Abstract:
A compressed air/foam fire fighting system which is sufficiently compact to be carried on the bed of a pick-up truck includes a water tank, a pump for providing water at substantial pressure to a water conduit, an engine for driving the pump, a foam reservoir including a bladder tank connected to the pump, an air compressor, an engine for driving the air compressor, a differential pressure valve connected in the water conduit, a metering valve adjustable to supply a desired proportion of foam concentrate to water connected across the differential pressure valve, an air valve for controlling the amount of air from said compressor, and an air injection venturi for mixing air into a water/foam concentrate. A two-way valve connected between the tank and the pump is movable between a first position where water is pumped from the water tank and a second or suction position where water is drawn from an outside tank or other source. The system can supply plain water, a water/foam mixture, a mixture of compressed air, water, and foam, or compressed air only.

Description:
REFERENCE TO RELATED APPLICATION 
   This Non-Provisional Patent Application is based upon U.S. Provisional Patent Application Ser. No. 60/409,717 filed Sep. 10, 2002, and hereby claims the benefit of the embodiments therein and of the filing date thereof. 

   FIELD OF THE INVENTION 
   This invention relates to the field of fire fighting, and more particularly, to compressed air foam systems (CAFS) for controlling the flow of fire fighting fluids which employ foam-producing additives to water to be delivered by a hose from a pressurized source, such as a pump, a fire hydrant, or from such other sources, such as a tank, a stream or a lake. 
   BACKGROUND OF THE INVENTION 
   There are many situations where it would be desirable to have a compact, relatively portable fire-fighting system readily available, particularly in forest or brush areas or in remotely located neighborhoods where full scale fire-fighting equipment is not readily available or accessible. Such a compact system should, to the extent possible, make use of the most advanced fire-fighting technology available. 
   The use of foam additives to water in fighting fires is well recognized as a major advance in improving the effectiveness in retarding ignition, extinguishing blazes, preventing re-ignition of burnable materials, and in indicating a coverage in both airborne drops and ground operations. Foam is particularly suited for use in forest or brush areas where it will also act as a wetting agent, exhibiting good cooling capability by blanketing burnable materials, and reducing smoke by the blanketing effect. 
   This system employs our previously patented foam mixing system, which is the subject of U.S. Pat. No. 5,009,244, assigned to the assignee of the present patent application, which discloses a system for mixing foam concentrate, such as a product of Ansul Wormold Corp. of Marionette, Wis., sold under the trademark ANSUL, with water in such a way that the precise desired proportion of foam concentrate is mixed with water irrespective of the quantity of water supplied to fight a fire. A significant element of this system is a differential pressure valve, the subject of U.S. Pat. No. 5,165,442, which is also assigned to the assignee of the present application. Both of the above patents are hereby incorporated by reference. 
   Fire fighters are concerned with the ratio of foam concentrate to water and also to the ratio of water/foam concentrate to air. If the foam concentrate provided is too low (below about 0.2%), this will result in pulsations (water slugs) in the hose. This is because there is not enough foam concentrate in the solution to form foam in the hose. A somewhat higher ratio will yield a “wetter” appearing foam. A still higher ratio will yield a “drier” appearing foam. Varying degrees of dryness or wetness are appropriate for combating different types of fires. 
   Because the ratio of air to water/foam solution is recognized as being very important to getting the desired type of foam output, other systems have used separate flow meters for air and for the water/foam concentrate mix. This arrangement is difficult to operate because it leaves one operator, the engineer, juggling the air and water/foam valves in an attempt to produce the desired output at the end of the hose, while the second operator, the firefighter, at the end of the hose may well be out of sight and out of earshot. So, although the second operator might recognize that the ratio was not what was needed (more or less water/foam concentrate in proportion to air), he might have difficulty conveying to the operator the need for and the kind of change needed for controlling the flow. 
   It is, therefore, an object of the present invention to provide a compressed air foam fire-fighting system having controls capable of setting and maintaining desired ratios of water/foam concentrate to compressed air. 
   It is another object of the present invention to provide a fire-fighting system incorporating the above objective, and in which the entire system is built into a framework small enough to fit in the bed of a typical full size pick-up truck. 
