Patent Publication Number: US-9896833-B2

Title: Flow control system

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     Not Applicable 
     FIELD OF THE INVENTION 
     The disclosure relates to the field of flow control systems and more particularly to a flow control system for detention ponds, surge tanks, reservoirs and other applications wherein upstream fluid levels vary in response to varying rates of inflow. 
     BACKGROUND 
     There are many fluid handling systems wherein the upstream fluid levels or pressures vary and it is desirable to passively control the rate of release with a flow control system which requires no human intervention or external energy source to activate. Examples of these systems include storm water detention ponds, storage reservoirs, holding tanks, surge tanks and the like. In general, these systems receive varying rates of fluid flow, which at times may exceed the desirable release rate or range of release rates as the case may be. When the inflow rate to these systems exceeds the release rate, a volume of fluid is stored and in response, the upstream fluid level rises. Conversely, when the release rate exceeds the inflow rate, the stored volume of fluid is released and the upstream fluid level falls. 
     Historically, the release rate from these type systems has been passively controlled with weirs and orifices, both of which produce flow rates which increase exponentially as the upstream fluid level rises. When inflow rates dramatically exceed the desirable outflow rate, this characteristic often results in a system wherein a large volume of storage is required to control the fluid at or below the level which does not produce a release in excess of the desired rate or range of rates. Since the costs of land acquisition, engineering, construction and transportation associated with creating large volumes of storage can be quite expensive, it is advantageous to design these systems with as little volume as possible. This objective is accomplished when the system design accommodates release at the desired rate for the maximum amount of time, as is depicted in FIG. 3 of U.S. Pat. No. 7,052,206 to Mastromonaco. 
     The prior art is replete with a variety of possible solutions to this design problem. One such example is disclosed in U.S. Pat. No. 7,125,200 to Fulton wherein he describes a flow control device for a holding pond consisting of a buoyant flow control module housing an orifice within an interior chamber that is maintained at a predetermined depth below the water surface. Fluid discharged through the orifice is conveyed to the outlet through a bellow, an accordion like conduit which facilitates vertical motion of the buoyant flow control module. Another such example is disclosed in U.S. Pat. No. 6,997,644 to Fleeger, wherein he describes a floating weir assembly for incorporation into a detention vessel. The floating weir assembly is supported by a buoyant means which maintains the weir opening at a predetermined depth below the water surface. In order to facilitate vertical motion, fluid passing over the weir is conveyed to the outlet by means of a hose which has greater capacity than the discharge produced by the weir. In U.S. Pat. No. 6,474,361 to Poppe a floating weir assembly is described which is ballasted with a flowable medium such as liquid or a solid particulate matter like sand to maintain the submergence of the assembly at predetermined depth below the fluid surface. Similar to Fleeger&#39;s disclosure, the preferred means to convey discharge to the outlet is a flexible hose. In U.S. Pat. No. 7,762,741 to Moody, co-inventor of the present disclosure, a flow control system for incorporation into a detention pond or surge tank is described whereby a moving riser, made buoyant and supported by at least one float is suspended within a stationary riser such that the opening to the moving riser is maintained at a fixed and predetermined depth below the fluid surface. Discharge through and around the moving riser is conveyed to the outlet through the stationary riser. Each of the foregoing examples utilize buoyancy to maintain the opening of a fluid passage at a fixed and predetermined depth below the upstream fluid surface. 
     Other proposed solutions have used buoyancy to effect changes in the area of a fluid passage. One such example is disclosed in U.S. Pat. No. 8,043,026 to Moody, co-inventor of the present disclosure, wherein a flow control system for incorporation into a detention pond or surge tank is described. The flow control system comprises a tapered plunger, suspended from at least one float, and the tapered plunger is located within and at the bottom edge of a vertically oriented tube which is fixed in a stationary position. Fluid from the upstream reservoir enters the tube from the upper end and its flow is restricted at the bottom end. As the upstream fluid level changes, at least one float moves the tapered plunger such that the area of the fluid passage between the inside, bottom edge of the stationary tube and the outside edge of the tapered plunger is reduced when the fluid level rises and conversely, increases as the fluid level falls. In the preferred embodiment, the taper of the plunger is formed such that the change in the area of the fluid passage maintains the flow rate at a constant rate. 
