Patent Publication Number: US-3876010-A

Title: Foam fire-extinguishing device for walled containers

Description:
United States Patent Blomquist et al.  
 [ FOAM FIRE-EXTINGUISHING DEVICE FOR WALLED CONTAINERS [75] Inventors: David L. Blomquist. Martinez;  
 Frederick W. Almus, San Anselmo both of Calif.  
 [73] Assignee: Chevron Research Company, San  
 Francisco, Calif [22] Filed: Dec. 26, 1973 {21] Appl. No.: 427,870  
 [52] US. Cl 169/46; 169/68 [51] Int. Cl. A62c 3/12 [58] Field of Search 169/43, 46. 47, 66, 68, 169/89 [561 References Cited UNITED STATES PATENTS 1,364,799 1/1921 Patterson et al 169/68 2.341,436 2/1944 Getz 169/68 X 2514.439 7/1950 Boyd et al 169/68 2.772.743 12/1956 Eggleston 169/68 Apr. s, 1975 [57] ABSTRACT Apparatus comprising a liquid storage container and a foam dispensing fire-extinguishing means wherein the container has at an upper portion of the wall thereof an elongated, substantially continuous substantially horizontal foam inlet slot. and wherein the fireextinguishing means comprises an elongated substantially horizontal foam distribution channel communieating with the foam inlet slot along substantially the entire length of the foam inlet slot the fireextinguishing means further comprising foam generator means and conducting means for conducting foam from the foam generator to the distribution channel Also. a process for quenching fires in a flammable liquid storage container by passing foam down the interior wall of the container in a substantially continuous curtain from at least one substantially horizontal foam inlet slot located in and through and substantially around the container wall at an upper portion thereof.  
 12 Claims, 3 Drawing Figures FOAM FIRE-EXTINGUISI-IING DEVICE FOR WALLED CONTAINERS BACKGROUND OF THE INVENTION l. Field of the Invention There exists a continuing need for improved methods for fighting fires in walled containers holding flammable liquids. Many means have been used for discharging foam for fighting fires in walled containers. e.g.. tanks with or without floating roofs.  
  As pointed out in US. Pat. No. 2.772.743, many devices for discharging a stream of foam onto the surface of a liquid have been found to be unsatisfactory because of a tendency for the foam to break down under the agitation accompanying direct impingement of the foam upon the surface of the liquid or against the means used for spreading the foam. Because of foam breakdown, a discontinuous foam blanket results with a concomitant decreased efficiency in putting out the fire.  
  An additional problem with floating roof tanks arises from the location of the foam discharge system on the interior wall of the tank or on the floating roofitself. In the former case. a foam discharge system mounted on the interior wall of the tank will interfere with the movement of the roof as it adapts to various levels of liquid in the container. In the latter case. where the foam discharge system is mounted on the floating roof, it is inoperable if the roof sinks.  
  The subject invention is directed to an apparatus and process for fighting fires in a walled liquid container by use of a system which can be operated without anyone approaching the container, will put foam around the wall of the container forcing the fire toward the center of the container. does not become inoperative if the roof sinks. is readily accessible for inspection and testing. will not interfere with men fighting a floating roof seal fire by auxiliary means. provides foam flow on a continuous basis to substantially cover the entire inner wall surface in a continuous curtain. and is operative with substantially all walled containers used for holding flammable liquids.  
 2. Description of the Prior Art As previously mentioned. many means have been used for discharging foam onto the surface of a burning liquid. For example. US. Pat. No. 2.772.743 discloses a foam discharge conduit located on the interior wall of a liquid storage tank. The patent teaches the use of several discharge conduits circumferentially spaced on the tank wall (sec column 3. lines 63-68).  
  US. Pat. No. 2.548.409 discloses a fire extinguishing system which distributes foam to extinguish seal fires in the floating roof storage tank. The foam supply is externally located relative to the tank and supplies foam to conduits located on the floating roof.  
  US. Pat. No. l.294.776 discloses a fire extinguishing system for oil fires which distributes atomized carbon tetrachloride from a ring-shaped manifold.  
  Additional patents relating to extinguishing fires and storage tanks are US. Pat. Nos. l.307.6l4 and [386.232.  
 SUMMARY OF THE INVENTION The subject invention is directed to apparatus comprising a liquid storage container and a foam dispensing fire-extinguishing means wherein the container has at an upper portion of the wall thereof an elongated. substantially continuous. substantially horizontal foam inlet slot. and wherein the fire-extinguishing means comprises an elongated substantially horizontal foam distribution channel communicating with the foam inlet slot along substantially the entire length thereof. The fire-extinguishing means further comprises foam generator means and conducting means for conducting foam from the foam generator to the distribution channel.  
