Abstract:
A fire suppression system may include a tank and a manifold in the tank. The tank, when charged, holds a liquid pressurized with a gas. The manifold has an inlet coupled to receive a liquid flow from a lower portion of the tank and an inlet configured to receive a gas flow from a upper portion of the tank. An expansion chamber in the manifold receives the liquid flow and the gas flow and is shaped to mix the liquid and gas flows and thereby produce foam.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This patent document is claims benefit of the earlier filing date of U.S. provisional Pat. App. No. 62/311,166, filed Mar. 21 2016, which is hereby incorporated by reference in its entirety. 
     
    
     BACKGROUND 
       [0002]    Conventional CAFSs (Compressed Air Foam Systems) for fire suppression generally create foam by mixing a liquid solution containing water and foam concentrate from an extinguisher tank with an air flow from either an air compressor or a high-pressure air cylinder, e.g., a flow from a cylinder pressurized to about 3200 psi to 6000 psi regulated down to a safe working pressure. The compressor or high-pressure air cylinder can be cumbersome, difficult to maintain, and adds to the cost of the fire suppression system. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0003]      FIG. 1  shows an implementation of a two-piece manifold including an expansion chamber for generating fire suppressing foam. 
           [0004]      FIG. 2  shows an implementation of a fire suppression system having a manifold including an expansion chamber installed within a pressurized tank. 
           [0005]      FIG. 3  shows a manifold in accordance with an implementation using air inlets of different sizes. 
           [0006]      FIG. 4  shows a manifold in accordance with an implementation using inlets with replaceable jets. 
           [0007]      FIGS. 5A and 5B  show perspective views of a manifold in accordance with an implementation having removable jets and storage pockets for the jets. 
       
    
    
       [0008]    The drawings illustrate examples for the purpose of explanation and are not of the invention itself. Use of the same reference symbols in different figures indicates similar or identical items. 
       DETAILED DESCRIPTION 
       [0009]    A CAFS (Compressed Air Foam System) with an in-tank manifold including an expansion chamber may eliminate the need for a high-pressure air cylinder or other gas supply separate from a tank containing a foam solution. A CAFS fire extinguisher may thus avoid drawbacks of high-pressure cylinders, which add to the system costs and can be cumbersome and difficult to refill. Accordingly, a CAFS System with an in-tank manifold may be smaller, lighter, less expensive, and easier to use and maintain than a conventional CAFS System. 
         [0010]      FIG. 1  shows an in-tank manifold  100  for a CAFS system in accordance with one implementation of the invention. Manifold  100  may be sized to fit inside the tank of a conventional fire extinguisher, and in one specific implementation may be about 4 to 5 inches long and about 1 to 1.25 inches in diameter, which allows insertion or removal of manifold  100  through the top opening in many conventional fire extinguisher tanks. In the illustrated configuration of  FIG. 1 , manifold  100  includes two major pieces  110  and  120 , which may be made from any material of suitable strength and temperature tolerance. For example, manifold pieces  110  and  120  may be machined or otherwise made from a metal such as aluminum or stainless steel or from a high-strength plastic. Pieces  110  and  120  are shaped to fit together to create or define an expansion chamber  130  for mixing of gas and solution to produce foam.  FIG. 1  shows an implementation in which pieces  110  and  120  have mating portions that slip together, and one or more set screws  125  holds pieces  110  and  120  in place. An o-ring seal  115  between pieces  110  and  120  may prevent unwanted fluid flow into or leakage between manifold pieces  110  and  120 . Alternatively, pieces  110  and  120  may be screwed together by threads or close fit and pressed together as described below, which may also prevent unwanted flow or leakage between manifold pieces  110  and  120  without need of an o-ring. The two-piece construction of manifold  100  has the advantage of permitting machining of manifold pieces  110  and  120  to provide expansion chamber  130  with a diameter larger than the diameters of the inlets and outlets of expansion chamber  130 . Alternatively, casting or molding may be able to produce a one-piece construction for a manifold including an expansion chamber. 
         [0011]    Expansion chamber  130  is created when manifold piece  120  threads, slips, or is pressed onto manifold piece  110 . Expansion chamber  130  may be cylindrical. Expansion chamber  130  as shown in  FIG. 1  has one or more inlets  132  for liquid, one or more inlets  134   a  and  134   b  for gas, and one or more outlets  136  for foam. Liquid inlet  132  of manifold  100  is shaped to engage a dip tube, which may provide a feed of a water/concentrated foam mix. In the illustrated configuration, liquid inlet  132  is in bottom piece  110  of the manifold  100  and has threads, e.g., standard ½″ pipe thread, into which a dip tube may be threaded. Expansion chamber  130  may have an interior diameter larger than an interior diameter of inlet  132 , so that expansion or turbulence occurs when foam concentrate enters expansion chamber  130  through inlet  132 . More particularly, expansion chamber  130  and inlet  132  may be sized to provide an interior pressure in expansion chamber  130  that is suitably less than the pressure of the solution entering through inlet  132 . For example, expansion chamber  130  may have an interior diameter of about 1 inch when inlet  132  has an interior diameter restricted to about ½ inch. 
