Abstract:
A dry chemical closed recovery system for servicing fire extinguishers including first and second tanks, ball valves, and a pressure relief valve. The dry chemical closed recovery system accepts the high-pressure discharge from a dry chemical fire extinguisher and refills the fire extinguisher with dry chemical using low pressure. By manipulating the ball valves, the fire extinguisher can be refilled incrementally or all at once.

Description:
TECHNICAL FIELD OF THE INVENTION 
       [0001]    The present invention is related to a dry chemical closed recovery system for servicing fire extinguishers. 
       BACKGROUND 
       [0002]    A fire extinguisher, or simply an extinguisher, is a portable device that is used to extinguish small fires, generally in emergency situations. Fire extinguishers are a first line of defense against fires in many homes, offices, and other commercial buildings and can be easily operated when the need arises. In many situations, several fire extinguishers may be conspicuously located inside and/or outside of buildings within ready access by persons in an emergency. Some facilities provide fire extinguisher training to persons working in the facility and ensure that everyone knows the location of nearby fire extinguishers. A typical extinguisher includes a pressurized vessel, usually cylindrical, that contains a dischargeable agent to extinguish the fire. 
         [0003]    Many countries have requirements related to the location and servicing of fire extinguishers. For example, in the United States, fire extinguishers are required in all buildings, except homes, and are required to be serviced and inspected by a fire protection service company at a particular frequency. Generally, fire extinguishers are inspected annually, internal maintenance is performed every 3 to 6 years, and hydrostatic testing is done every 5 to 12 years, depending on the type of extinguisher. 
         [0004]    For both internal maintenance and hydrostatic testing, fire extinguishers are emptied of the agent and depressurized. The extinguisher is disassembled, inspected, cleaned, lubricated, and if necessary, hydrostatic testing is performed. Any extinguisher found defective is replaced. Otherwise, the extinguisher is refilled with agent and pressurized. In the case of dry agent (or dry chemical) fire extinguishers, the agent can be re-used if in good condition. The refilled extinguisher is tagged as having maintenance service and put back into service. 
         [0005]    One system used for dry chemical fire extinguisher maintenance utilizes a generally funnel-shaped hopper. A high-pressure hose is attached to a ball valve on the side of the hopper, near its top. The top of the hopper is fitted with a perforated lid having a filter and an air inlet is located near the bottom of the hopper. The bottom of the hopper tapers to a discharge port that is sized to attach to a tube, which in turn is attached to a manifold. The manifold is a rubber stopper sized to fit the top of the fire extinguisher and has two ports. One port is attached to the tube and the other port is attached to a vacuum source. 
         [0006]    In operation, the discharge nozzle of a fire extinguisher is attached to the free end of the high-pressure hose. The ball valve is opened and the fire extinguisher is discharged into the hopper. The perforated lid allows the pressurized gas to escape while retaining the dry chemical in the hopper. Once all the chemical is discharged, the fire extinguisher is removed for inspection and/or testing. 
         [0007]    To refill, the manifold is attached to the top of the fire extinguisher. A vacuum source is started and as air is pulled through the hopper, the dry chemical is pulled into the fire extinguisher. The air inlet may be opened intermittently to “fluff” the chemical as needed and to assist the flow of the chemical from the hopper. Once the fire extinguisher is filled with the proper amount of dry chemical, the vacuum is removed and the fire extinguisher is pressurized. 
         [0008]    This system has several drawbacks, however. Vacuum sources for refilling and gas sources for fluffing the dry chemical are large, heavy, and noisy. This means that fire extinguishers requiring service must be brought to a maintenance station, such as a facility or mobile vehicle, e.g., a van or truck that houses the maintenance system. A great deal of time is spent by the technician moving fire extinguishers from their installed location to the maintenance station and back to the installed location. To save time, some technicians may bring several fire extinguishers to the maintenance station and empty them into the refill system. However, the potential for cross-contamination of dry chemicals is greatly increased by doing so. 
         [0009]    Additionally, because the dry chemical is discharged into the hopper at high pressure and velocity, the dry chemical can be pushed through the filter in the perforated lid into the atmosphere and can cause it to clog. Furthermore, the open discharge port at the bottom of the hopper can allow the dry chemical to be blown through the tube and attached manifold into the atmosphere, where it may be breathed by the technician. 