  Also encompassed within the suject invention is a process for quenching fires in a flammable liquid storage container by passing foam down the interior wall of the container in a substantially continuous curtain from at least one substantially horizontal foam inlet slot lo cated in and through and substantially around the container wall at an upper portion thereof.  
 DETAILED DESCRIPTION OF THE INVENTION Drawings FIG. 1 is a perspective of a section of a walled container (a tank with floating roof) showing the fireextinguishing means.  
  FIG. 2 is an elevation view of an alternative distribu tion channel and foam inlet slot which comprises part of the fire-extinguishing means.  
 FIG. 3 is a cross-section along line 3-3 of FIG. 2.  
 STATEMENT OF THE INVENTION As summarized above. the subject invention is directed to an apparatus comprising a walled liquid storage container and a foam dispensing fire-extinguishing means. The fire-extinguishing means comprises an elongated substantially horizontal foam distribution channel communicating with the foam inlet slot along substantially the entire length of the slot. The fireextinguishing means further comprises a foam generator means and conducting means for conducting the foam from the generator to the distribution channel. Preferably. the fire-extinguishing means is mounted at an upper portion of the wall of the container and on the outside thereof.  
  By substantially continuous. substantially horizontal foam inlet slot&#34; is meant that the slot completely surrounds the liquid storage container. except for small interruptions in the slot so that continuity may be preserved and for increased structural strength. and is sufficiently close to being horizontal to provide a continuous curtain of foam being formed and by gravity flow ing down the wall of the container. reaching the desired location, tag. the surface of the burning liquid or the roof of the tank at substantially the same time completely around the vessel. This avoids the situation where a discontinuous foam blanket is provided to the desired location resulting in inefficient fire fighting.  
  A preferred embodiment of the subject invention is the apparatus described above wherein the foam distribution channel is constructed and arranged to channel foam introduced thereinto substantially completely around the container as a foam reservoir before the foam overflows through the inlet slot into the container.  
  The subject invention also encompasses a process for quenching fires in a flammable liquid storage container which comprises passing foam down the interior wall of the container in a substantially continuous curtain from at least one substantially horizontal foam inlet slot located in and through and substantially around the container wall at an upper portion thereof. Preferably, the process is carried out by forming a substantially horizontal elongated collar of foam substantially around the container (tank) at an upper portion thereof before the foam is passed down the interior wall of the container in a substantially continuous curtain.  
  The subject invention may be more fully understood from the following description when read in conjunction with the drawings which teach preferred embodiments of the subject invention.  
  Referring first to FIG. I, a portion of the circular tank having a wall 1, a walkway 2 and a floating roof 3, is shown. The floating roof 3 has a tube seal 4, a weather shield 5, a foam darn 6, with drain slots 7. At the top of the tank wall there is a foam inlet slot 8. As shown in FIG. I, the foam inlet slot 8 is elongated, substantially continuous and substantially horizontal. Foam distribution channel 9 serves to distribute foam around the circumference of the tank. Foam solution is introduced by line 10. manifold 11, and pipes 12 and 13 to foam generators I4 and 15. The generated foam is then sent via lines 16 and 17 to foam nozzles 18 and 19. As shown in FIG. I {specifically referring to nozzle 19). the nozzles have openings in the end portions thereof and a slit 20 along the length thereof. As the foam is generated. it is distributed around the foam distribution channel 9. When it reaches a sufficient depth. it overflows through slot 8 down the interior wall of the tank in the direction shown by the heavy dark arrows in FIG. I. The foam forms a substantially continuous curtain as it flows down the wall of the tank 1 over weather shield 5 and then to the area of the fire at tube seal 4. Note that foam dam 6 prevents free-flow of the foam over the entire surface of the floating roof. Rather, the foam is directed to the point of maximum utilization. i.e.. the tube seal where fire is most likely to occur. Once sufficient foam has filled up to overflow foam dam 6. the foam will spread out and cover the entire root&#34; surface.  
  Referring now to FIG. 2, an alternative preferred apparatus is shown. In FIG. 2, only the foam distribution channel. horizontal foam inlet slot and conducting means for conducting foam from the foam generator to the distribution channel. is shown. Specifically, a pipe 21 (the conducting means) from the foam generator feeds foam to horizontal foam distribution channel 22 which comprises a pipe having a substantially continuous aperture 23 therein located about 45 above a horizontal plane passing through the center line of said pipe. The aperture 23. as depicted in FIG. 3 which will be discussed hereinafter. is preferably in the quadrant of the pipe (when shown in cross-section) toward the vertical portion of the foam deflector 24. The foam flows out of aperture 23 down the vertical wall of foam deflector 24 and out the slot 25 formed by foam deflector 24 and the tank wall 26.  