         [0012]    A bottom gas inlet  134   a  into expansion chamber  130  may be offset and/or at an angle, e.g., at 30°, with the fluid flow into expansion chamber  130 , and a top gas inlet  134   b  may similarly be offset and/or at an angle, e.g., at 30°. The offsets or angles of inlets  134   a  and  134   b  relative to liquid inlet  132  may vary but may assist in creating a liquid-gas vortex in expansion chamber  130 , which may help mix liquid from inlet  132  and gas from inlets  134   a  and  134   b  to create foam. In the implementation of  FIG. 1 , bottom air inlet  134   a  is in manifold piece  110  and top air inlet  134   b  is in manifold piece  120 , but other configurations are possible. With the configuration of gas inlets  134   a  and  134   b  shown in  FIG. 1 , top inlet  134   b  may shoot a stream of air down into expansion chamber  130  and bottom inlet  134   a  may shoot a stream of air up into expansion chamber  130 , which may create a vortex that helps expand the foam chemical and water solution entering through liquid inlet  132  in manifold piece  110 . 
         [0013]    Foam created in expansion chamber  130  flows out of foam outlet  136 , which in the illustrated configuration is formed in manifold piece  120 . A restriction or reduced diameter hole may be provided in outlet  136  to enhance a pressure differential between outlet  136  and expansion chamber  130 , which may also increase or improve turbulence, expansion, or mixing in chamber  130 . For example, a restriction in outlet  136  may be about ⅜ inches in diameter when expansion chamber  130  is about 1 inch in diameter. Foam outlet  136  may thread into a release valve of a fire suppression system, e.g., into a standard squeeze handle of the 2½ gallon stainless steel water fire extinguisher. The release valve may be opened to start liquid and gas flow into expansion chamber  130  and to release the foam from expansion chamber  130 . 
         [0014]      FIG. 2  illustrates a fire suppression system  200  in accordance with an implementation using in-tank manifold  100  of  FIG. 1 . In system  200 , manifold  100  attaches to a squeeze handle  210 .  FIG. 2  shows a specific implementation in which manifold  100  is threaded into a fitting  260  for a pressure relief valve, and fitting  260  attaches squeeze handle  210  to a tank  220 . Alternatively, the foam outlet of manifold  100  may directly thread into squeeze handle  210 . In either case, squeeze handle  210  with or without fitting  260  attaches to and seals tank  220  in a conventional manner for fire extinguishers so that tank  220  may be pressurized to a desired working pressure while manifold  100  is within tank  220 . As shown in  FIG. 2 , tank  220  includes a single compartment that is partially filled with an aqueous foam concentrate  240 , e.g., Class A foam concentrate, aqueous film forming foam (AFFF) concentrate, or polar solvent foam concentrate mixed with water, and is pressurized with a gas  250 , e.g., air at about 100 to 300 psi or more. Tank  220  may, for example, be a 2½ gallon stainless steel tank such as commonly employed for some fire extinguishers, but tank  220  may alternatively be of any size and construction capable hold liquid and gas under suitable pressure. 
         [0015]    Manifold  100  in the illustrated embodiment is near the top of tank  220  and in the gas filled portion of tank  220 , and a dip tube  230  threads into the liquid inlet of manifold  100  and extends into a liquid filled portion of tank  220  and particularly down to near the bottom of a tank  220 . In operation, a user depresses a portion of squeeze handle  210  opening a valve so that the higher pressure in tank  220  forces liquid  240  and gas  250  toward the lower pressure outside tank  220 . Liquid  240  particularly flows up dip tube  230  and into expansion chamber  130 . Since manifold  100  and its gas inlets are above the level of liquid  240 , gas  250  flows through the gas inlets of manifold  100  into mixing/expansion chamber  130 . The mixing of liquid  240  and gas  250  in chamber  130  forms fire suppressant foam that exits through squeeze handle  210  and a nozzle that can direct the foam for fire suppression. 
         [0016]    Tanks used in current pressurized fire extinguishers are commonly hydro-tested up to 300 psi and are rated for working pressures of about 100 psi to 160 psi. Operating system  200  at a higher pressure up to 200 or 300 psi or more allows system  200  to be filled with a greater volume of liquid  240 , while pressure of gas  250  maintains a strong stream of foam from system  200 . System  200  may thus be able to provide more suppressant foam than do conventional CAFS extinguishers. 
         [0017]      FIG. 3  shows an in-tank manifold  300  including a bottom piece  310  and a top piece  320  in accordance with another implementation. Manifold  300  may include many of the same features as described above for manifold  100 . In particular, pieces  310  and  320  connect together to form an expansion chamber  130  having an liquid inlet  132  and a foam outlet  136 , which may have the characteristics described above.  FIG. 3  further illustrates how manifold  300  may include multiple gas inlets  331 ,  332 ,  333 , and  334  having fixed or drilled sizes, which may be different. For example, one inlet  331  may provide the smallest diameter or area gas inlet to expansion chamber  130 , inlet  332  may be larger than inlet  331 , inlet  333  may be larger than inlet  332 , and inlet  334  may provide the largest diameter or area gas inlet to chamber  130 . The increasing size may be in an order that directs a mixing circulation of liquid and gas in chamber  130 . 