         [0010]    During refill, dry chemical may become clogged due to being pulled by vacuum. In addition, dry chemical may also be pulled into the vacuum source, causing fouling and/or failure of the vacuum. 
       SUMMARY 
       [0011]    Embodiments of the present invention relate to a closed recovery system that includes a first tank having a first inlet and a first outlet. The closed recovery system also includes a second tank having a second inlet and a second outlet and the second inlet is coupled to the first outlet. A first ball valve coupled to the first inlet, and a second ball valve is between the first tank and the second tank and coupled to the first outlet and the second inlet. A third ball valve is coupled to the second outlet, and a pressure relief valve is coupled to a third outlet. 
         [0012]    In other, more detailed embodiments of the invention, the closed recovery system further includes a filter manifold having a third inlet and a fourth outlet, the third inlet coupled to the third ball valve. In other, more detailed embodiments of the invention, the filter manifold is configured to couple to a fire extinguisher. In still other, more detailed embodiments of the invention, the pressure relief valve opens at a predetermined pressure. In yet other, more detailed embodiments of the invention, the predetermined pressure is approximately 5-10 psi. 
         [0013]    In other, more detailed embodiments of the invention, the closed recovery system includes a high-pressure hose having a first end and a second end. The first end of the high-pressure hose is coupled to the first ball valve and the second end coupled a quick disconnect fitting. In still other, more detailed embodiments of the invention, at least a side of the first tank slopes toward the first outlet or a side of the second tank slopes toward the second outlet. 
         [0014]    In still other, more detailed embodiments of the invention, the closed recovery system includes a mobile cart wherein at least one of the first tank and second tank is mounted to the mobile cart. 
         [0015]    The present invention also relates to a method of using a closed recovery system, the method including steps of opening a first ball valve coupled to an inlet of a first tank, closing a second ball valve coupled to an outlet of a second tank, discharging dry chemical from a fire extinguisher through the inlet of the first tank until the fire extinguisher is fully discharged, and venting pressure in excess of approximately 5-10 psi through a relief valve coupled to the first tank. After discharging the fire extinguisher, closing the first ball valve. The method also includes steps of opening a third ball valve between an outlet of the first tank and an inlet of the second tank to allow the dry chemical to flow from the first tank to the second tank, closing the third ball valve, and opening the second ball valve to allow the dry chemical to flow through the outlet of the second tank. After the dry chemical in the second tank is discharged, closing the second ball valve, and reopening the third ball valve to allow dry chemical remaining in the first tank to flow to the second tank. The steps of opening and closing the second ball valve to empty the second tank and opening and closing the third ball valve to refill the second tank can be repeated until no dry chemical remains in the closed recovery system. 
         [0016]    In other, more detailed embodiments of the invention, the step of opening the third ball valve between the outlet of the first tank and the inlet of the second tank to allow the dry chemical to flow from the first tank to the second tank is before the step of discharging the dry chemical from a fire extinguisher through the inlet of the first tank until the fire extinguisher is fully discharged. In other, more detailed embodiments of the invention, the dry chemical flows through the outlet of the second tank into a filter manifold and the filter manifold is coupled to a discharged fire extinguisher. In yet other, more detailed embodiments of the invention, the discharged fire extinguisher is the fire extinguisher that was discharged through the inlet of the first tank. 
         [0017]    The present invention also relates to a method of using a closed recovery system, embodiments of the method including opening a first ball valve coupled to an inlet of a first tank, closing a second ball valve coupled to an outlet of a second tank, discharging dry chemical from a fire extinguisher through the inlet of the first tank until the fire extinguisher is fully discharged, venting pressure in excess of approximately 5-10 psi through a relief valve coupled to the first tank, after discharging the fire extinguisher, closing the first ball valve, and opening the second ball valve to allow the dry chemical to flow through the outlet of the second tank. 
         [0018]    Other features of the invention should become apparent to those skilled in the art from the following description of the preferred embodiment(s) taken in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of the invention, the invention not being limited to any particular preferred embodiment(s) disclosed. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0019]    These and other features, aspects, and advantages of the present invention will become better understood with reference to the following description, appended claims, and accompanying drawings, where: 
           [0020]      FIG. 1 a    is a front elevational view of a closed recovery system of a first embodiment according to the present invention. 