   It is a further object of the present invention to provide a fire-fighting system incorporating the above objectives and in which the ratio of foam concentrate to water is maintained irrespective of a volume of water delivered to the system. 
   It is a still further object of the present invention to provide a fire-fighting system incorporating the above objectives and which is capable of delivering water, water/foam concentrate, water/foam concentrate mixed with compressed air and air alone. 
   Other objects and advantages will become apparent from consideration of the following specification taken in connection with the accompanying drawings. 
   BRIEF SUMMARY OF THE INVENTION 
   This invention involves a universal fire fighting system, which is designed to be easily transportable by fire fighting personnel to a fire scene where the use of compressed air, foam/water fluids, as well as water alone or aspirated foam/water fluid, is used. The water may be supplied by a portable or fixed tank, a hydrant, or from another water source, such as a lake, stream or a swimming pool. 
   The system, which can be carried on a pick-up truck, includes two small internal combustion engines, one of which drives a water pump, which may be connected to an integral tank or another water source and the other, which drives the air compressor for the system. Each engine has separate, independent controls. A control panel accessible at the rear of the pick-up truck contains controls for the engines, such as ignition and starter switches and choke and throttle controls. A number of gauges are included and switches for controlling the rate of flow of water, water/foam concentrate or compressed air. Valves are included for controlling water input, water or aspirated foam output, or compressed air/foam or air only outputs and a water drain line. 
   The patented foam mixing system of U.S. Pat. No. 5,009,244 includes a metering valve which can be positioned or set to provide a precisely metered proportion of foam concentrate to water. A differential pressure valve applies discharge water pressure to the foam concentrate as a function of the flow through the main water line. In this manner, the system acts to maintain the desired proportion of foam concentrate to water irrespective of the volume of water delivered. Where only a water/foam solution is desired, this solution is supplied to a specific discharge conduit, including a two-way valve. 
   When it is desired to combine the water/foam solution with air, the two-way valve controlling the output of water or water/foam solution is closed and the water/foam solution from the differential pressure valve is supplied to a foam solution metering valve which includes a movable plate having a plurality of ports, each calibrated to a different desired flow rate. The output of the foam solution-metering valve is then fed to an air injection venturi that includes ports for the injection of air into the foam solution from the foam solution-metering valve. 
   Air, under a substantial known pressure, is supplied by an engine-driven compressor and is fed to an air metering valve which includes a movable plate having a plurality of ports calibrated to supply compressed air in measured quantities at a known pressure. This selected airflow is connected to the air injection venturi which includes a series of ports at the throat of the venturi through which the air is injected. Thus, it will be understood that with precisely calibrated ports in both the foam solution metering valve and the air valve, the ratio of foam solution to air is controlled and maintained, and the system operators can rely on the ratio remaining and the system operators can rely on the ratio remaining as selected. 
   The modes of operation of this system are:
         1. to supply water at the desire flow rate, either
           a) from a self-contained tank or a tank on an associated vehicle; or   b) from an external source, such as a lake, stream, or swimming pool;   
           2. to supply a controlled ratio of foam concentrate mixed with water, which ratio remains essentially the same irrespective of the rate of water flow selected;   3. to supply controlled ratios of compressed air mixed with foam concentrate and water; and   4. to supply compressed air only.       

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     This invention may be more clearly understood from the following detailed description and by reference to the drawings in which: 
       FIG. 1  is a perspective view of a truck-mounted system of this invention; 
       FIG. 2  is a schematic block diagram of this invention; 
       FIG. 3  is a schematic drawing of the foam supply system of  FIG. 2  on an enlarged scale; 
       FIG. 4  is an exploded view of the foam selector metering valve; 
       FIG. 5  is a plan view of the metering disk of  FIG. 4 ; 
       FIG. 6  is a vertical sectional view of the foam selector metering valve of  FIG. 4 ; 
       FIG. 7  is a perspective view of the foam selector metering valve of  FIGS. 5–7 ; 
       FIG. 8  is a vertical sectional view of the air metering valve; 
       FIG. 9  is a sectional view taken along line  9 — 9  of  FIG. 8 ; 
       FIG. 10  is a vertical sectional view of the air injection venturi of the invention; 
       FIG. 11  is a sectional view taken along line  11 — 11  of  FIG. 10 ; and 
       FIG. 12  is a front elevational view of the control panel of the invention. 
