thus, the water-additive mixture that is sprayed from the end of a fire hose has a relatively high viscosity and adheres readily to both vertical and horizontal surfaces. This adherence allows the water-additive mixture to prevent the fire from damaging the structure to which it adheres for relatively long period of time, minimizing the manpower needed to resoak the structure. Because the quantity of water absorbed by the additive evaporates less quickly than that provided by pure water, use of this additive will also provide more water to prevent and/or extinguish fires. Using this water-additive mixture to coat a structure that is near a fire allows the additive to provide a protective coating to the structure. Thus, the fire will not spread as rapidly because it must overcome the effects of the significant quantity.of water present in the molecules of the additive that adhere to the structure. This additive can be added to the firefighting water is via eduction or batch addition to the source water. The nature and properties of the additive enable eduction through standard firefighting equipment. Brief Description of the Drawinas Figure 1 is an illustration of typical equipment used in the preferred embodiment of the method of the present invention using the water additive of the preferred embodiment of the present invention; and Figure 2 is a schematic representation of the use of the preferred embodiment of the present invention. Description of the Preferred Embodiment The present invention are methods involving the use of a water additive in fire prevention and fire extinguishing. In the preferred embodiment, the additive is a water-in-oil cross-linked polymer produced by inverse phase polymerization. As shown in Figure 1, the additive is educted into a fire hose 10 in a manner similar to that currently used to educt firefighting foams, such as AFFF (aqueous film-forming foam). A trailing hose 12 is placed in a bucket 14 of additive. The flow of water through the fire hose 10 creates a negative pressure at an eductor nozzle, schematically represented by numeral 16, which then draws the additive from the bucket 14 into the flow of water through the fire hose 10. The eductor nozzle 16 has an internal valve by which the flow of additive may be controlled. This additive may be used with existing standard firefighting equipment and does not require purchase of new equipment, as does the use of the solid, powdered additives that are traditionally available. Because the present additive is a flowable emulsion, there is no need to add a carrying or release agent to enable it to be educted or mixed, as is necessary with the traditional powdered additives, such as that represented by the US 4,978,460A, issued to von Blücher et al. As an alternate method, the additive may be batch added to the water tank 18 on a fire truck 20. Once-again, because the additive is emulsified, there is no need for the extensive agitation disclosed in the prior art or for addition of a separate carrying or release agent to avoid clumping, as is necessary with the solid additives that are presently used. Some mixing is still required in such a batch addition. The additive combines the properties of a superabsorbent polymer, in that it can absorb significant quantities of water in relation to its size and weight, and a thickener, in that the resulting water-additive mixture has a relatively high viscosity. In the non-mixed state, the additive is contained within the droplets of water dispersed in oil in a water/oil emulsion. With the help of an emulsifier, the water droplets are relatively evenly distributed throughout the emulsion. When the additive is introduced to a significant quantity of firefighting water, such as through eduction into a fire hose or batch addition into a water tank, the water droplets mix with the firefighting water and the tiny (generally <1 µm in size) polymer particles within the water droplets are now exposed to a large volume of water and absorb significant quantities of the water. The additive used according to the present invention is produced by inverse phase polymerization, as are thickeners. Thus, the resulting additive is an emulsion polymer in a liquid form, unlike traditional superabsorbent polymers which are in powdered, granular form. Production of the additive through inverse phase polymerization also results in a particle size that is always less than about 2 microns, and generally less than about one micrometer. The size of the particles in typical superabsorbent polymers sed in firefighting is almost always (99 %) greater than 20 micrometers. Swollen emulsion polymers also react differently in the presence of water than do typical superabsorbent polymer particles. Typical particles retain their individual particle integrity when swollen, and may tend to clump, whereas the swollen emulsion thickener particles form a homogeneous, highly viscous fluid. Because of the nature of the emulsion polymer, the resulting water-additive mixture has a short (less than about three seconds) swell time, relatively high viscosity, allowing the mixture to easily adhere to both vertical and horizontal surfaces, and sufficient fluidity to allow the additive to be easily educted through standard firefighting equipment. When the water-additive mixture is sprayed onto a vertical or horizontal surface, the mixture adheres to the surface, providing extended fire protection for structures located near a fire. As illustrated in Figure 2, when the mixture is sprayed onto a surface 22, millions of additive polymer particles containing water 