           [0021]      FIG. 1 b    is a partial front elevational view of an alternate embodiment of the refill port of  FIG. 1   a.    
           [0022]      FIGS. 2 a  and 2 b    are cross-sectional views of connections in the closed recovery system of  FIG. 1   a.    
           [0023]      FIG. 3  is a front elevational view of a closed recovery system of a second embodiment according to the present invention. 
           [0024]      FIG. 4  is front elevational view of an alternative embodiment of the first tank according the present invention. 
           [0025]      FIG. 5  is front elevational view of an alternative embodiment of the second tank according the present invention. 
           [0026]      FIG. 6  is a flowchart schematically depicting one method of using the closed recovery system of  FIG. 1 a    according to the present invention. 
           [0027]      FIG. 7  is a partial flowchart schematically depicting a second method of using the closed recovery system of  FIG. 1 a    according to the present invention. 
           [0028]      FIG. 8  is a partial flowchart schematically depicting a third method of using the closed recovery system of  FIG. 1 a    according to the present invention. 
           [0029]      FIG. 9  is a front elevational view of a closed recovery system of a third embodiment according to the present invention. 
       
    
    
       [0030]    Unless otherwise indicated, the illustrations in the above figures are not necessarily drawn to scale. 
       DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0031]    All of the features disclosed in the specification, including the claims, abstract, and drawings, and all of the steps in any method or process disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive. Each feature disclosed in the specification, including the claims, abstract, and drawings, can be replaced by alternative features serving the same, equivalent, or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features. 
         [0032]    A first embodiment of a closed recovery system  100  of the present invention is shown in  FIG. 1 a   . The recovery system includes a first tank  110  and a second tank  120  coupled together. 
         [0033]    First tank  110  is generally funnel-shaped and includes sloped sides  112 . The sloped sides  112  allow gravity and pressure within first tank  110 , as described below, to direct dry chemical  102  toward an opening  114  leading to second tank  120 . First tank  110  also includes a lid  116 , or cover, located along the top edge  118  of first tank  110 . The lid  116  can be permanently attached to top edge  118 , for example by welding the lid  116  to the top edge, or removably attached, for example by a releasable clamp (not shown). If lid  116  is removable, a gasket may be required to maintain pressure within first tank  110 . In some embodiments, first tank  110  can further include an optional clear window  119  enabling a user of closed recovery system  100  to see into first tank  110 . 
         [0034]    The lid  116  has two openings. First opening  104  is coupled to a pressure gauge/pressure relief valve  122 , and second opening  106  is coupled to the first end  123  of a high-pressure hose  124 . The other end  125  of the high-pressure hose  124  is coupled to a first ball valve  130  that can close the end  125  of the high-pressure hose  124 . Ball valve  130  is coupled to a quick disconnect fitting  126  that is configured to attach to a fire extinguisher nozzle and can be used to isolate the fire extinguisher from the high-pressure hose  124 . A second ball valve  132  is coupled to the first end  123  of the high-pressure hose  124  near the lid  116  and can be used to isolate the high-pressure hose  124  from the first tank  110 . A third ball valve  134  is coupled between bottom  144  of the first tank  110  and the top  146  of the second tank  120  and can be used to isolate the first tank  110  from the second tank  120 . 
         [0035]    The second tank  120  has sides  128  sloping outwardly from the top  146  and sides  140  sloping inwardly toward the bottom  148 . Between the outwardly sloping sides  128  and the inwardly sloping sides  140 , the second tank  120  may have generally vertical sides  142 . Inwardly sloping sides  140  allow gravity and pressure within second tank  120 , as described below, to direct dry chemical  102  toward an opening  150 . A fourth ball valve  136  is located at the opening  150  at the bottom of the second tank  120  and can be used to isolate the second tank  120  from refill port  152 . In some embodiments, second tank  120  can further include an optional clear window  129  enabling a user of closed recovery system  100  to see into second tank  120 . 