     Other solutions have sought to change the area of the fluid passage by the use of pressure rather than buoyancy. In U.S. Pat. No. 5,887,613 to Steinhardt a flow control system is disclosed whereby fluid pressure acts against a “form-changeable member” with a hollow interior which is connected to a pressure different from the pressure outside of the “form-changeable member”. The “form-changeable member” is biased with a spring against a bracket which supports a gate over the fluid passage. As the fluid level in the upstream reservoir rises, the pressure acting on the “form-changeable member” in turn rises, acting against the spring and reducing the area of the fluid passage. In the preferred embodiment, the bias of the spring and the geometry of the gate are designed such that the flow rate through the fluid passage remains constant as the upstream fluid levels both rise and fall. 
     Although all of these disclosures are passively operated and can theoretically control the rate of fluid release at a constant or nearly constant rate, they all rely on floats, springs and/or flexible conduits operating in conditions wherein the pressure on the outside of the conduit is higher than the pressure inside the conduit. These features have proven to be problematic for a number of reasons. Floats which are hollow can rupture and floats which are solid can absorb water over time which increases their density and reduces their net buoyancy. Springs may suffer from decreasing bias over time due to strain and repeated cyclical motion. Metallic springs can often corrode due to a variety of elemental exposures. Flexible conduits such as bellows and hoses, operating in conditions where the pressure outside of the conduit is greater than the pressure inside of the conduit, may collapse from the effects of excess hydrostatic pressure, often at depths much less than the design depth of the storage reservoir in which they are immersed. 
     Accordingly, there is a need for a flow control system that does not rely on floats, biasing members such as springs, or flexible conduits which are immersed in the fluid reservoir from which the flow control system is intended to control the release. 
     SUMMARY 
     The flow control system of the present invention includes an expanding conduit, an axis of which is vertical, and is fluidly interfaced, through a closed conduit, to an upstream reservoir and the interior of a container which is fluidly interfaced to a downstream drainage system. The distal, upper end of the expanding conduit is capped and at least one fluid passageway, which opens from the interior of the expanding conduit through the distal, capped, upper end of the expanding conduit is provided. If at least one fluid passageway through the distal, capped, upper end of the expanding conduit is oriented horizontally, the fluid passageway has an open area which is smaller than the cross sectional area of the inner dimensions of the expanding conduit. A means to restrain the expanding conduit from lateral motion is also provided and allows for a fluid connection between the interior of the expanding conduit and the interior of the container. When the fluid level in the upstream reservoir is at its initial, minimum, controlled level, the expanding conduit is in a less than fully expanded state, and the lowest point of at least one fluid passageway, which opens from the interior of the expanding conduit, is at the same initial and minimum level. As the upstream reservoir receives inflow and the fluid level rises above the initial, minimum, controlled level, the fluid flows from the reservoir, through the closed conduit, upward through the expanding conduit, out through at least one fluid passageway provided through the distal, capped, upper end of the expanding conduit, where it then passes through the means to restrain the expanding conduit from lateral motion and into the interior of the container, wherein it then flows out to the downstream drainage system which is fluidly interfaced to the container. Further, as the fluid level in the upstream reservoir continues to rise, the fluid pressure in the interior of the expanding conduit rises and, in turn, exerts an upward force on the underside of the distal, capped, upper end of the expanding conduit, and thereby moves the distal, capped, upper end of the expanding conduit, and at least one fluid passageway which opens from the interior of the expanding conduit, upward to a prescribed level which is below the fluid level in the upstream reservoir, and the rate of flow through the flow control system is maintained at the desirable release rate or range of release rates prescribed for the fluid handling system. 
     In one embodiment, a flow control system for integration into a fluid handling system, wherein the upstream fluid level varies, is disclosed including an expanding conduit in the form of a bellows, an axis of which is vertical, and is fluidly interfaced, through a closed conduit, to an upstream reservoir, and the interior of a container which is fluidly interfaced to a downstream drainage system. The distal, upper end of the bellows is capped and at least one fluid passageway, which opens from the interior of the expanding conduit through the distal, capped, upper end of the expanding conduit, is provided. At least one fluid passageway is oriented horizontally and has an open area which is less than the cross sectional area of the inner dimensions of the bellows. 