24 are stacked on top of each other. This is similar to how AFFF and other foams are used, but the polymer particles 24 of the present invention are laden with water and the traditional foam bubbles are filled with air. This water fill dramatically enhances the thermal protection qualities of the present invention. When the fire approaches the surface, the outer polymer particles 24 that are closest to the fire absorb the heat until the point of water evaporation is reached. This protects the polymer particles 24 that are closer to the wall until the water of the outer polymer particles 24 evaporate. Then the next layer of polymer particles 24 absorb heat until the point of water evaporation is reached, shielding the remaining inner layers of molecules. This process continues until the water of the innermost layer of polymer particles 24 is evaporated. This process absorbs heat significantly more effectively than does the use of conventional foams that use air instead of water to absorb the heat. Water is able to absorb more heat than that absorbed by air bubbles. As an additional benefit, by the time that the fire has evaporated the water from the molecule layers down to the protected surface, the additive coating the surface above the point of fire penetration will slide down to partially re-coat and continue to protect the area penetrated by the fire. This also minimizes the manpower and material resources currently necessary to periodically resoak the surface. Obviously, at some point the fire will evaporate substantially all of the water from the additive if the fire continues to burn. But by retarding the advance of the fire and the damage done by the fire, and by using the additive to directly fight the fire, firefighters will be able to more effectively fight the slowed fire and the damage done by the fire will be significantly reduced from what the damage would be using conventional firefighting techniques and materials. This represents a substantial leap forward in firefighting technology. When water is sprayed directly onto a fire, much of the water never effectively fights the fire, because the superheated air above the fire evaporates the water before the water can reach the flames. When the present additive is used, the same principles of heat absorption discussed above allow more water to reach the fire. Because in the water-laden additive polymer particles the water is bound in the form of a gel in contrast to simple water molecules, the evaporation process is slowed. Thus, more water reaches the fire and the fire is doused with less water than when using simply water, or even when using conventional additives, such as fire fighting foams. Also, when simply applying water, a large proportion of the water that is applied directly to the fire and is not evaporated runs off or soaks into the ground and is thus wasted after its initial application. As an additional benefit, the water-additive mixture of the present invention also coats the ashes or the charred structure that was burning, instead of running off or soaking into the ground, and helps to prevent reflashing, because the waterladen molecules are able to absorb heat and the mixture, which is viscous, adheres to the surface and deprives the location of the oxygen needed for combustion, thus providing a smothering effect on the burned surface. Because of these properties of the additive, the wateradditive mixture is also suitable for use as an artificial fire break when fighting forest or brush fires. The mixture can be sprayed in advance of the fire and will coat the structure, such as bushes and trees, such that the fire will stop its advance when it reaches the treated area, allowing the firefighters to extinguish the flames without the fire advancing further. This causes significantly less damage than does the use of conventional means of fire breaks, such as using Bulldozers or controlled burning to clear an area for a fire break. The key to the success of this additive is the fact that it can absorb water in significant quantities relative to its own weight. These polymer particles contain 30 - 40 % water by weight before they are introduced to the firefighting water. Once the additive particles have been added to the firefighting water and absorb this water to near their capacity (which takes about 3 seconds), they will carry more than 90 % of the water (by weight) that is used to fight the fire. The polymer is preferably a cross-linked, water-swellable polymer in a water/oil emulsion that is produced by an inverse phase emulsion polymerization process. While inverse phase emulsion polymerization is known, such as disclosed in US 3,284,393A, US 4,021,399A and US 4,925,884A, it has not been known or suggested to utilize inverse phase emulsion polymerization reations to produce a water additive having characteristics suitable for use in preventing and extinguishing fires as in the present invention. In the inverse phase emulsion polymerization process according to the present invention, the aqueous solution of monomers is emulsified in an organic liquid such as mineral oils, petroleum spirit of boiling range 150° - 200° C and/or an oil of vegetable or animal origin and/or derivates thereof, for example rape oil-methylester. Particularly useful oils are paraffinic or isoparaffinic solvents. The organic liquid also contains at least one emulsifier in amounts ranging from 0,5 % to about 10 % by weight which serves to stabilize the W/0-monomer-emulsion during polymerisation. The emulsifier can be selected from the group of surfactants that include