US3833062A

US3833062A - System and method for extinguishing fire

Info

Publication number: US3833062A
Application number: US00263249A
Authority: US
Inventors: W Livingston
Original assignee: Factory Mutual Research Corp
Current assignee: Factory Mutual Research Corp
Priority date: 1972-06-15
Filing date: 1972-06-15
Publication date: 1974-09-03
Anticipated expiration: 1991-09-03

Abstract

A system and method for extinguishing fires is provided which includes applying an aqueous solution of a gel-forming material to structures in an area to be protected and separately applying an aqueous solution of a gel-inducing material to the same structures so that the solutions will mix and form a blanket of gas impervious aqueous gel which flowingly envelopes the structures and tends to smother any fire therein. The preferred gel-forming material is polyvinyl alcohol and the preferred gelinducing material is borax.

Description

1 1 Sept. 3', 1974 United States Patent [1 1 Livingston 169/15 Degginger......................... 169/14 X n a n a E U O D 00 2 677 WWW WWW 69 726 78 2 1 6 087 456 3 3 3 n O r a h S m w a F m D .w. m L m L. m MM m D H mm w U MG m mm m a t. SE .m M v 5 U U Primary Examiner-M, Henson Wood, Jr. Assistant Examiner--John J. Love Mass.

Attorney, Agent, or Firm-Lane, Aitken, Dunner & Ziems [73] Assignee: Factory Mutual Research Corporation, Norwood, Mass.

June 15, 1972 [22] Filed:

[57] ABSTRACT A system and method for extinguishing fires is pro- 21 Appl. No.: 263,249

videdwhich includes applying an aqueous solution of a gel-forming material to structures in an area to be protected and separately applying an aqueous solution al to the same structures so [52] US. 169/15, 169/16 [51] Int. A62c 35/00 [58] Field of Search............. 169/1 A, 5, 13, 14, 15,

of a gel-inducing materi e 3 m o a 0. eb ke am e VJ me mm w mo fl nh .m h 'mw 14. 5 WW n mm ma mS SU em m MD. mm

References Cited UNITED STATES PATENTS structures and tends to smother any fire therein. The referred gel-forming material is polyvinyl alcohol and P the preferred gel-inducing material is borax.

26 Claims, 4 Drawing Figures I e n r. e w

1,421,433 Epps 1,597,516 8/1926 Epps 2,580,011 12/1951 Freeman. 3,198,258 8/1965 SYSTEM AND METHOD FOR EXTINGUISHING FIRE BACKGROUND OF THE INVENTION This invention relates to a fire control and extinguishing system and method. More particularly, the invention is directed to a system and method in which a substantially gas impervious blanket of aqueous gel material is formed over objects in an area on fire and thereby create a relatively closed environment in which the fire will, in effect, be smothered and extinguished.

In relatively recent years a number of developments have occurred in the fire control art which involve the use of extinguishant other than water. For example, the use of foam blankets in fighting high energy fires, particularly fuel fires, is well known. In most cases foam blankets are applied from mobile units although the use of foam in connection with fixed extinguishing systems is also known. While the use of foam has proved to be effective in areas where direct application to a fire is possible, it has limited usefulness in fighting fires in materials having large vertical surfaces, particularly in enclosed areas protected by fixed extinguishing systems. In such cases, the system operates automatically and does not have the capabilities of applying the foam directly to the core" of the materials on fire. Thus, in a warehouse fire, for example, involving stacks or pallets of combustible materials, foam generated from a fixed system will perhaps coat the top portions of the materials and may even cover parts of the exposed vertical surfaces of the stacks. However, the foam will have no direct or indirect effect on the fire raging in the interior portions of the pallets and will thus often be ineffective in preventing destruction of the pallets. In addition, the fire may accelerate to the point where even the foam itself dissipates leaving the previously coated top and outside vertical portions of the pallets exposed to the flames.