     The bellows is enclosed by a rigid tube, an axis of which is also vertical, and restrains the bellows from lateral movement. The rigid tube has at least one opening along its axis such that it is fluidly connected to the inside of the container and the downstream drainage system. When the fluid level in the upstream reservoir is at its initial, minimum, controlled level, the bellows is in a less than fully expanded state and at least one passageway through the distal, capped, upper end of the bellows is at a same initial, minimum level. As the upstream reservoir receives inflow and the fluid rises above the initial, minimum, controlled level, the fluid flows from the reservoir, through the closed conduit, upward through the bellows, out through at least one fluid passageway at the distal, capped, upper end of the bellows and into the interior of the rigid tube enclosing the bellows, wherein it flows out through at least one opening along its axis into the interior of the container, wherein it then flows out to the downstream drainage system interfaced to the container. Further, as the fluid level in the upstream reservoir continues to rise, the fluid pressure in the interior of the bellows rises and, in turn, exerts an upward force on the underside of the distal, capped, upper end of the bellows, and moves the distal, capped, upper end of the bellows, and at least one fluid passageway, which opens from the interior of the bellows, upward to a prescribed level which is below the fluid level in the upstream reservoir, and the rate of flow through the flow control system is maintained at the desirable release rate or range of release rates prescribed for the fluid handling system. 
     In another embodiment, a flow control system for integration into a fluid handling system, wherein the upstream fluid level varies, is disclosed including an expanding conduit in the form of a bellows, an axis of which is vertical, and is fluidly interfaced, through a closed conduit, to an upstream reservoir, and the interior of a container which is fluidly interfaced to a downstream drainage system. The distal, upper end of the bellows is capped and at least one fluid passageway, which opens from the interior of the expanding conduit through the distal, capped, upper end of the expanding conduit, is provided. At least one fluid passageway is oriented vertically. The bellows is enclosed by a rigid tube, an axis of which is also vertical, and restrains the bellows from lateral movement. The rigid tube has at least one opening along its axis such that it is fluidly connected to the inside of the container and the downstream drainage system. When the fluid level in the upstream reservoir is at its initial, minimum, controlled level, the bellows is in a less than fully expanded state and the lowest point of at least one fluid passageway through the distal, capped, upper end of the bellows is at a same initial, minimum level. As the upstream reservoir receives inflow and the fluid rises above the initial, minimum, controlled level, the fluid flows from the reservoir, through the closed conduit, upward through the bellows, out through at least one fluid passageway at the distal, capped, upper end of the bellows into the interior of the rigid tube enclosing the bellows, wherein it flows out through the opening along its axis into the interior of the container, wherein it then flows out to the downstream drainage system interfaced to the container. Further, as the fluid level in the upstream reservoir continues to rise, the fluid pressure in the interior of the bellows rises and, in turn, exerts an upward force on the underside of the distal, capped, upper end of the bellows, and moves the distal, capped, upper end of the bellows and at least one fluid passageway which opens from the interior of the bellows, upward to a prescribed level which is below the fluid level in the upstream reservoir, and the rate of flow through the flow control system is maintained at the desirable release rate or range of release rates prescribed for the fluid handling system. 
     In another embodiment, a flow control system for integration into a fluid handling system, wherein the upstream fluid level varies, is disclosed including an expanding conduit in the form of a bellows, an axis of which is vertical, and is fluidly interfaced, through a closed conduit, to an upstream reservoir, and the interior of a container which is fluidly interfaced to a downstream drainage system. The distal, upper end of the bellows is capped and at least one fluid passageway which opens from the interior of the bellows is provided through the distal, capped, upper end of the bellows. At least one fluid passageway intersects the vertical axis of the distal, capped, upper end of the bellows and is provided in the form of a short tube oriented such that its exit into the interior of the container is directed downward. The bellows is enclosed by a rigid tube, an axis of which is also vertical, and restrains the bellows from lateral movement. The rigid tube has at least one slot along the length of its axis. At least one slot along the length of its axis is aligned such that the short tube is guided within the slot and its exit is fluidly connected to the inside of the container and the downstream drainage system. When the fluid level in the upstream reservoir is at its initial, minimum, controlled level, the bellows is in a less than fully expanded state and the lowest point of at least one fluid passageway through the distal, capped, upper end of the bellows, at the point where at least one fluid passageway intersects the distal, capped upper end of the bellows, is at a same initial, minimum level. As the upstream reservoir receives inflow and the fluid rises above the initial, minimum, controlled level, the fluid flows from the reservoir, through the closed conduit, upward through the bellows, out through at least one fluid passageway at the distal capped, upper end of the bellows into the interior of the rigid tube enclosing the bellows, wherein it flows out through the opening along its axis into the interior of the container, wherein it then flows out to the downstream drainage system interfaced to the container. Further, as the fluid level in the upstream reservoir continues to rise, the fluid pressure in the interior of the bellows rises and, in turn, exerts an upward force on the underside of the distal, capped, upper end of the bellows, and moves the distal, capped, upper end of the bellows and at least one fluid passageway which opens from the interior of the bellows, upward to a prescribed level which is below the fluid level in the upstream reservoir, and the rate of flow through the flow control system is maintained at the desirable release rate or range of release rates prescribed for the fluid handling system. 