   

   DETAILED DESCRIPTION 
   Referring now to  FIG. 1 , applicants&#39; fire fighting system  10  is shown carried in the bed of a pick-up truck PT. The system  10  is a complete integrated system mounted on and secured to a frame and includes a control panel  11  readily accessible from the back of the pick-up. Also carried in the bed of pick-up truck PT are a water tank  12  and a hose reel  14 . All inlet and outlet port valves are located on the control panel. 
     FIG. 2  is a schematic block diagram of the system  10  in which engine E 1  drives a water pump  18 , which is connected to water tank  12  through a pipe  19  and a two-way valve  21 . Valve  21 , in one position, directs water directly from tank  12  to pump  18 ; in its other position, it connects pump  18  with an input line (suction)  27  including a valve  36  for drawing water from an outside source which could be a lake, hydrant, swimming pool or a water truck. Fire fighting water from whatever source is pumped past a check valve  68  to a differential pressure valve  17 , which corresponds to the differential pressure valve of U.S. Pat. No. 5,009,244 referred to above and which is incorporated by reference and attached to this application. Differential pressure valve  17  maintains a pre-set ratio of foam concentrate to water supplied despite wide variations in flow rate of the mixture. 
   Foam is supplied from a bladder tank  42  which incorporates a flexible bladder  44  containing a Class A foam concentrate, such as the agents sold under the trademark Sylvex of the Ansul Company of Marionette, Wis. Bladder  44  is contained within tank  42  such that it is surrounded by water, which is connected to tank  12  through a water conduit  46  from a three-way selector valve  31  in line with differential pressure valve  17 . The three-way selector valve  31  and metering valve  32 , both of which are described in detail in U.S. Pat. No. 5,009,244, are controlled by means of controls on a selector panel  30  forming part of control panel  11  discussed below. Also connected to three-way selector valve  31  through a conduit  39  is a refill pump  33  which supplies foam concentrate from a source  55  to bladder tank  42 . 
   Water/Foam Supply 
     FIG. 3  is an enlarged schematic drawing of that portion of  FIG. 2  including the water and foam supply system, the differential pressure valve  17 , the three-way selector valve  31 , and the metering valve  32 . Water under pressure from water pump  18  is supplied through check valve  68  to the differential pressure valve  17  where it is mixed with foam concentrate and discharged into conduit  41 . 
   Foam concentrate in bladder tank  42  is supplied through a line  48  to the three-way selector valve  31 . This valve  31  includes a manual selector for selecting one of three positions which are “foam”, “refill” and “off”. Water under pressure from water pump  18  is supplied through the differential pressure valve  17 , conduit  50 , three-way selector valve  31 , and from there via line  46  to the tank  42  where it exerts pressure against the outside of bladder  44 , forcing foam concentrate into three-way selector valve  31  via line  48  and to metering valve  32 . During operation when foam concentrate is required, it flows through the three-way selector valve to the metering valve  32  which is graduated to supply the desired percentage of foam concentrate to water, such as 0.2% to 1%. 
   Differential pressure valve  17 , which is best shown and described in  FIGS. 9–12  of U.S. Pat. No. 5,009,244, incorporated by reference herein and includes a pressure responsive internal plate and piston arrangement which senses the differential pressure between the high pressure at the inlet side of valve  17  and the lower pressure at the outlet side. This sensed differential pressure across valve  17  controls the proportioning of foam concentrate to water irrespective of the rate of water flow through valve  17 . 