Of course, foam is not the only new development in fire control. Ablative water gels have been shown to be particularly effective in fixed and mobile fire extinguishing systems. For example, in US. Pat. No. 3.605.900 entitled Method of Controlling Fire" issued to William L. Livingston and Russell W. Pierce and assigned to the assignee of the present invention, a method of fire protection is disclosed in which a gelling agent in the form of a water-swellable polymer is injected into a flowing stream of water supplying the sprinkler heads of a fixed extinguishing system upon actuation thereof to put out a fire in the enclosure protected by the system. By so introducing the gel into the flowing water stream. an ablative gel extinguish-ant is formed and is discharged towards the fire. Since the gel enjoys a relatively high thermal absorption characteristic and a relatively high viscosity, a relatively low quantity of ablative extinguishant is required to put out the fire, thereby enabling system designs with lower flow capacity, not to mention a significant reduction in water damage to the place protected. Also the gel tends to cling to the surfaces on which it is sprayed to promote the smothering effect discussed above. While this method has proved to be extremely effective in fighting high energy fires, it does not fon'n a blanket" over vertical surfaces and thereby produce a relatively closed environment in which a fire will be smothered.

SUMMARY OF INVENTION Accordingly, it is an object of the invention to provide a system and method in which the combustible materials are covered with a blanket of aqueous gel to assist in smothering, and therefore extinguishing any fire within the materials.

Another object of the invention is the provision of a low cost system and method for extinguishing a high energy fire by covering combustible materials in the area of the fire with a fire extinguishing blanket comprising a substantially gas impervious aqueous gel.

It is a further object of this invention to provide a system and method for extinguishing fire in materials hav ing a relatively large vertical surface area by forming an aqueous gel on the materials so that it flows down the vertical surfaces thereof forming an ablative, substantially gas impervious blanket which is effective in smothering the fire.

The system which achieves these and other objects of the present invention features a plurality of discharge heads disposed in an elevated position in a space to be protected from fire, delivery means for separately de- BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a perspective view of a building equipped with an automatic fixed fire protection system of the present invention;

FIG. 2 is an enlarged sectional view taken along the line 22 of FIG. I; and

FIGS. 3 and 4 are views similar to FIG. 1, but depicting alternative embodiments of the system of the pres ent invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. I of the drawings, a building I0 is shown in phantom lines which is equipped with an automatic fixed fire protection system embodying features of the present invention. In particular, the system comprises a buried feed main 12 connected to a municipal water supply line I4 for delivering water to a piping system including a pair of

parallel injector lines

16 and 18, respectively, connected to a pair of

risers

20 and 22. The feed main 12 extends beyond the

lines

16 and 18 and can be connected to injector lines of other buildings or, in the case of a large building, to other injector lines of the same building. 7

A pair of

injecting systems

24 and 25 are respectively connected to the lines 16 and I8 and are adapted to inject additives from

storage tanks

26 and 27 into the

lines

16 and 18, respectively, as will be described in detail later;

The

risers

20 and 22 are connected to a pair of

crossmains

28 and 30, respectively, which run for the length of the building 10 adjacent two opposed walls thereof as shown. A plurality of spaced branch lines 32-register with the crossmain 28, while a plurality of spaced branch lines 34 register with the crossmain 30, the

branch lines

32 and 34 being alternately disposed at equal distances apart, as shown. The

crossmains

28 and 30, as well as the

branch lines

32 and 34, may all be suspended from the ceiling of the building in a conventional manner.

A plurality of spaced direct discharge nozzles, shown in general by the reference numeral 36, depend from each of the

branch lines

32 and 34, with the locations of the nozzles along each particular branch line being staggered with respect to the nozzles of its adjacent branch lines, as shown.

The

injector systems

24 and 25 can be identical to the system disclosed in applicant's US? Pat. No. 3,642,072, issued Feb. 15, 1972, and assigned to the same assignee as the present application, with the disclosure of the patent being hereby incorporated by reference. In general, the system includes a hydraulic motor driven by the water tapped at line pressure from the water conduits supplying the system which, in the system of the present invention, would be the

lines

16 and 18. The motor drives an injection pump by which stored additive is introduced into the flow lines in direct proportion to the water flow rate through the lines, with the increase of injection with increasing flow rates being terminated after a predetermined flow rate is attained. The system is controlled by a servo mechanism driven in part by a flow sensor in the water line to in sure injection rates corresponding to the water flow. Since the specific details of the injector system are dis closed in the above patent, it is not shown, nor will be further described, in any detail in the present application.

According to the present invention the additive stored in the tank 26 and injected into the line 16 by the injector system 24 is a gel-forming material preferably in the form of water-soluble polyvinyl alcohol, while the additive stored in the tank 27 and injected into the line I8 by the injector system 26 is a gelinducing material, such as borax. The specific details of these materials will be discussed later.