     To the accomplishment of the above and related objects the present invention may be embodied in the form illustrated in the accompanying drawings. Attention is called to the fact that the drawings are illustrative only. Variations are contemplated as being a part of the present invention, limited only by the scope of the claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention can be best understood by those having ordinary skill in the art by reference to the following detailed description when considered in conjunction with the accompanying drawings in which: 
         FIG. 1  illustrates a schematic of a system of the present invention wherein the fluid level in the upstream reservoir is at its initial, minimum, controlled level; 
         FIG. 2  illustrates a schematic of a system of the present invention wherein the fluid level in the upstream reservoir has risen above its minimum, controlled level; 
         FIG. 3  illustrates a perspective view of the distal, capped, upper end of the expanding conduit of a first embodiment of the present invention; 
         FIG. 3A  illustrates a perspective view of an alternate distal, capped, upper end of the expanding conduit of a first embodiment of the present invention; 
         FIG. 3B  illustrates a perspective view of the distal, capped, upper end of the expanding conduit of a second embodiment of the present invention; 
         FIG. 3C  illustrates a perspective view of the distal, capped, upper end of the expanding conduit of a third embodiment of the present invention; 
         FIG. 4  illustrates a perspective view of the expanding conduit enclosed within a means to prevent lateral movement of a first embodiment of the present invention; 
         FIG. 4A  illustrates a perspective view of the expanding conduit enclosed within an alternate means to prevent lateral movement of the present invention; 
         FIG. 4B  illustrates a perspective view of the expanding conduit of a first embodiment of the present invention enclosed by a second alternate means to prevent lateral movement; 
         FIG. 4C  illustrates a perspective view of the expanding conduit enclosed within a third alternate means to prevent lateral movement of the present invention; 
         FIG. 5  illustrates a schematic of an alternate embodiment of the present invention; 
         FIG. 6  illustrates a schematic of a second alternate embodiment of the present invention; 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION AND PREFERRED EMBODIMENT 
     Reference will now be made in detail to the presently preferred embodiments of the invention, examples of which are illustrated in the accompanying drawings. Throughout the following detailed description, the same reference numerals refer to the same elements in all figures. Throughout the following description, the terms fluid handling system, detention pond, surge tank, holding tank, reservoir, and other applications wherein upstream fluid levels vary, represent any such structure and are equivalent structure for storing a fluid and discharging it at a prescribed, desirable rate or range of rates as the case may be. 
     The flow control system described provides for an initial discharge rate starting as soon as the upstream reservoir reaches a pre-determined, minimum, controlled fluid level. Then, as the fluid level increases, the discharge rate is controlled at a prescribed rate or range of rates until a high-water level is reached, at which level the flow control system provides for an increased discharge rate to reduce the possibility of exceeding the volumetric capacity of upstream reservoir. 