         [0036]    Refill port  152  can include a filter manifold  154 . As seen in  FIG. 1 a   , filter manifold  154  is coupled to the fourth ball valve  136 . The filter manifold  154  includes vents  160  that are covered with filter material  172  to allow gas to escape, but not dry chemical  102  dust, when the dry chemical  102  is reintroduced into the fire extinguisher. The end  157  of the filter manifold  154  can be threaded to accept the threads of an empty fire extinguisher or the threads of an optional metal or plastic adapter  158  that threads onto an empty fire extinguisher. As shown in  FIG. 1 b   , in alternative embodiments, the filter manifold  154  can be coupled between fourth ball valve  136  and a fill tube or hose  156 . Optionally, a fifth ball valve  138  can be at the end of the fill tube or hose  156  opposite the filter manifold  154 . An adapter  158  can be coupled to the end of the fill tube or hose  156  or fifth ball valve  138  (if present) and is used to couple an empty fire extinguisher to the closed recovery system  100 . The adapter  158  may be threaded or may be pressure-fitted for coupling with the fire extinguisher. 
         [0037]    Referring back to  FIG. 1 a   , quick disconnect fitting  126  is a standard fitting used to quickly and easily connect hoses or tubing to another hose or to various vessels. Fittings  126  include two parts, one of which fits into the other in a male/female fashion to lock into place. Uncoupling is accomplished by lifting a collar, lever, or a small twisting motion. Useful fittings  126  are inert to the dry chemical  102  and are typically made of metal or plastic, for example, brass, chrome-plated brass, nickel plated brass, stainless steel, acetal, polypropylene, or acrylonitrile butadiene styrene (ABS). 
         [0038]    High-pressure hose  124  is a standard hose known in the industry. Hoses can be made of rubber, plastic, or composites thereof, and can be layered or sheathed. Fibrous material or metal mesh can be encased within the hose  124  for additional strength. High-pressure hose  124  can be opaque, translucent, or transparent. Translucent and transparent hoses permit the user to see the flow of dry chemical  102  during discharge. The ability to see the flow of dry chemical  102  can be useful to determine when the fire extinguisher is fully discharged. The inner diameter of high-pressure hose  124  may vary, with typical diameters ranging from about ⅛ inches to ⅜ inches and may be ½ inches or more in diameter. 
         [0039]    Pressure gauge/relief valve  122  is coupled to first tank  110 .  FIG. 1 a    shows the pressure gauge/relief valve coupled to the top of first tank  110  to reduce contamination with dry chemical  102 , however, it may be coupled to closed recovery system  100  at any convenient location. Pressure gauge/relief valve  122  is made of metal, for example, brass, chrome-plated brass, nickel plated brass, stainless steel, or other metal that is inert to dry chemical  102 . The relief valve portion is configured to allow a maximum of about 5 psi to about 10 psi of pressure to remain in first tank  110 , or first tank  110  and second tank  120  if third ball valve  134  is open, and may be protected from dry chemical  102  by a filter. In some embodiments, the relief valve portion can be configured to allow a maximum of 25 psi to remain in the tank(s) so that neither first tank  110  nor second tank  120  is required to be hydrotested. Additionally,  FIG. 1 a    shows the pressure gauge/relief valve  110  as a single element, however, a separate pressure gauge and relief valve can be used. 
         [0040]    First tank  110  and second tank  120  can be made of the same material or can be different materials. Suitable materials include metals, such as stainless steel, carbon steel, iron, carbon fiber, plastic, and other materials that are not affected or corroded by the dry chemical  102 . The thickness of materials is such that the tanks  110  and  120  are capable of holding about 5 psi to about 10 psi internal pressure, or as high as 25 psi. 
         [0041]    The size of first tank  110  can vary, depending on the size of the fire extinguisher being serviced. In some embodiments, first tank  110  is sized to contain approximately 4× the volume of dry chemical  102  in a fire extinguisher. In other embodiments, first tank  110  is sized to contain approximately 20 pounds of dry chemical  102 , and while in other embodiments, first tank  110  is sized to contain approximately 2-3 gallons of dry chemical  102 . The size of second tank  120  can also vary. In some embodiments, second tank  120  is sized to contain ½ the volume of first tank  110 . In other embodiments, second tank  120  is sized to contain approximately 10 pounds of dry chemical  102 , and while in other embodiments, second tank  120  is sized to contain approximately 1-1.5 gallons of dry chemical  102 . In yet other embodiments, second tank  120  is sized to hold less dry chemical  102  than one fire extinguisher. Thus, first tank  110  can be sized to hold dry chemical  102  from at least one fire extinguisher, and second tank  120  can be sized to hold dry chemical  102  from less than one fire extinguisher. In this manner, if a fire extinguisher is fully discharged into closed recovery system  100 , second tank  120  may be filled with dry chemical  102  and first tank  110  may be at least partially filled. Additionally, since the pressure in first tank  110  and second tank  120  is limited by pressure gauge/relief valve  110  to less than about 25 psi, hydrostatic testing of the tanks is not needed. 