The specific arrangement of the nozzles 36 are shown in FIG. 2. In particular three nozzles 36, one from a branch line 32 and two from the adjacent branch lines 34, are shown in an actuated. open condition in which they discharge extinguishant towards a supply of materials 40 stored in the building 10.

The nozzles 36 can be identical to the nozzle disclosed and described in copending US. Pat. applica tion Ser. No. 160.7l5, filed July 8, 1971, and assigned to the same assignee as the present invention. the disclosure of the application being hereby incorporated by reference. The nozzle is formed by a body member having an inlet for connection to the branch lines and an outlet for discharging extinguishant. A closure member normally closes the outlet to prevent the discharge of extinguishant therefrom. The nozzle is opened in response to the existence of both a predetermined fire condition, such as a predetermined temperature in the space to be protected, and a predetemiined condition .of the system, such as a predetermined extinguishant pressure in the nozzle. In the event the nozzle is not opened despite the occurrence of the above-mentioned predetermined temperature, it may later be opened in response to the existence of both a second predetermined ftre condition, preferably in the form of an additional predetermined temperature above the abovementioned predetermined temperature, and a second predetermined condition of the system, preferably in the form of an additional pressure of the fluid in the system lower than the above-mentioned fluid pressure. The nozzle can also be opened in response to the existence of a third temperature in excess of both of the abovementioned temperatures in the event it does not open under any of the above-mentioned conditions.

Since this nozzle is disclosed in complete detail in the above-mentioned application, it is not shown, nor will be described in any further detail in the present application.

According to a preferred embodiment, the

branch lines

32 and 34, as well as the nozzles 36 on each branch line are spaced 10 feet apart. Also, as shown in FIG. 2, the spray pattern from each nozzle forms an angle of approximately 125. As a result, the gelforming solution from the nozzles 36 on the branch lines 32 mixes with the gel-inducing catalyst solution from the nozzles on the branch lines 34 in the general areas shown by the letter X in FIG. 2 of the drawings.

It should be understood that the sizes of the

conduits

28, 32 and 34, as well as the nozzles 36 have been greatly exaggerated in FIG. 2 for the convenience of presentation and that, in actual practice, these components will be much smaller in size relative to the dimensions of the building 10 and the materials 40.

The aqueous gel utilized in this invention must be capable of substantially maintaining its integrity on vertical surfaces so that a relatively closed environment will be created in which a fire cannot be sustained. The preferred material for forming such an aqueous gel is water-soluble polyvinyl alcohol. When used in the context of this invention, the term polyvinyl alcohol should be taken as referring not only to that substance as such but also including partially hydrolyzed polyvinyl acetate. Polyvinyl alcohol and partially hydrolyzed polyvinyl acetate may both be prepared by hydrolysis or alcoholysis of polyvinyl acetate using alkaline or acid catalysts, but conversion of acetate to hydroxyl groups is essentially complete in the case of polyvinyl alcohol. Commercial samples of partially hydrolyzed polyvinyl acetate usually correspond to -80 percent hydrolysis. Such samples and those of polyvinyl alcohol are both soluble in water, but the process of dissolution and the variation of solubility with temperature differ in the two cases. Polyvinyl alcohol is a light, white, powdery solid when pure. It is soluble in water to viscous proportions but only when the water is heated to a temperature above about C. 158 F.). Alternatively, it can be rendered soluble in water at room temperature by completely glassifying it with plasticizing agents such as high molecular weight esters, dextrin and glycerol. However, since in most applications envisioned by this invention, polyvinyl alcohol will be dissolved in cold water, partially hydrolyzed polyvinyl acetate, or in other words, polyvinyl alcohol containing 20-40 percent acetate groups, is preferred. Such a substance dissolves readily in cold water and, as described hereinafter, reacts favorably with a catalyzing agent to produce the intended gel. The polyvinyl alcohol may be stored in the tank 26 as an aqueous solution or a watermiscible organic solvent solution for subsequent injection into the line 16. For convenience and economic reasons the aqueous solution is preferred. The concentration of polyvinyl alcohol in the stored solution is not critical but either the concentration or injection rate must be adjusted so that when mixed with the water in the line 16, it is present in a concentration of about 24 percent by weight. Thus, the aqueous solution discharged from the nozzles 36 on the branch lines 32 will comprise about 2-4 percent polyvinyl alcohol.