     Prior to more advanced flow control systems, limiting the maximum outflow rates was accomplished by the use of fixed weirs and orifices, flow control systems whereby the discharge was controlled in response to the movement of a float, or the bias of a spring, or flow control systems wherein a flexible conduit is immersed in such a manner that the pressure outside of the flexible conduit is greater than the pressure inside of the flexible conduit. Fixed weirs and orifices can only control the discharge rate within a broad range, determined by the range of the fluid level fluctuation in the upstream reservoir. Flow control systems whereby the discharge rate is controlled in response to the movement of floats can be subject to failure if hollow floats are ruptured. Solid displacement float can also suffer a decrease in their net buoyancy, over time, if the floats are formed from materials which have the propensity to absorb fluid. Flow control systems whereby the discharge rate is controlled in response to the bias from a spring can fail, over time, due to decreasing bias caused by strain and repeated cyclical motion, and metallic springs are vulnerable to the effects of corrosion from a variety of elemental exposures. Flow control systems wherein a flexible conduit is immersed in fluid, such that the pressure outside of the flexible conduit is greater than the pressure inside of the flexible conduit, are known to have a very limited range of depth at which they may operate without subjecting the flexible conduit to pressures at which the flexible conduit will collapse. The present invention solves these and other problems as is evident in the following description. 
     Referring to  FIG. 1 , a schematic view of a system of the present invention will be described. The flow control system  30  is incorporated into a fluid handling system  10  wherein the flow control system  30  receives the flow of fluid  3  from an upstream reservoir  1  and discharges the flow to a downstream drainage system  60 . 
     The flow control system  30  consists of four primary components; a closed conduit  31 , an expanding conduit in the form of a bellows  40  which is restrained from lateral movement, a cap  45 , and a container  20 . The closed conduit  31  is made of plastic, metal, concrete or any other material which is suitable for conveying the fluid  3 , and is connected to the upstream reservoir  1  below the fluid surface  2 . The downstream end of the closed conduit  31  is oriented such that its exit is directed upward and it is interfaced to the lower end of the bellows  40 . The upstream end of the closed conduit  31  is equipped with an optional baffle  32 , to prevent entry of undesirable materials such as trash, debris, greases, oils and the like from entering or possibly interfering with the operation of the flow control system  30 . Although the optional baffle  32  is depicted in the form of an elbow oriented such that its entrance is directed downward, there are many ways to protect the inlet of the closed conduit  31  from the unwanted entry of undesirable materials. In some embodiments it is anticipated the closed conduit  31  may be protected by a screen, or by connecting its inlet to a surface skimming device. 
     The bellows  40  has an axis which is vertical and is made from rubber, polyurethane, plastic or any other any reasonably flexible, resilient and impervious material suitable for conveying the fluid  3 . Although there are many ways to interface the lower end of the bellows  40  to the closed conduit  31 , the lower end of the bellows  40  is connected to the closed conduit  31  by means of a flanged connection  35 . In some embodiments it is anticipated the lower end of the bellows  40  has a collar which fits tightly over the outside of the closed conduit  31  and is fastened to the closed conduit  31  with clamps. 
     The distal, upper end of the bellows  40  is equipped with a cap  45  which is made from metal, plastic or any other sufficiently rigid material suitable for exposure to the fluid  3 . The cap  45  has at least one fluid passageway  46  which provides an opening from the interior of the bellows  40 . The fluid passageway  46  is oriented horizontally and has an open area which is smaller than the cross sectional area of the inner dimension of the bellows  40 . In some embodiments, the cap  45  is a component which is separate, and is fastened to the upper end of the bellows  40 . In other embodiments, the cap  45  is made integral to the bellows  40 . 
     The bellows  40  is enclosed by a rigid tube  50 , an axis of which is vertical, and which has a slot  51  provided along the length of its axis of sufficient width such that the interior of the rigid tube  50  is freely and fluidly connected to the interior of the container  20 . Although only a single slot  51  is shown, it is anticipated that in some embodiments there may be more than one slot  51 . The interior dimension of the rigid tube  50  is sufficient to accommodate the exterior dimension of the bellows  40  such that the bellows  40  is free to expand upwardly, yet is restrained from moving laterally. The rigid tube  50  is made of metal, plastic or any other material which is suitable for exposure to the fluid  3  and is sufficiently rigid to maintain its axis vertical and resist the forces of hydrostatic pressure which are anticipated to act on its interior surfaces. 