   When a water/foam concentrate mixture is desired, metering valve  32  is set to provide the desired ratio of foam concentrate to water. Differential pressure valve  17  responds to water pressure from pump  18  via three-way selector valve  31  to vary the water pressure through conduit  46  against the outside of bladder  44 . This causes foam agent to flow through a line  48  to the three-way selector valve  31  on selector panel  30  discussed above. Foam agent in the selected proportion to water is metered in metering valve  32  which is adjusted to select precisely the desired proportion of foam concentrate to water irrespective of the volume of water flowing through differential pressure valve  17 . Metering or proportioning valve  32  is shown and described in  FIGS. 6–8  of U.S. Pat. No. 5,009,244 incorporated herein by reference. Foam concentrate in the selected proportion is supplied from metering valve  32  through a conduit  51  to differential pressure valve  17  where it is mixed with water. If only a foam/water mixture is desired, this mixture is supplied from differential pressure valve  17  through a conduit  41  of  FIG. 2  to a water/foam solution port on the control panel  11  of  FIG. 1  controlled by two-way valve  40  of  FIG. 2 . 
   Water Only Supply 
   If no foam is desired, metering valve  32  is closed and water is supplied from pump  18  through differential pressure valve  17  to conduit  41 . This conduit is connected to a two-way valve  40  on the face of the control panel  11 . 
   Compressed Air/Foam Supply 
   When a compressed air/foam mixture is desired, valve  40  of  FIG. 2  is closed and water/foam concentrate is supplied from the differential pressure valve  17  through a line  53  to a foam selector metering valve  58  (FSMV). This valve includes a plurality of orifices of different sizes, any one of which may be selected for controlling the volume of water/foam concentrate, which is mixed with the air supply. The foam selector metering valve  58  may have, for example, flow settings of 10 GPM (gallons per minute), 20 GPM, 40 GPM, and 80 GPM. More or fewer orifices and different orifice sizes may be chosen. The selected flow is then supplied to an air injection venturi  84 . 
   The foam selector metering valve  58  is shown in  FIGS. 4 ,  5 ,  6 , and  7 , and includes a body  90 , a shaft  92 , a disk  94  containing a plurality of orifices  94 A,  94 B,  94 C,  94 D,  94 E, and  94 F., and a cover  96 . The shaft  92 , which is supported at one end in body  90 , and at the other end in cover  96 , carries disk  94 , which is secured to shaft  92  by means of a pin  98 , which seats in a slot  100  in disk  94 . A knob or handle  58   a  on the outside of valve  58  (See  FIG. 7 ) turns the shaft  92 , which may be turned to align any of the several orifices shown between inlet passage  102  and outlet passage  104 . 
     FIG. 5  is a rear elevational view of disk  94  showing its several orifices  94 A–F. Slot  100  is shown in dashed lines indicating that it is not visible in this view. 
     FIG. 6  is a vertical sectional view through foam selector metering valve  58 . In this view, shaft  92  is shown secured to disk  94  such that, by rotating disk  94 , any of its several orifices may be aligned between inlet passage  102  and outlet passage  104 . A pin  106  is shown urged into a detent  108  by a spring  110 . There are several such detents, one aligned with each orifice to hold disk  94  in the designed selected position. 
     FIG. 7  is a perspective view of the assembled foam selector metering valve  58 . Visible in this view are the body  90 , the cover  96 , a knob  58   a  for turning shaft  92 , and outlet passage  104 . From the foregoing, it will be clear that by turning knob  58   a  to any of several positions identified by feeling pin  106  drop into a detent, a desired orifice in disk  94  can be aligned with inlet passage  102  and outlet passage  104 . Particular orifices identified as to flow rates may be identified by aligning an arrow on knob  58   a  with marked positions on the control panel  11 , discussed below. 
   Air Metering Valve 
   As shown in  FIG. 2 , compressed air from compressor  52  is supplied over line  80  past a cut-off valve  82  to an air metering valve  54 . The output of the air metering valve  54  is supplied to air injection venturi  84  where it is mixed with the water/foam concentrate from foam selector metering valve  58  and the compressed air/foam mixture is supplied through a conduit  60  and a two-way valve  38  for discharge as the output of a compressed air foam system (CAFS) for fire fighting. 