The catalyzing agent employed in this invention may be any water-soluble substance capable of inducing the formation of an aqueous gel when mixed with the gelforming material, particularly polyvinyl alcohol, described above. The preferred substance in this regard is borax, i.e., sodium tetraborate lO-hydrate. This substance is a mineral obtained directly from certain areas of the earth or it may also be prepared from kemite (Na B O '4H O). It is readily soluble in water and may be stored in the tank 27 as an aqueous solution. The amount of borax injected into the water in the line 18 is not critical so long as it is sufficient to form the intended gel. Thus, even the discharge of a saturated aqueous borax solution from nozzles 34 will cause the gel to form. However, in the usual case the concentra tion and/or injection rate of the stored borax solution will be such as to effect a discharge of a l2 percent by weight aqueous borax solution from nozzles 34.

The mixing of these two solutions will, for the most part, take place on the surfaces of structures to which they have been applied. However, some preliminary mixing may take place in areas above the structures. These areas are designated in FIG. 2 by the letter X. As a result, a blanket of macrogel is formed on the surfaces of the stored materials 40 which, for the purposes of this application, will be defined as an infinite network structure of high molecular polymer chains which extend to its limiting boundaries. Two such blankets are shown by the reference numerals 42 in FIG. 2. The macrogel thus formed is of a dilatant nature, that is, the viscosity thereof increases with corresponding increases in applied molecular shear stress. In this respect. the macrogel behaves very much like silly putty," a well-known composition sold commercially as a play-toy for children. Thus, the macrogel blankets 42 will exhibit a plastic, or pseudoplastic flow and fall by gravity until they cover the materials 40 in the manner shown in FIG. 2. Such blankets are gas impervious and when exposed to thermal energy will form steam or water vapor. Also, since the gel does not have internal convection, it will shield the surrounding areas from thermal energy generated by the fire. Since the blankets are gas impervious and substantially envelop the materials 40, they will tend to cause oxygen starvation of the fire. Furthermore, the fire itself will generate gases which, in the absence of oxygen, will tend to smother the fire. As a result, the blankets 42 not only extinguish the fire on the exposed surfaces of the materials, but they also smother any fire in the interior portions or core of the materials.

After the fire has been extinguished, clean-up of the area may be easily accomplished since handling causes the macrogel to increase in viscosity to a point where it behaves like a rigid gel. Thus, it can be shoveled or otherwise picked up very easily.

Since the embodiments of FIGS. 3 and 4 are similar to that of FIGS. 1 and 2, identical or substantially identical structure will be given the same reference numbers. In the embodiment of FIG. 3, the

risers

20 and 22, and their

corresponding crossmains

28 and 30, are disposed towards the center of the building and extend slightly abovetheir

corresponding branch lines

32 and 34, with the

injector lines

16 and 18, the

injectors

24 and 25, and the

storage tanks

26 and 27 being otherwise identical to that of the embodiment of FIGS. 1 and 2.-

A plurality of vertically extending connecting conduits 29 connect the crossmain 28 to its respective branch lines 32, and a plurality of vertically extending connecting conduits 31 connect the crossmain 30 to the branch lines 34.

A plurality of crosslines 35 connect adjacent pairs of

branch lines

32 and 34 at spaced intervals and are adapted to receive the heads 36.

The operation of the system of the embodiment of FIG. 3 is similar to that of FIG. I in that occurrence of a tire condition in the building 10 causes actuation of one or more of the heads 36, resulting in water flowing from the line 14 through the main l2 and into the injector lines 16 and I8. Polyvinyl alcohol from the tank 26 will be injected into the line 16 by the injector 24, while borax from the tank 27 will be injected into the line 18 v by the injector 25. The resulting polyvinyl alcohol solution and borax solution then flows through the

risers

20 and 22, the crossmains 28 and and the crossline, or crosslines, corresponding to the attached head, or heads, 36. The solutions will mix in each head 36 and form a blanket of macrogel which will discharge from the head toward the materials to flowingly envelop same as discussed in connection with the previous embodiment.

In the embodiment of FIG. 4, a T-shaped coupling 19 is provided which connects each of the

injector lines

16 and 18 to a single vertical riser 21. Otherwise the

injector lines

16 and 18, their corresponding

injectors

24 and 25, and the

storage tanks

26 and 27 are identical to those described in the previous embodiments.

The riser 21 is connected to a crossmain 29 which in turn is connected to a plurality of laterally extending branch lines 31 which receive the heads 36.