sorbitanesters, phathalic esters, fatty acid glycerides as well as ethoxylated derivates thereof, linear or branched ester-ether blockcopolymers such as disclosed in EP 0 000 424 A1 and/or prefered emulsifying agent of the typ disclosed in US 4,786,681A. A particularly suitable emulsifying agent is Hypermer 2296 (from ICI, London, England). The organic liquid comprises from about 20 to about 80 % by weight of the total emulsion composition. The water-swellable, cross-linked polymer may be prepared from hydrophilic monomers for example from olefinically unsaturated carboxylic acid and/or carboxylic acid anhydride monomers that include acrylic acid, methacrylic acid, itaconic acid, crotonic acid, glutaconic acid maleic acid and maleic acid anhydride and/or a watersoluble salt thereof, olefinically unsaturated sulfonic acid monomers include aliphatic or aromatic vinyl sulfonic acids such as vinylsulfonic acid, allylsulfonic acid, styrenesulfonic acid, acrylic- and methacrylicsulfonic acids such as sulfoethylacrylate, sulfoethylmethacrylate, sulfopropylacrylate, sulfopropyl-methacrylate, 2-hydroxy-3-methacryloxypropyl sulfonic acid and 2-acrylamide-2-methyl-propane sulfonic acid (AMPS) and/or a water-soluble salt thereof. The prefered water-soluble salts of acid monomers are Na-, K-,Li-salts or a mixture of them. Some other water-soluble or water-dispersible monomers can also be used, for example water-soluble or water dispersible derivates of acrylic or methacrylic acids such as acrylamide, methacrylamide, n-alkyl substituted acrylamides and/or 2-hydroxyethylacrylate, 2-hydroxyethylmethacrylate, hydroxypropylacrylate, hydroxypropyl-methacrylate, C 1 - C 4 - alkyl(meth)acrylate and vinylacetat. The monomers can be used alone or in mixture with at least one other. The monomer mixture contains till 1 % by weight of at least a difunctional cross-linking agent such as methylenbisacrylamide, allyl(meth)acrylate, diallylphthalate, polyethylene glycol di(meth)acrylate, tetraethyleneglycol di(meth)acrylate, triethyleneglycol di(meth)acrylate, diethylene glycol di(meth)acrylate, glycerol di(meth)acrylate, hydroxypropyl (meth)acrylate, trimethylolpropane tri(meth)acrylate and triallyl methyl ammonium chloride. The copolymerisation reaction is generally initiated using free radical polymerization techniques known to those skilled in the art. For example azocompounds, peroxid polymerization initiators and redox catalysts can be used alone or in combination with one another in amounts ranging from 0,001 to 5 % by weight relating to the amount of monomers employed: After polymerization additionally water may be distilled off under reduced pressure along with boiling solvent to achieve products with a high concentration of solids. Alternatively the emulsion polymer can also be vacuum distilled to remove the solvents or spray dried. The dried product so obtained is a white granular, pourable powder which is swellable in water and can also be used as a water additive of the invention. Preferably the polymer emulsion may be directly inverted by a sufficient amount of a suitable breaker surfactant (invertor) to an oil-in-water emulsion for use as water additive in water or aqueous solution. Preferably, the breaker surfactant (invertor) is added to the monomer emulsion or to the polymer emulsion in amount from about 0,5 to about 10 % by weight based upon the total emulsion. Typical breaker surfactants (invertors) are those having a high HLB number greater than 10 such as ethoxylated octyl and nonylphenols, polyethylen oxide esters of fatty acids, polyethoxylated alcohols, dioctyl esters of sodium sulfosuccinate and others. Suitable combinations of breakers surfactants can also be employed. Generally the W/O-emulsion has a polymer content in the range from about 10 to about 70 % by weight, preferably about 20 to about 50 % by weight and most prefered about 25 to about 35 % by weight. The degree of cross-linking of the polymer substantially affects the viscosity and adherence properties of the resultant polymer. A prefered suitable cross-linking chemical for this application is triallyl methyl ammonium chloride. Modification of the use of this chemical results in a different viscosity when the water additive is mixed with water. A viscosity of significantly greater than 100 mPa·s, and even in the range from 500 mPa·s to 50,000 mPa·s is easily obtainable and beneficially obtained with the additive of the present invention. This is in contrast with the state of the art as represented by US 5,190,110A, issued to von Blücher et al., which teaches that viscosities above 100 mPa·s are undesirable and unworkable in fighting fires. The higher viscosities supported by the present invention allow the additive to have better adherence to vertical surfaces, and still are sufficiently fluid such that the additive can be successfully educted through standard firefighting equipment. The water swellable polymer can also be used in combination with a water-soluble emulsion polymer. Because the degree of hardness of the water, in other words the amount of cations in the water, affects the degree of swelling of the additive particles, a component is also introduced to counteract this effect. A suitable chemical for this countereffect in this application is AMPS or its derivatives. It will be obvious to one skilled in the art that the amount of AMPS included in the additive may be varied depending on the hardness of the water in the particular region of use. Also, the additive is effective without inclusion of a chemical to counteract the water hardness, particularly in those regions