         [0042]    First, second, third, fourth, and optional fifth ball valves  130 ,  132 ,  134 ,  136 ,  138  are standard ¼ turn ball valves that allow material to flow straight through. All the ball valves can be the same type of valve, or they may be different, for example, first and second ball valves  130 ,  132  can be rated for higher pressures than third, fourth, and optional fifth ball valves  134 ,  136 ,  138 . In one embodiment, first and second ball valves  130 ,  132  can be rated at 195 psi and third, fourth, and optional fifth ball valves  134 ,  136 ,  138  can be rated at 10 psi. Ball valves  130 ,  132 ,  134 ,  136 ,  138  can be made of metal or plastic, for example, brass, chrome-plated brass, nickel plated brass, bronze, stainless steel, carbon steel, ceramics, acetal, polypropylene, acrylonitrile butadiene styrene (ABS), polyvinyl chloride (PVC), and chlorinated polyvinyl chloride (CPVC). Materials that form the ball valves  130 ,  132 ,  134 ,  136 ,  138  should be inert to the dry chemical  102 . 
         [0043]    Quick release fitting  126  and ball valves  130 ,  132 ,  134 ,  136 ,  138  are coupled to the closed recovery system  100  by threaded connections, compression fittings, hose barbs, or other type of connection, for example. An example connection  170   a  shown in  FIG. 2 a    includes a male-threaded upstream portion  162   a  and a female-threaded downstream portion  164   a . The arrow  166  indicates direction of flow. A ledge  168  is formed in the connection  170   a  due to the slightly different inner diameters of portions  162   a  and  164   a . Gas and dry chemical  102  are able to pass by the ledge  168  without the dry chemical  102  becoming lodged. An alternative example connection  170   b  shown in  FIG. 2 b    includes a female-threaded upstream portion  162   b  and a male-threaded downstream portion  164   b . In this configuration, dry chemical  102  may remain on the ledge  168  after flow has stopped. Any dry chemical  102  remaining on the ledge  168  may be dislodged by the user, for example, by slightly shaking or jostling the connection or entire system  100 , to avoid possible contamination with subsequent dry chemicals used. In one embodiment, connections include male upstream portions and female downstream portions. 
         [0044]    Filter manifold  154  can be made of the same material as first tank  110  and second tank  120 , such as metal or plastic, for example, stainless steel, carbon steel, and iron, carbon fiber, acetal, polypropylene, ABS, PVC, and CPVC. The thickness of the filter manifold  158  may be less than the thickness of first and second tanks  110 ,  120  since vents  160  allow reduction of pressure to ambient pressure. Filter material  172  is made of any material suitable of preventing dry chemical  102  from escaping, such as, tightly woven cloth or fabric, non-woven fibers, ceramic, or other material that allows only gas to escape. The same filter material can be used to protect pressure gauge/relief valve  110  as described previously. Filter material  172  can be easily changed to accommodate various types of dry chemical  102  or cleaned. Some filter materials  172  may be suitable for more than one type of dry chemical  102 . 
         [0045]    Turning now to  FIG. 3 , a second embodiment of a closed recovery system  200  according to the present invention is shown. Closed recovery system  200  includes closed recovery system  100  mounted onto a mobile cart  280 , such as a hand truck or wagon, for example. 
         [0046]    Mobile cart  280  includes handles  282  that a user can grasp and use to maneuver the cart. The mobile cart  280  can have two or more wheels  284  which are in contact with the ground so that the mobile cart  280  can be easily moved from one location to another. If the mobile cart  280  has two wheels  284 , the cart can also have a support  294  that holds the cart upright yet allows the cart to be tilted onto the wheels  284  when being moved. 
         [0047]    Closed recovery system  100  can be coupled to the mobile cart  280  with a clamp or bracket  292 . The clamp or bracket  292  can be a round ring with a diameter less that the diameter of the first tank  110  such that closed recovery system  100  is supported by the clamp or bracket  292 . In some embodiments, closed recovery system  100  can be permanently or semi-permanently coupled to the clamp or bracket  292 , for example, bolts can be used to couple the clamp or bracket to the first tank  110 . 