  This preferred embodiment is better understood by referral to FIG. 3, which is a cross-section along line 3-3 in FIG. 2. The foam introduced into foam distribution channel 22 flows out of slot 23 into a space defined by foam distribution channel 22 and foam deflector 24, falls by gravitational force until it reaches slot 25 formed by foam deflector 24 and the wall of the tank 26, and then flows down the wall of the tank. The direction of foam flow is shown by the heavy black arrows in FIG. 3. The nut and bolt 27 upon which foam distribution channel 22 rests can be adjusted to orientate the foam distribution channel 22 in a substantially horizon tal position. After leveling, the nut and bolt are preferably welded to hold the channel in place.  
  It should be noted that the numeral 23 has been used to refer to the aperture in foam distribution channel 22. By aperture 23&#34; is meant the perforations through which foam leaves foam distribution channel 22 and flows into the space defined by foam distribution chan nel 22 and foam deflector 24. By providing smaller openings at the point where pipe 21 intersects foam distribution channel 22, the situation is avoided where foam preferentially is dispelled at that portion of the foam distribution channel thereby resulting in uneven distribution of the foam to the inlet slot 25.  
  It should be noted that FIG. 1 shows only two foam generators. Around the wall of the tank several more will be used. For example, in a tank with a diameter of 110 feet. there would preferably be 6 T-nozzles of the type shown in FIG. 1 evenly distributed, i.e.. one approximately every feet around the tank circumference.  
  It is apparent that many different embodiments of this invention may be made without departing from the scope and spirit thereof and. therefore. it is not in tended to be limited except as indicated in the appended claims.  
 What is claimed is:  
  l. Apparatus comprising a walled liquid storage container and a foam-dispensing fire extinguishing means. said container having at an upper portion of the wall thereof an elongated. substantially continuous, substantially horizontal foam inlet slot. said fire extinguishing means comprising an elongated substantially horizontal foam distribution channel communicating with said foam inlet slot along substantially the entire length of said foam inlet slot, said fire extinguishing means further comprising foam generator means and conducting means for conducting foam from said foam generator to said distribution channel.  
  2. Apparatus as in claim I wherein said fire extinguishing means is mounted at an upper portion of said wall on the outside of said container.  
  3. Apparatus as in claim 2 wherein said foam distribution channel substantially surrounds said container, and wherein said foam distribution channel is so constructed and arranged to channel foam introduced thereinto substantially around said container as a foam reservoir before said foam overflows through said inlet slot into said container.  
  4. The apparatus of claim 1 wherein said horizontal foam distribution channel is a pipe having a substantially continuous aperture therein and deflector means for directing foam to said inlet slot.  
  5. Apparatus for quenching fires in a walled liquid storage container, said container having in and through an upper portion of the wall thereof at least one elongated substantially horizontal foam inlet slot, which comprises substantially horizontal elongated channel means located outside said wall adjacent to said slot and in communication with said slot along substantially the entire length thereof. said channel means being so constructed and arranged with respect to said walls and said slot that foam introduced therein will flow substantially throughout the length of said channel means before flowing from said channel means through said slot into said container, and means for introducing foam into said channel means.  
  6. Apparatus as in claim 5 wherein said means for introducing foam into said channel means comprises a foam generator.  
  7. A storage tank for liquid hydrocarbons comprising in combination at least one substantially horizontal elongated fire-quenching foam inlet slot located in and through and substantially completely around the wall of said tank at an upper portion thereof. and a substantially horizontal elongated foam distribution channel surrounding said tank adjacent to said inlet slot, said channel communicating with said slot along substantially the entire length thereof and so constructed and arranged with respect to said slot that foam introduced into said channel will flow substantially along the entire length thereof before reaching a sufficient depth to overflow into said tank through said slot, and means for introducing foam into said channel.  
  8. A tank as in claim 6 wherein said means for introducing foam into said channel comprises a foam generator.  
  9. A tank as in claim 6 further comprising a floating roofand foam dam means for directing said foam to the seal area of said floating roof.  
 [0. Apparatus for quenching fires in a hydrocarbon liquid storage tank which comprises means located outside said tank for forming a substantially horizontally elongated collar of foam substantially around said tank at an upper portion thereof, at least one substantially horizontal foam inlet slot located in and through and substantially around the wall of said tank at an upper portion of said wall. and means for passing said foam through said inlet slot and thence down the interior of said wall in a substantially continuous curtain.  
  ll. A process for quenching fires in a flammable liquid storage container which comprises (l) generating foam, (2) distributing said foam around the exterior of said container at an upper portion thereof and (3) passing said foam down the interior wall of said container in a substantially continuous curtain from at least one substantially horizontal foam inlet slot located in and through and substantially around the container wall at an upper portion thereof.  
  12. The process of claim 10 wherein a substantially horizontally elongated collar of foam is formed substantially around said tank at an upper portion thereof, and is then passed through said inlet slot and thence down the interior of said wall in a substantially continuous curtain.