of the country that do not experience hard water. Another factor that contributes greatly to the swell time is the size of the particles. The particle size of the present invention is generally less than one micron and 100% of the particles are less than about 2 micrometers. This is a significant improvement over typical superabsorbent polymer particles used in fire protection and prevention, the size of which is generally greater than 100 micrometers, and not disclosed to be less than 20 micrometers. The smaller particles of the present invention allow for a shorter swell time which, in turn, allows for the particles to complete the swell during the time the water-additive mixture is in the fire hose after the point of eduction. The additive of the present invention preferably has a swell time of no more than about three seconds when educted through standard firefighting equipment, whereas the swell time of the particles in the current state of the art have, at best, a swell time of about 10 seconds (see, e.g., von Blücher et al. '460), and often disclosed in terms of minutes or hours (see,.e.g., US 3,247,171A, issued to Walker et al.), before the traditional firefighting additives have absorbed sufficient water to be suitable for use. These longer swell times are inadequate for use of the traditional additives in an eduction system without significant advance preparation and/or use of special equipment. One particular aspect of the invention is the determination appriopriate invertor(s) and ratios in which they are added to the polymer emulsion as thereby the swell time may be controlled, for example such that the swell time of the particles is ≤ 3 seconds. The two invertors that were determined to work optimally are nonyl phenol, 4 moles EO, and nonyl phenol, 6 moles EO in a 1:4.3 ratio by weight. Because of the short swell time and the water/oil emulsion state of the additive of the present invention, versus the dry powder state of the current art particles, the additive of the present invention is superbly situated to be used in a standard eduction system with a fire hose and a water source, such as a tanker truck or a fire hydrant. This eliminates the need for special equipment to practice the invention. It will be obvious to one with skill in the art that the present invention is also suitable for use by directly adding the additive to the tank in a tanker truck. To this end, only five gallons of additive is necessary to treat the standard 500 gallon (1894 liter) tank on a fire tanker truck. This is less than 50 pounds (23 kg) per 500 gallons (1894 liter). This is a significant improvement over the state of the art, as illustrated by the von Blücher et al. '460 patent, wherein 200 grams of additive are required for every liter of water, which is equivalent to about 835 pounds (378 kg) for a typical 500 gallon (1894 liter) tank. Thus, the present invention results in significantly less bulky material being required to be present at the scene to aid in combating a fire. Several tests of the additive have been conducted to evaluate the firefighting and fire protection properties thereof. The water additive used in test example 1 is a polymer emulsion of a terpolymer obtained from Na-acrylate, Na-AMPS and acrylamide (mol-ratio 80/2,5/17,5), solid content 29 % by weight. TEST EXAMPLE 1 A 4 feet by 8 feet (122 cm by 244 cm) sheet of 3/8 inch (0.95 cm) plywood was coated to a thickness of 1/8 to 1/4 inch (0.32 to 0.64 cm) with a 1.5 % solution of the water-additive mixture. Following this application, the plywood was subjected to an open flame generated by a propane gas jet and the time to burn through was measured and compared with the time to burn through of an identical sheet of plywood which was not treated. The burn-through time for the treated plywood was 11 minutes, 7 seconds. The burn-through time f or the untreated plywood was 3 minutes, 0 seconds. TEST EXAMPLE 2 A 4 feet by 8 feet (122 cm by 244 cm) sheet of 3/8 inch (0.95 cm) plywood was coated in the same manner as in test example 1 with the water-additive mixture and subjected to a temperature of 2800 degrees. An identical untreated sheet of plywood was exposed to the same conditions. The untreated sheet was fully engulfed in flames in 45 seconds, and the wood was charred so badly that the surface was burned off, leaving it thinner. The treated sheet, with a coating of 2 % solution of the additive, did not burn at all, except for a small area where the heat moved the coating. Even the supports behind the wall burned because of the heat, but not the plywood sheet. Other tests have also been conducted that demonstrate the exceptional fire protection and firefighting properties of the present invention. In application, the additive may be provided in five gallon (19 liter) buckets for use with a standard eduction system. The concentration of additive for the eduction is preferably between 0.01 % and 10 % (volume to volume), but concentrations of up to about 50 % are acceptable. Once the concentration is significantly above 50 %, the viscosity of the water-additive mixture becomes unwieldy. Likewise, for use in direct mixing into a tank, the additive is batch mixed in a concentration of preferably between about 0.01 % and 10 % (volume to volume), but concentrations of up to about 50% are acceptable. It is noted that additive concentrations of from about 1.0 % to about 2.0 % (volume to volume) provide suitable characteristics for firefighting, and thus greater concentrations are generally unnecessary. The use of lower concentrations also improves cost effectiveness.