         [0048]    Closed recovery system  200  can also include a gas cylinder  288  and a weighing scale  290  that rest on a platform  286 . The gas cylinder  288  can be used to recharge system  100  if there is insufficient pressure to cause dry chemical  102  to flow when refilling a fire extinguisher. The gas cylinder  288  is also used to pressurize a refilled fire extinguisher before placing it back into service. The weighing scale  290  is used to weigh the fire extinguisher to determine when sufficient dry chemical  102  has been added to a fire extinguisher being refilled. 
         [0049]    Turning now to  FIG. 9 , a third embodiment of a closed recovery system  600  according to the present invention is shown. Closed recovery system  600  includes first tank  610  and second tank  620 . First tank  610  and second tank  620  are similar in many respects to first tank  110  and second tank  120 . High-pressure hose  624  is coupled to first tank  610  and can also be coupled to a fire extinguisher. Pressure gauge/relief valve  622  is attached to the top of first tank  610 . Ball valve  632  is coupled between first tank  610  and high-pressure hose  624 . Ball valve  634  is coupled between first tank  610  and second tank  620 , and ball valve  636  is coupled to the bottom of second tank  620 . Ball valves  632 ,  634 , and  636  are similar to ball valves  132 ,  134 , and  136 , respectively. 
         [0050]    Closed recovery system  600  also includes a hand truck  680 . Hand truck  680  includes supports  696  to which clamps  692  and  694  are coupled. Clamps  692  and  694  can be generally circular and couple first tank  610  and second tank  620 , respectively, to supports  696 . The tanks  610 ,  620  may be held in place by gravity, or clamps  692 ,  694  may tighten onto tanks  610 ,  620 . Alternatively, tanks  610 ,  620  may be permanently or removably coupled to clamps  692 ,  694  by nuts and bolts, screws, rivets, or welds, for example. 
         [0051]    Hand truck  680  includes handles  682  at the top ends of supports  696 . Handles  682  can be rubberized grips slipped over the ends of supports  696 . Furthermore, supports  696  may be bent near the ends to form handles that are more ergonomical. Tray  686  is coupled to the bottom ends of supports  696 . Tray  686  can be used for carrying a scale, a bottle of compressed gas, or other items the user may require for discharging and recharging a fire extinguisher. Hand truck  680  also includes at least a pair of wheels  684  for moving closed recovery system  600  easily from one location to another. Wheels  684  can be any size suitable for traversing the terrain from one location to another. Such terrain may include steps, uneven concrete, thick carpeting, etc., for example. 
         [0052]    Supports  696  can be made of metals, metal alloys, plastics, and combinations thereof. Any material capable of supporting the weight being transported can be used. Supports  696  can be solid or hollow. Clamps  692 ,  694  can be made of metals, metal alloys, plastics, and combinations thereof. Any material capable of supporting the weight of the tanks  610 ,  620  and dry chemical  102  can be used. Additionally, clamps  692 ,  694  can be unitary, such as a ring, or can be made of several pieces. For example, clamps  692 ,  694  can be made of two pieces of material that are bolted together. By unbolting clamps  692 ,  694 , tanks  610 ,  620 , respectively, can be easily removed for cleaning or replacement. 
         [0053]    Turning now to  FIG. 4 , in some embodiments of closed recovery system  100 , first tank  110  can include generally vertical sides  113  in addition to sloped sides  112 . Vertical sides  113  can increase the volume of the first tank without increasing the diameter. In this manner, a single mobile cart  280  can be fitted with closed recovery systems  100  that can recharge larger fire extinguishers. 
         [0054]    In some embodiments of closed recovery system  100 , second tank  120  can include outwardly sloping sides  128  and inwardly sloping sides  140 , as shown in  FIG. 5 . 
         [0055]      FIG. 6  is a flowchart of a method of using closed recovery system  100  according to the present invention, shown generally at  300 . At step  310 , a fire extinguisher is attached to quick disconnect fitting  126 . An adapter may be fitted onto the fire extinguisher, if needed, for attachment. At step  320 , first ball valve  130 , second ball valve  132 , and third ball valve  134  are opened to allow dry chemical  102  to flow into the closed recovery system  100 , and fourth ball valve  136  is closed to prevent dry chemical  102  from escaping the closed recovery system  100 . 