A control device 38 is operatively connected between the

injectors

24 and 25 to insure that they will operate to selectively, intermittently inject polyvinyl alcohol from the storage tank 26 and borax from the storage tank 27 into their

respective lines

16 and 18 according to a predetermined cycle, in response to water flow through the lines as a result of one or more heads 36 being actuated. Since the control device 38 can be in any of a number of conventional forms, it is shown only schematically and will not be described in any further detail.

The polyvinyl alcohol and borax solution, as well as the pure water, will flow from the

lines

16 and 18 into the riser 21 and crossmain 29 for distribution to the actuated heads 36 via their respective branch lines 31.

Preferably the above-mentioned injection cycle is such that polyvinyl alcohol will be injected into the line 16 for a predetermined period such as 10 seconds, followed by a one second delay in which pure water flows into the riser 21 from one or both of the

lines

16 and 18, followed by a 10 second injection of borax into the line 18, followed by another one second delay in which pure water flows into the riser 21, before the cycle is repeated.

In this manner each head will receive an intermittent injection of polyvinyl alcohol followed by an injection of borax, and the two solutions will be discharged on top of each other near or at the materials 40, whereby they will mix to form the blanket as discussed in connection with the previous embodiments, which flow ingly envelops the materials.

Although the disposition of the heads 36 in the embodiments of FIGS. 3 and 4 is depicted as being similar to that of the embodiment of FIGS. 1 and 2, it can be appreciated that the former disposition can be varied somewhat as long as it is insured that all the materials stored in the building will be enveloped by the blankets formed.

The above embodiments are to be considered in all respects as illustrative and not restrictive since the invention may be embodied in other specific forms without departing from its spirit or essential characterisitcs. Therefore, the scope of the invention is indicated by the claims rather than by the foregoing description, and all changes which come within the meaning and range of the equivalents of the claims are intended to be embraced therein.

I claim:

I. A fire extinguishing system comprising a plurality of normally closed discharge heads, conduit means supporting said heads in an elevated position in a space to be protected from fire, said conduit means connecting said heads to a source of water and comprising a first group of spaced parallel branch conduits for receiving one group of heads and a second group of spaced parallel branch conduits for receiving another group of heads, means associated with each head for opening said head in response to a predetermined fire condition in its vicinity to permit said water to flow through said conduit means for discharge from said heads, delivery means responsive to said flow for separately delivering an aqueous gel-forming substance to said first group of branch conduits and an aqueous gel-inducing substance to said second group of branch conduits, said gelforming substance and said gel-inducing substance mixing with said water to form a solution of gel-forming substance and a solution of gel-inducing substance which are delivered to said one group of heads and said other group of heads, respectively, said first and second groups of branch conduits extending in an alternating relationship along said space and the position of the heads on each branch conduit being staggered relative to the position of the heads on its adjacent conduits to mix said solutions upon their discharge from said heads to form a fire extinguishing blanket of an aqueous gel material for goods stored in said space.

2. The system of claim 1 wherein said means for opening said heads is adapted to open said heads in a manner to permit each head in said one group to discharge said aqueous gel-forming substance at the same time a corresponding head in said other group discharges said aqueous gel-inducing substance.

3. The system of claim 2 wherein said heads are adapted to discharge said substances in a divergent spray pattern, with the spray pattern of each head in said one group of heads adapted to overlap the spray pattern of a corresponding head in said other group of heads so that said substances can mix at a predetermined vertical distance from said heads to form said blanket.

4. The system of claim 3 further comprising means for separately storing said gel-forming substance and said gel-inducing substance, said delivery means further including means for separately releasing said gelforrning and gel-inducing substances from said storage means to said first group of branch conduits and to said second group of branch conduits, respectively.

5. The system of claim 4 wherein said conduit means further comprises a first conduit connecting said source of water to said first group of branch conduits and a second conduit for connecting said source of water to said second group of branch conduits, said releasing means further comprising means for injecting said gelforming substance and said gel-inducing substance into water flowing in said first and second conduits, respectively.

6. The system of claim 1 wherein said blanket flowingly envelopes said goods and substantially covers same.

7. The system of claim 1 wherein said gel-forming substance is polyvinyl alcohol and said gel-inducing substance is borax.