Claims: A method for adding an additive to water used in fire prevention and in fire extinguishing, characterized by mixing the additive with the water while the water is pumped from a source of water to an outlet, and wherein the additive is a water-in-oil emulsion in which particles of cross-linked, water-swellable polymer are dispersed which emulsion is produced by an inverse phase emulsion polymerization process. The method according to claim 1, characterized in that the additive is mixed with the water in a concentration of from 0.01 % by volume to 50 % by volume. The method according to claim 1, characterized in that the additive is mixed with the water in a concentration of from 0.01 % by volume to 10 % by volume. The method according to claim 1, characterized in that the additive is mixed with the water in a concentration of from 1 % by volume to 2 % by volume. The method according to one of the claims 1 to 4, characterized in that the mixing of the additive with the water results in a water-additive mixture with a viscosity above 100 mPa s. The method according to one of the claims 1 to 4, characterized in that the mixing of the additive with the water results in a water-additive mixture with a viscosity of from 500 mPa s to 50,000 mPa s. A method for applying an additive to a surface to combat fires, comprising adding the additive to water in an amount sufficient to increase the viscosity of the resulting water-additive mixture above 100 mPa s, wherein the additive is a water-in-oil emulsion in which particles of cross-linked, water-swellable polymer are dispersed and wherein the additive is made by an inverse phase emulsion polymerization reaction. The method of claim 7, wherein the size of the polymer particles is less than two micrometers. The method of claims 7 or 8, further comprising the step of educting the additive into the water through standard firefighting eduction equipment. The method of one of the claims 7 to 9, further comprising the step of batch-adding the additive to the water prior to use of the water in firefighting. The method of one of the claims 7 to 10, wherein the additive is added to the water in a concentration of from 0.01 % by volume to 50 % by volume. The method of one of the claims 7 to 10, wherein the additive is added to the water in a concentration of from 0.01 % by volume to 10 % by volume. The method of one of the claims 7 to 10, wherein the additive is added to the water in a concentration of from 1 % by volume to 2 % by volume. The method of one of the claims 7 to 13, wherein the addition of the additive to the water results in a water-additive mixture with a viscosity of from 500 mPa s to 50,000 mPa s. The method of claim 7, wherein the polymer is comprised of at least one monomer selected from the group consisting of hydrophilic monomers. The method of claim 15, further characterized in that the polymer is comprised of acrylic acid and/or acrylic acid derivatives. The method of claim 16, further characterized in that the polymer is comprised of at least a salt of acrylic acid and acrylamide. The method of claim 16, further characterized in that the polymer is a terpolymer of a salt of acrylic acid, acrylamide, and a salt of 2-acrylamido-2-methylpropanesulfonic acid. The method of one of the claims 7 or 15 to 18, further characterized in that the swell time of the polymer particles is no more than three seconds.

Inventors: AGNE ROBERT ANDREW, HICKS ROBERT DAVID, HSU WHEI-NEEN, MILLS JANE ELISABET, AGNE, ROBERT ANDREW, HICKS, ROBERT DAVID, HSU, WHEI-NEEN, MILLS, JANE ELISABET
Applicants: STOCKHAUSEN INC, STOCKHAUSEN, INC.
Application year: 1996
Main classification: A62D1
IPC codes: C08L33, B01J13, A62D1, C08L101, C09K21, B01F17