         [0056]    At step  330 , the fire extinguisher is fully discharged into the first tank  110  and the second tank  120  of the closed recovery system  100 . Fire extinguishers are generally under high pressure, for example, 195 psi. Discharge of the fire extinguisher into the larger volume of the closed recovery system  100  reduces the pressure. The pressure is further reduced by venting gas through pressure gauge/relief valve  122  to approximately 5-10 psi. 
         [0057]    After the fire extinguisher is fully discharged, at step  340 , first ball valve  130  is closed and the fire extinguisher is disconnected from quick disconnect fitting  126 . Second ball valve  132  may closed after ensuring all dry chemical  102  is emptied from the high-pressure hose  124 , and the high-pressure hose removed. Alternatively, second ball valve  132  may remain open and high-pressure hose  124  remain attached. After removal, the fire extinguisher can be inspected and repaired, if needed. After inspection and repair, the fire extinguisher is ready to be recharged. At step  350 , the fire extinguisher is connected to the filter manifold  154  at the bottom of the closed recovery system  100 . 
         [0058]    At step  360 , fourth ball valve  136  is opened and pressure within the closed recovery system  100 , along with gravity, forces the dry chemical  102  into the fire extinguisher. Pressure is vented through the filter material  172  covering the vents  160  on the filter manifold  154  to ambient pressure. The funnel shape of first tank  110  and second tank  120  help to guide the dry chemical  102  into the fire extinguisher. When all of the dry chemical  102  has been emptied from the closed recovery system  100 , the fire extinguisher can be removed, weighed on scale  290  to assure the proper amount of dry chemical  102  is in the fire extinguisher, and the fire extinguisher re-pressurized using gas cylinder  288 . 
         [0059]    In second method of using closed recovery system  100  according to the present invention, steps  320  and  330  are modified as shown in step  420  in  FIG. 7 . In step  420 , third and fourth ball valves  134 ,  136  are closed, and first and second ball valves  130 ,  132  are opened. The fire extinguisher can then be fully discharged into the first tank  110  of the closed recovery system  100 . The pressure is reduced to approximately 5-10 psi by venting pressurized gas through the pressure gauge/relief valve  122 . After the fire extinguisher is fully discharged, third ball valve  134  is opened. The method continues at step  340  in  FIG. 6 . The second method makes use of a smaller volume of gas pressurized to 5-10 psi. Opening the third ball valve  134  while the first tank  110  is under lower pressure may help to prevent dry chemical  102  from caking in second tank  120 . 
         [0060]    In a third method of using closed recovery system  100  according to the present invention, step  360  is replaced with the steps shown in  FIG. 7 . At step  560 , third ball valve  134  is closed. Fourth ball valve  136  is opened in step  562 , allowing dry chemical  102  in second tank  120  to flow into the fire extinguisher. At step  564 , the user determines if the fire extinguisher is filled. This can be done by closing the fourth ball valve  136  and weighing the fire extinguisher. Alternatively, the user can listen for gas escaping from the filter manifold  154  when the fourth ball valve  136  is opened. If the user determines the fire extinguisher is filled the method ends and the fire extinguisher is re-pressurized. If the fire extinguisher is not filled, the fourth valve  136  is closed in step  566 . At step  568 , the third valve  134  is opened, allowing additional dry chemical to move into the second tank  120 . The method continues at step  560  by again closing the third ball valve  134 . Third and fourth ball valves  134 ,  136  are alternately opened and closed in this manner to slowly fill the fire extinguisher with dry chemical  102 . It should be noted that second tank  120  may be filled or only partially filled if third ball valve  134  is closed before second tank is full. By partially filling second tank  120 , the fire extinguisher can be refilled slower than if second tank  120  were completely filled. By slowly filling the fire extinguisher according to the third method, dry chemical  102  can remain fluffed as it fills the fire extinguisher. 
         [0061]    The foregoing detailed description of the present invention is provided for purposes of illustration, and it is not intended to be exhaustive or to limit the invention to the particular embodiments disclosed. The embodiments may provide different capabilities and benefits, depending on the configuration used to implement the key features of the invention. Accordingly, the scope of the invention is defined only by the following claims.