8. A fire extinguishing system comprising a first group of spaced parallel conduits and a second group of spaced parallel conduits extending in an alternating relationship in an elevated position in a space to be protected from fire, means connecting said conduits to a source of water, a plurality of normally closed discharge heads positioned substantially intermediate two adjacent branch conduits and connected thereto, means associated with each head for opening said head in response to a predetermined fire condition in its vicinity to permit said water to flow through said conduit means to said heads, delivery means responsive to said flow for separately delivering an aqueous gel-forming substance to said first group of conduits and an aqueous gel-inducing substance to said second group of conduits for mixture with said water to form a solution of gel-forming substance and a solution of gel-inducing substance, respectively, for delivery to each of said heads, said heads being constructed and arranged to mix said solutions and discharge same in the form of a fire extinguishing blanket of an aqueous gel material towards goods stored in said space.

9. The system of claim 8 further comprising means for separately storing said gel-forming substance and said gel-inducing substance, said delivery means further including means for separately releasing said gelforming and gel-inducing substances from said storage means to said first group of spaced parallel conduits and said second group of spaced parallel conduits, respectively.

10. The system of claim 9 wherein said connecting means comprises a first and second conduit respectively connecting said first and said group of conduits to said source of water, said releasing means further comprising means for injecting additives into water flowing in said first and second conduits to form said gel-forming substance and gel-inducing substance, respectively.

11. The system of claim 8 wherein said blanket flowingly envelopes said goods and substantially covers same.

12. The system of claim 8 wherein said gel-forming substance is polyvinyl alcohol and said gel-inducing substance is borax.

13. A fire extinguishing system comprising a plurality of normally closed discharge heads disposed in an elevated position in a space to be protected from fire, conduit means connecting said heads to a source of water, means associated with each head for opening said head in response to a predetermined fire condition in its vicinity to permit said water to flow through said conduit means to said heads, delivery means responsive to said flow for selectively and intermittently delivering an aqueous gel-forming substance and an aqueous gelinducing substance to said conduit means for mixture with said water to fomi a solution of gel-forming substance and a solution of gel-inducing substance, respectively, for selective intermittent discharge from each of said heads to form a fire extinguishing blanket of an aqueous gel material over goods stored in said space.

14. The system of claim 12 wherein said conduit means comprises a riser connected to said source of water, a plurality of branch conduits connected to said heads, and a cross-main conduit connecting said riser to said branch conduits.

15. The system of claim 12 further comprising separate storage means for said gel-forming and gelinducing substance, said delivery means being adapted to selectively and intermittently release said gelforming and said gel-inducing substances from said separate sotrage means into said water flowing through said conduit means.

16. The system of claim 12 wherein said blanket fiowingly envelopes said goods and substantially covers same.

17. The system of claim 12 wherein said gel-forming substance is polyvinyl alcohol and said gel-inducing substance is borax;

18. A method of fire protection comprising the steps of disposing a first group of conduits and a second group of conduits in an alternating relationship in an elevated position in a space to be protected from fire, connecting a first group of normally closed discharge heads to said first group of conduits, connecting a second group of normally closed discharge heads to said second group of conduits with the position of the heads on each branch conduit being staggered relative to the position of the heads on its adjacent conduits, connecting said conduits to a source of water, selectively opening each head in response to a predetermined fire condition in its vicinity to permit said water to flow through said conduits for discharge from said heads, separately delivering an aqueous gel-forming substance to said first group of conduits and an aqueous gel-inducing substance to said second group of conduits in response to said flow, said gel-forming substance and said gelinducing substance mixing with said water to form a solution of gel-forming substance in said first group of conduits and a solution of gel-inducing substance in said second group of conduits. which flows to and is discharged from said first group of heads and said second group of heads, respectively, said solutions mixing upon their discharge from said heads to form a fire extinguishing blanket of an aqueous gel material for goods stored in said space.

19. The method of claim 18 wherein said heads are opened in a manner to permit each head in said one group to discharge said aqueous gel-forming substance at the same time a corresponding head in said other group discharges said aqueous gel-inducing substance.

20. The method of claim 19 wherein said heads are adapted to discharge said substances in a divergent spray pattern, with the spray pattern of each head in said one group of heads overlapping the spray pattern of a corresponding head in said other group of heads so that said substances can mix at a predetermined vertical distance from said heads to form said blanket.

21. The method of claim 18 further comprising the step of separately storing said gel-forming substance and said gel-inducing substance before they are delivered to said first group of branch conduits and said second group of branch conduits, respectively.