   Valve  54 , as best seen in  FIGS. 8 and 9 , includes a plurality of orifices sized to supply air at, for example, 25 cubic feet per minute, 35 cubic feet per minute, or 50 cubic feet per minute at the known pressure. The air metering valve  54  is very similar to valve  58 .  FIG. 8  is a vertical sectional view through air metering valve  54  and includes a cover  120 , a body  112 , a shaft  114 , and a disk  116  containing a plurality of orifices of differing sizes, each corresponding to a specific volume of air supplied at a known pressure from the compressor  52  of  FIG. 2 . 
   Cover  120  contains an inlet port  122  and body  112  contains an outlet port  124 . Disk  116  contains a detent  126  for each orifice position and is held in a selected radial position by means of a pin  128  urged into detent  126  by a spring  130 . A knob, unshown but represented by the double-ended arrow in  FIG. 8  is similar to knob  58   a  or a lever may be used to turn shaft  114  to align a desired orifice with inlet passage  122  and outlet passage  124  to provide the desired volume of compressed air. 
     FIG. 9  is a cross-sectional view taken along line  9 — 9  of  FIG. 8 . Body  112  is shown containing disk  116  supported on shaft  114 . Disk  116  is shown with four orifices and four detents  126 , one of which is radially aligned with each orifice. Shown in dotted outline because it is on the opposite face of disk  116  is a pin  132  which sits in a recessed slot  134 . Pin  132  drives disk  116  radially when shaft  114  is rotated. 
   Air Injection Venturi 
     FIG. 10  is a vertical cross-sectional view through the air injection venturi  84 . This unit provides two functions: it includes a venturi for injecting air into the water/foam solution, and a spring-loaded check valve, which blocks water/foam flow until it reaches sufficient pressure to mix properly with the air. A poppet valve  136  in a housing  135  is urged against its seat  138  by means of a spring  140 . An inlet passage  142  connects with a conduit  144  from the foam selector metering valve  58  ( FIG. 2 ). The water/foam solution crossing poppet valve  136  flows through a venturi  137 , which includes a plurality of ports  145  at its throat which connect to air conduit  56  of  FIG. 2 . By creating a low pressure at the venturi throat, air is pulled into the stream of water/foam solution where it is combined to provide the desired mixture. The venturi outlet connects to conduit  60 . 
     FIG. 11  is a cross-sectional view taken along line  11 — 11  of  FIG. 10 . Compressed air from conduit  56  is supplied to an inlet port  150  where it enters a toroidal manifold  152  formed in venturi  137 . Connected to manifold  152  are a plurality of passageways  154  leading to ports  145 . 
   With both air and water pressure controlled and with the precisely sized orifices in both foam selector metering valve  58  and air metering valve  54 , the ratio of water/foam to air remains fixed. There is no need for an operator to balance air and water/foam outputs with flow meters. 
   Air Only Supply 
   The system  10  can supply compressed air only from compressor  52  of  FIG. 2  in the desired quantity as provided from the air metering valve  54 . In this mode, engine E 1  is shut off or declutched from pump  18 , leaving no water pressure at foam selector metering valve  58 . Air under pressure from air metering valve  54  flows through conduit  56 , check valve  69 , air injection venturi  84 , conduit  60 , and valve  38 . 
   Compressor Cooling 
   The preferred air compressor  52  is of the oil flooded rotary screw type supplying air at a minimum of 50 cubic feet per minute of 125 psi at maximum engine RPM. The compressor  52  is driven by a toothed belt drive from the engine E 2  crankshaft. Water flows through the heat exchanger  72  of  FIG. 2  whenever the water pump is operating. The air compressor cooling system incorporates a thermostat that maintains the system oil temperature within a 168 to 225 degree range and is capable of maintaining recommended operating temperatures throughout the full operational range in ambient temperatures up to 115 degrees. 
   Unheated water from water pump  18  is supplied through a pipe  74  to a shell and tube heat exchanger  72  (HE) in  FIG. 2  of all brass and copper construction. A pipe  75  carries cool oil to the lubrication system of compressor  52  where it is exposed to heat, warming the oil in the compressor  52 . The resulting heated oil then flows through a conduit  76  back to the heat exchanger  72  where heat is transferred to the unheated water from pipe  74 . The heated water flows from heat exchanger  72  through a pipe  78  to tank  12 . 