     The container  20  can be fashioned from materials such as concrete, metal, plastic or any other material or combination of materials which provide adequate structural integrity and are also reasonably impervious and suitable for exposure to the fluid  3 . In some embodiments, the upper end of the container  20  may be open, and in other embodiments it may be closed, so long as the interior container  20  can be maintained at the ambient, atmospheric pressure. An overflow riser  90  is located downstream of the container  20  and is fluidly interfaced to the downstream drainage system  60 , at a point which is downstream from the container  20 . The overflow riser  90  is made of concrete, metal, plastic or any other material which has adequate structural integrity and is suitable for conveying discharges of fluid  3 . When the fluid surface  2  in the reservoir  1  has risen to a level above the upper rim  91  of the overflow riser  90 , the overflow riser  90  provides a means to accommodate an increased rate of discharge when the volumetric capacity of the reservoir  1  is in danger of being exceeded. Although both the container  20  and the overflow riser  90  are depicted as being positioned in the reservoir  1 , it is not required. In some embodiments it is anticipated that the container  20  may be located outside of the reservoir  1  and the overflow riser  90  may be connected to the downstream drainage system  60  at a point downstream from the container  20  by means of a pipe which is routed around the container  20 . The position of the overflow riser  90  within the flow control system  30  may be at any of a number of locations so long as its upper rim  91  is fluidly connected to the reservoir  1  and it is connected to the downstream drainage system  60  at a point which is downstream from the container  20 . 
     The bellows  40  is depicted in a less than fully expanded state and the fluid passageway  46  through the cap  45  is at an initial level, at which the fluid surface  2  in the reservoir  1  is at the same level, and is the minimum, controlled level, at which there is no flow and no discharge of fluid  3  from the flow control system  30  into the downstream drainage system  60 . 
     Referring to  FIG. 2 , a schematic view of a system of the present invention will now be described. The flow control system  30  and fluid handling system  10  are the same flow control system  30  and fluid handling system  10  depicted in  FIG. 1 , wherein the flow control system  30  is incorporated into a fluid handling system  10 , and wherein the flow control system  30  receives the flow of fluid  3  from an upstream reservoir  1  and discharges the flow to a downstream drainage system  60 . The fluid surface  2  in the upstream reservoir  1  has risen above the initial, minimum, controlled level and the fluid  3  is flowing through the flow control system  30  from the upstream reservoir  1 , through the optional baffle  32 , into the closed conduit  31 , upward through the bellows  40 , and out through the fluid passageway  46 , provided through the cap  45 , and into the interior of the rigid tube  50 , wherein it then freely discharges out through the slot  51  along the length of the vertical axis of the rigid tube  50  into the container  20  and out into the downstream drainage system  60 . Since the fluid passageway  46  through the cap  45  has an open area which is smaller than the cross sectional area of the inner dimension of the bellows  40 , the bellows  40  has expanded upward in response to the increase in system pressure caused by the rise of the fluid surface  2  in the upstream reservoir  1  and, in turn, the level of the fluid passageway  46  through the cap  45  has risen to a prescribed level which is below the fluid surface  2  in the upstream reservoir  1 , and the rate of flow through the flow control system  30  is maintained at the desirable release rate or range of release rates prescribed for the fluid handling system  10 . 
     Referring to  FIG. 3 , a perspective view of the distal, upper end of the bellows  40  of a first embodiment of the present invention will be described. The distal, upper end of the bellows  40  is fitted with a cap  45  through which a fluid passageway  46  is provided. The open area of the fluid passageway  46  is smaller than the area of the inner dimensions of the bellows  40 . Although the bellows  40  is depicted as having a circular cross section, the bellows  40  may have a cross section of any geometry and it is anticipated that in some embodiments the bellows  40  may have a cross section which is non-circular. Similarly, the fluid passageway  46  is also depicted as being a single, circular opening; however, it may be provided in any number of a plurality of openings and geometric configurations suitable for limiting the release rate to the desirable release rate prescribed for the application. The cap  45  is in the form of a plate which is firmly attached to the bellows  40  in a fluid tight manner by an array of fasteners  47 . The cap  45  can be made of metal, plastic, or any other material which provides sufficient strength and rigidity to convey the upward force of increasing pressure, through the array of fasteners  47  to the upper end of the bellows  40 . The fasteners  47  may be screws, bolts, pins, staples or any other type of fastener suitable for making a firm and fluid tight connection to the distal, upper end of the bellows  40 ; however, the fasteners are optional as a firm and fluid tight connection between the cap  45  and the upper end of the bellows  40  may also be accomplished by a flanged connection, or by welding, fusing or the use of adhesives. 