22. A method of fire protection comprising the steps of supporting a first and second group of conduits in an elevated position in a space to be protected from fire with the conduits of the first group extending in an alternating relationship with the conduits of the second group, connecting said conduits to a source of water, connecting a plurality of normally closed discharge heads to said conduits with each head being positioned substantially intermediate two adjacent branch conduits and connected thereto, selectively opening each head in response to a predetermined fire condition in its vicinity to permit said water to flow through said conduits to said heads, and separately delivering an aqueous gel-forming substance to said first group of conduits and an aqueous gel-inducing substance to said second group of conduits in response to said flow, said gel-forming substance and said gel-inducing substance mixing with said water to form a solution of gel-forming substance in said first group of conduits and solution of gel-inducing substance in said second group of conduits, said heads being constructed and arranged to mix said solutions and discharge same in the form of a fire extinguishing blanket of an aqueous gel material for goods stored in said space.

23. The method of claim 22 further comprising the step of separately storing said gel-forming substance and said gel-inducing substance before they are delivered to said first group of branch conduits and said second group of branch conduits, respectively.

24. A method of fire protection comprising the steps of connecting a group of normally closed discharge heads to a plurality of spaced parallel conduits, connecting said conduits to a source of water, selectively opening each head in response to a predetermined fire condition in its vicinity to permit said water to flow through said conduits for discharge from said heads, and selectively and intermittently delivering an aqueous gel-forming substance and an aqueous gel-inducing substance to said conduits in response to said flow for mixture with said water to form a solution of gelforming substance and a solution of gel-inducing substance, respectively, which flows to and is selectively and intermittently discharged from said heads to form a fire extinguishing blanket of an aqueous gel material for goods stored in said space.

25. The method of claim 24 further comprising the step of separately storing said gel-forming and gel inducing substance before they are delivered to said conduits, said gel-forming and said gel-inducing substances being selectively and intermittently released from said separate storage means into said water flowing through said conduits.

26. A method of fire protection comprising the steps of disposing a plurality of discharge heads in an elevated position in a space to be protected from fire, normally maintaining said heads in a closed condition, connecting said heads to a source of water by a single conduit system, selectively opening each head automatically in response to a predetermined fire condition in its vicinity to 'permit said water to flow through said conduit system to said head, separately storing a gelforming substance and a gel-inducing substance, and separately and intermittently injecting said gel-forming substance and said gel-inducing substance into said conduit system in response to said water flow to form a solution of gel-forming substance and a solution of 1 I S'IIATESEPATENT own I v Q CERTIFICATE v 0F CORRECTION PatentNo. 6 a d Siegtember 3, 1974 WILLIAM L. LIVINGSTON Inventofls) It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected. as shown below:

In claims .14, 15, 16, and 17, the dependency which reads "12-" should read .3. f

Claim 15, column 9, line 22, chahge "sotrage" to read. -sto rage-.

Signed and sealed this 17th day of December 1974.

(SEAL) Attest:

McCOY M. GIBSON JR. c. MARSHALLI'HDANN Attesting Officer Cqmissioner' of Patents

Claims

1. A fire extinguishing system comprising a plurality of normally closed discharge heads, conduit means supporting said heads in an elevated position in a space to be protected from fire, said conduit means connecting said heads to a source of water and comprising a first group of spaced parallel branch conduits for receiving one group of heads and a second group of spaced parallel branch conduits for receiving another group of heads, means associated with each head for opening said head in response to a predetermined fire condition in its vicinity to permit said water to flow through said conduit means for discharge from said heads, delivery means responsive to said flow for separately delivering an aqueous gel-forming substance to said first group of branch conduits and an aqueous gel-inducing substance to said second group of branch conduits, said gelforming substance and said gel-inducing substance mixing with said water to form a solution of gel-forming substance and a solution of gel-inducing substance which are delivered to said one group of heads and said other group of heads, respectively, said first and second groups of branch conduits extending in an alternating relationship along said space and the position of the heads on each branch conduit being staggered Relative to the position of the heads on its adjacent conduits to mix said solutions upon their discharge from said heads to form a fire extinguishing blanket of an aqueous gel material for goods stored in said space.

4. The system of claim 3 further comprising means for separately storing said gel-forming substance and said gel-inducing substance, said delivery means further including means for separately releasing said gel-forming and gel-inducing substances from said storage means to said first group of branch conduits and to said second group of branch conduits, respectively.