         [0018]      FIG. 3  also illustrates how manifold pieces  310  and  320  may be threaded together to create a chamber  130  that is larger than its inlets and outlets. 
         [0019]      FIG. 4  shows an in-tank manifold  400  that may include many of the same features as described above for manifold  100  or  300 . In particular, pieces  410  and  420  of manifold  400  connect together to form an expansion chamber  130  having an liquid inlet  132  and a foam outlet  136 , which may have the characteristics described above. Manifold  400  also includes a series of threaded gas inlets  431 ,  432 ,  433 , and  434  in manifold pieces  410  and  420  and sized for installation of replaceable jets  441 ,  442 ,  443 , and  444 . For example, an Allen wrench can be used to install jets  441  to  444  in respective gas inlets  431  to  434  or remove the jets from the gas inlets. Each installed jet  441 ,  442 ,  443 , and  444  has an orifice that limits the gas or air flow through the corresponding inlet  431 ,  432 ,  433 , and  434 . The orifices in jets  441 ,  442 ,  443 , and  444  may all be the same size, or one or more of jets  441 ,  442 ,  443 , and  444  may have different sizes. In some configurations, one or more of jets  441 ,  442 ,  443 , and  444  may be omitted, and the diameters of inlets  431 ,  432 ,  433 , and  444  without a jet defines a maximum orifice size. In one configuration, the orifices may be about 1/16 inch in diameter or smaller and inlets  431  to  424  may be about ¼ inch in diameter. Depending on the orifice size or sizes in the installed jets  441 ,  442 ,  443 , and  444 , manifold  400  may produce a drier or wetter foam. In particular, jets with a smaller orifices may be employed when a wetter foam is desired, or jets with larger orifices may be employed when a drier foam is desired. 
         [0020]    Jets  441 ,  442 ,  443 , and  444  installed in inlets  431 ,  432 ,  433 , and  434  may be chosen to achieve the same effects as described above for manifold  300  of  FIG. 3 . For example, in the direction of circulation in chamber  130 , jet  441  may have the smallest diameter or area orifice, jet  442  may have a larger orifice than does jet  441 , jet  443  may have a larger orifice than does jet  442 , and jet  444  may have the largest diameter or area orifice. The increasing size of the orifices and increasing air flows that result may be in an order that directs a mixing circulation of liquid and gas in chamber  130 . 
         [0021]      FIG. 4  also illustrates how manifold pieces  410  and  420  may be tight fit and pressed together to create an expansion chamber  130  that is larger than inlets and outlets of expansion chamber  130 . In particular, one manifold piece  410  or  420  may have a male mating portion with an outside diameter that is the same as or slightly larger than an inside diameter of a female mating portion of the other manifold piece  420  or  410 . During manufacture of manifold  400 , mating portions of manifold pieces  410  and  420  may be aligned, and a vise or press may apply pressure to force one mating portion into the other. If desired manifold  410  or  420  with the female mating portion may be heated. In any case, the tight fit may hold manifold pieces together without need of threads or a set screw. 
         [0022]      FIGS. 5A and 5B  show exterior views of a manifold  500  that may have the same features as the manifolds described above. In particular, manifold  500  includes two pieces  110  and  120  that engage each other to create a mixing or expansion chamber having one or more liquid inlet  132 , one or more gas inlet  134   a  and  134   b,  and one or more foam outlet  136 . Gas inlets  134   a  and  134   b  in manifold  500  extend through piece  110  or  120  to the expansion chamber and are threaded. Accordingly, jets may be screwed into either gas inlets  134   a  and  134   b  to control the size of the orifices through which gas flows into the expansion chamber. Manifold  500  further includes pockets  534   a  and  534   b  that may have the same threading as gas inlets  134   a  and  134   b  but do not extend through piece  110  or  120  to the expansion chamber. Accordingly, no gas flows through pocket  534   a  or  534   b,  but a jet may be screwed into either pocket  534   a  or  534   b  for storage when not in use. For example, manifold  500  may come with multiple jets with different size orifices for use in inlets  134   a  and  134   b,  and a user may select jets according to whether a drier or a wetter foam is desired. The user can then screw selected jets into gas inlets  134   a  and  134   b  and screw the spare jets into pockets  534   a  and  534   b.  Alternatively, manifold  500  may have a single jet for each gas inlet  134   a  or  134   b  and may give a user the option to use the jets in gas inlet  134   a  and  134   b  to restrict air flow into the mixing or expansion chamber or screw the unused jets into pocket  534   a  or  534   b  for unrestricted flow through gas inlets  134   a  or  134   b.    
         [0023]    Although particular implementations have been disclosed, these implementations are only examples and should not be taken as limitations. Various adaptations and combinations of features of the implementations disclosed are within the scope of the following claims.