   The compressor  52  is controlled by a pneumatic modulating inlet valve (not shown) mounted to the air end inlet. This controller senses air pressure and controls the air delivery of the air end while maintaining constant pressure. 
   In  FIG. 12  is shown the control panel  11  of the universal fire fighting system  10 . All of the controls necessary for the normal operation in compressed air foam fire fighting are present including several gages and controls for routine monitoring and maintenance of the engines. Essential water, water/foam, and air controls shown have been described above. 
   Near the upper left-hand corner of the panel  11 , there is a key operated ON/OFF switch SW 1 , a throttle T 1 , and a choke control C 1 , for an engine E 1  of  FIG. 2 , which drives water pump  18 . Part of engine E 1  may be seen through the cooling grid opening  15 . The water pump engine E 1  is an internal combustion engine, preferably a 18 horsepower air cooled Briggs &amp; Stratton Vanguard, 2 cylinder, 4-cycle gasoline engine, which includes an alternator and a 12 volt electric starter operated by key switch SW 1 . 
   Shown near the upper right hand corner of the panel is a throttle control T 2 , a choke C 2 , as well as an ON/OFF key switch SW 2  for air compressor engine E 2  partly visible through grill  16 . The air compressor motor E 2  is conveniently located on a rear platform above the level of the hose fittings and wobble pump described below. 
   Upper center on the control panel are two gauges, air pressure gauge  20  and oil pressure gauge  22  for the compressor  52 . Below these two operational gauges are Hobbs meters  24  and  25 , which record running time for the two engines, E 1  and E 2 . 
   Two other key controls are present on the control panel  11 . They are the sub-panel  30 , which includes controls for the metering valve  32  of  FIG. 2  and of U.S. Pat. No. 5,009,244. The panel  30  includes the three-way selector valve  31  for foam proportioning with settings between 0.02% and 1%. The three-way selector valve corresponding to the selector valve of the foregoing U.S. Pat. No. 5,009,244 appears on panel  30  as selector  32 , which is movable to settings of Refill, Foam, and OFF. The next major control is a three-position turn handle for controlling the air pressure in air metering valve  54  located at the lower left immediately adjacent to the grid opening  15 . 
   A wobble pump  34  and primer control  35  are located at the lower right-hand area of the control panel for priming the water pump  18  before commencing operations. 
   The control panel  11  has all of the water input and output lines and each includes one of the half-inch valves controlled by quarter-turn handles, all of which are shown in  FIG. 2  in the “OFF” position. The four lines are water input line  27  controlled by valve  36  (suction), air foam discharge conduit  60  controlled by valve  38 , water/water foam discharge conduit  41  controlled by valve  40 , and water drain  43  controlled by valve  45 . 
   The system is intended for primary operation with a local water tank, such as a 200-gallon tank  12 , loaded on or near the same skid for the system, or a larger tank up to 1000 gallons, which may be transported with the system. Whenever the system is intended to be used with another source of water, such as a hydrant line or by using the pump of the system to pull water from a stream or other source, the hydrant or other source is connected to the input line  27  and valve  21  is moved to its alternate position. 
   Also part of control panel  11  is the foam selector metering valve  58  which includes a valve or disc movable to one of four positions to control the volume of output of water or water/foam mixture supplied from the system  10 . The disc may be movable to select, e.g., 10, 20, 40, or 80 gallons per minute of flow supplied to output conduit  60 . As shown in  FIG. 2 , branching from output conduit  60  is a separate conduit  62 , connected to the hose reel  14  for supplying power to reel the hose in, as required. System drain  35  appears in  FIG. 12  on panel  11  at the lower right. Certain minor features, such as individual drains for draining the tank  42  and the pump  48  in freezing weather have not been illustrated. 
   Altogether, the system of this invention is believed to constitute a universal transportable fire fighting system of greater versatility than heretofore available. 
   The above-described embodiments of the present invention are merely descriptive of its principles and are not to be considered limiting. The scope of the present invention instead shall be determined from the scope of the following claims including their equivalents.