     Referring to  FIG. 3A , a perspective view of an alternate distal, upper end of the bellows  40  of a first embodiment of the present invention will be described. The distal, upper end of the bellows  40  is formed with an integral collar, into which a cap  45 , through which there is a fluid passageway  46  which has an open area less than the cross sectional area of the inner dimension of the bellows  40 , has been inserted and fastened to upper end of the bellows  40  in a firm and fluid tight manner with a hose clamp  48 . Although a single hose clamp  48  is depicted, it may be one or a plurality of hose clamps of any type and material suitable for making a firm and fluid tight connection between the integral collar provided at the upper end of the bellows  40  and that portion of the cap  45  which has been inserted into the integral collar at the upper end of the bellows  40 . Further, the hose clamp  48  is optional as a firm and fluid tight connection can also be accomplished by welding, fusing or the use of adhesives. Although the fluid passageway  46  is depicted as being a single, circular opening; it may be provided in any number of a plurality of openings and geometric configurations suitable for limiting the release rate to the desirable release rate prescribed for the application. 
     Referring to  FIG. 3B , a perspective view of the upper end of the bellows  40  of a second embodiment of the present invention will be described. The distal, upper end of the bellows  40  is fitted with a cap  45  through which a plurality of fluid passageways  46  have been provided, in an orientation which is vertical, such that the discharge from the interior of the bellows  40  is directed horizontally. Although a plurality of fluid passageways  46  are depicted, only a single fluid passageway  46  is required so long as it is of sufficient area to limit the flow rate to the desirable release rate for the application. When the fluid passageway(s)  46  are oriented vertically, as shown, it is not necessary that they have an open area which is less than the cross sectional area of the inner dimensions of the bellows  40 . The cap  45  is fastened to the upper end of the bellows  40  in a firm and fluid tight manner by any number of means which accomplish such a connection, and further, it is not necessary that the cap  45  be provided as a separate part, as it may be made integral to the bellows  40 . 
     Referring to  FIG. 3C , a perspective view of the distal, upper end of the bellows  40  of a third embodiment of the present invention will be described. The distal, upper end of the bellows  40  has been fitted with a cap  45 , through which a plurality of fluid passageways  49 , are provided in the form of a short tube oriented such that its exit into the interior of the container is directed downward. The fluid passageways  49  intersect the vertical axis of the cap  45  and open from the interior of the bellows  40 . Although a plurality of fluid passageways  49  are depicted, only a single fluid passageway  49  is required, so long as it is of sufficient area to pass the desired release rate for the application. Whereas the fluid passageways  49  intersect the vertical axis of the cap  45 , it is not necessary that they have an open area which is less than the cross sectional area of the inner dimensions of the bellows  40  and it is anticipated that the fluid passageways  49  may have open areas which are larger or smaller than the cross sectional area of the inner dimensions of the bellows  40 . The cap  45  is fastened to the upper end of the bellows  40  in a firm and fluid tight manner by any number of means which accomplish such a connection, and further, it is not necessary that the cap  45  be provided as a separate part, as it may be made integral to the bellows  40 . 
     Referring to  FIG. 4 , a perspective view of the rigid tube which encloses and restrains the bellows  40  of a first embodiment of the present invention from lateral movement will be described. The bellows  40 , an axis of which is vertical, is fitted within and enclosed by a rigid tube  50 , an axis of which is also vertical, and through which a plurality of slots  51  along the length of its axis are provided. The rigid tube  50  is made of metal, plastic or any other material which has sufficient rigidity to maintain it at an axis which is vertical and resist the forces of hydrostatic pressure which are anticipated to act on its interior surfaces. The rigid tube  50  has an inner dimension which is sufficient to accommodate the outer dimension of the bellows  40 , such that the bellows  40  is restrained against lateral movement, yet is free to expand upwardly when the fluid pressure in the interior of the bellows rises and thereby exerts a force on the underside of the cap  45  and raises the level of the fluid passageway  46  through the cap  45 , to the prescribed level which produces the desirable release rate for the application. Although a plurality of slots  51  along the axis of the rigid tube  50  are depicted, only a single slot  51  is required, so long as its width is sufficient to pass the desirable release rate, while accommodating free discharge through the fluid passageway  46  provided through the cap  45 . 