5. The system of claim 4 wherein said conduit means further comprises a first conduit connecting said source of water to said first group of branch conduits and a second conduit for connecting said source of water to said second group of branch conduits, said releasing means further comprising means for injecting said gel-forming substance and said gel-inducing substance into water flowing in said first and second conduits, respectively.

7. Te system of claim 1 wherein said gel-forming substance is polyvinyl alcohol and said gel-inducing substance is borax.

9. The system of claim 8 further comprising means for separately storing said gel-forming substance and said gel-inducing substance, said delivery means further including means for separately releasing said gel-forming and gel-inducing substances from said storage means to said first group of spaced parallel conduits and said second group of spaced parallel conduits, respectively.

13. A fire extinguishing system comprising a plurality of normally closed discharge heads disposed in an elevated position in a space to be protected from fire, conduit means connecting said heads to a source of water, means associated with each head for opening said head in response to a predetermined fire condition in its vicinity to permit said water to flow through said conduit means to said heads, delivery means responsive to said flow for selectively and intermittently delivering an aqueous gel-forming substance and an aqueous gel-inducing substance to said conduit means for mixture with said water to form a solution of gel-forming substance and a solution of gel-inducing substance, respectively, for selective intermittent discharge from each of said heads to form a fire extinguishing blanket of an aqueous gel material over goods stored in said space.

15. The system of claim 12 further comprising separate storage means for said gel-forming and gel-inducing substance, said delivery means being adapted to selectively and intermittently release said gel-forming and said gel-inducing substances from said separate sotrage means into said water flowing through said conduit means.

16. The system of claim 12 wherein said blanket flowingly envelopes said goods and substantially covers same.

17. The system of claim 12 wherein said gel-forming substance is polyvinyl alcohol and said gel-inducing substance is borax.

18. A method of fire protection comprising the steps of disposing a first group of conduits and a second group of conduits in an alternating relationship in an elevated position in a space to be protected from fire, connecting a first group of normally closed discharge heads to said first group of conduits, connecting a second group of normally closed discharge heads to said second group of conduits with the position of the heads on each branch conduit being staggered relative to the position of the heads on its adjacent conduits, connecting said conduits to a source of water, selectively opening each head in response to a predetermined fire condition in its vicinity to permit said water to flow through said conduits for discharge from said heads, separately delivering an aqueous gel-forming substance to said first group of conduits and an aqueous gel-inducing substance to said second group of conduits in response to said flow, said gel-forming substance and said gel-inducing substance mixing with said water to form a solution of gel-forming substance in said first group of conduits and a solution of gel-inducing substance in said second group of conduits, which flows to and is discharged from said first group of heads and said second group of heads, respectively, said solutions mixing upon their discharge from said heads to form a fire extinguishing blanket of an aqueous gel material for goods stored in said space.

24. A method of fire protection comprising the steps of connecting a group of normally closed discharge heads to a plurality of spaced parallel conduits, connecting said conduits to a source of water, selectively opening each head in response to a predetermined fire condition in its vicinity to permit said water to flow through said conduits for discharge from said heads, and selectively and intermittently delivering an aqueous gel-forming substance and an aqueous gel-inducing substance to said conduits in response to said flow for mixture with said water to form a solution of gel-forming substance and a solution of gel-inducing substance, respectively, which flows to and is selectively and intermittently discharged from said heads to form a fire extinguishing blanket of an aqueous gel material for goods stored in said space.

25. The method of claim 24 further comprising the step of separately storing said gel-forming and gel-inducing substance before they are delivered to said conduits, said gel-forming and said gel-inducing substances being selectively and intermittently released from said separate storage means into said water flowing through said conduits.

26. A method of fire protection comprising the steps of disposing a plurality of discharge heads in an elevated position in a space to be protected from fire, normally maintaining said heads in a closed condition, connecting said heads to a source of water by a single conduit system, selectively opening each head automatically in response to a predetermined fire condition in its vicinity to permit said water to flow through said conduit system to said head, separately storing a gel-forming substance and a gel-inducing substance, and separately and intermittently injecting said gel-forming substance and said gel-inducing substance into said conduit system in response to said water flow to form a solution of gel-forming substance and a solution of gel-inducing substance, respectively, for discharge from said heads at predetermined intervals, said solutions mixing to form a fire extinguishing blanket of an aqueous gel material for goods stored in said blanket.