     Referring to  FIG. 4A , a perspective view of an alternate rigid tube  50  which encloses and restrains the bellows  40  of a first embodiment of the present invention from lateral movement will be described. The bellows  40 , an axis of which is vertical, is fitted within and enclosed by a rigid tube  50 , an axis of which is also vertical, through which a plurality of openings  52  are provided near its lower end. The rigid tube  50  is made of metal, plastic or any other material which has sufficient rigidity to maintain it at an axis which is vertical and resist the forces of hydrostatic pressure which are anticipated to act on its interior surfaces. The rigid tube  50  has an inner dimension which is sufficient to accommodate the outer dimension of the bellows  40 , such that the bellows  40  is restrained against lateral movement, yet is free to expand upwardly when the fluid pressure in the interior of the bellows rises and thereby exerts a force on the underside of the cap  45  and raises the level of the fluid passageway  46  through the cap  45 , to the prescribed level which produces the desirable release rate for the application. Although a plurality of round openings  52  are depicted near the lower end of the rigid tube  50 , only a single opening  52  of any geometric configuration is required, so long as the opening  52  has an area which is sufficient to pass the desirable release rate for the application, while accommodating a free discharge through the fluid passageway  46  provided through the cap  45 . 
     Referring to  FIG. 4B , a perspective view of an alternate means to restrain the bellows  40  of a first embodiment of the present invention from lateral movement will be described. The bellows  40 , an axis of which is vertical, is fitted within and enclosed by an array of rigid bars  55 , the axes of which are also vertical. The rigid bars  55  are made of metal, plastic or any other material which has sufficient rigidity to maintain them at an axis which is vertical and resist the forces of hydrostatic pressure which are anticipated to act on them. The array of rigid bars  55  has an inner dimension which is sufficient to accommodate the outer dimension of the bellows  40 , such that the bellows  40  is restrained against lateral movement, yet is free to expand upwardly when the fluid pressure in the interior of the bellows rises and thereby exerts a force on the underside of the cap  45  and raises the level of the fluid passageway  46  through the cap  45 , to the prescribed level which produces the desirable release rate for the application. The spaces  56  between the rigid bars  55  are sufficient to pass the desirable release rate for the application, while accommodating free discharge through the fluid passageway  46  provided through the cap  45 . Although three rigid bars  55  are depicted, any number of rigid bars  55  may be provided so long as they arrayed in such a fashion as to restrain the bellows  40  from lateral movement and the spaces  56  between the rigid bars  55  are sufficient to accommodate free discharge through the fluid passageway  46  provided through the cap  45 . Further, although the rigid bars  55  are depicted as having a round cross section, it is anticipated that they may be provided in any number of geometric cross sections such as rectangular or tubular. 
     Referring to  FIG. 4C , a perspective view of the rigid tube  50  which encloses and restrains the bellows  40  of a third embodiment of the present invention from lateral movement will be described. The bellows  40 , an axis of which is vertical, is enclosed within a rigid tube  50 , an axis of which is also vertical, and has two slots  51  along the length of its axis. The slots  51  are of sufficient width to freely accommodate the outer dimension of the tubular shaped, fluid passageways  49  protruding from the cap  45 , which has been fitted to or made integral to the distal, upper end of the bellows  40 . The rigid tube  50  is made of metal, plastic or any other material which has sufficient rigidity to maintain it at an axis which is vertical and resist the forces of hydrostatic pressure which are anticipated to act on its interior surfaces. The rigid tube  50  has an inner dimension which is sufficient to accommodate the outer dimension of the bellows  40 , such that the bellows  40  is restrained against lateral movement, yet is free to expand upwardly when the fluid pressure in the interior of the bellows rises and thereby exerts a force on the underside of the cap  45  and raises the level of the tubular shaped fluid passageways  49  provided through the cap  45 , to the prescribed level which produces the desirable release rate for the application. Although two slots  51  and two, tubular shaped fluid passageways  49  which protrude from the cap  45  and through the slots  51  are depicted, any number of slots  51  and tubular shaped, fluid passageways  49  may be provided, so long as the total area of the tubular shaped fluid passageway  49  or fluid passageways  49 , as the case may be, have an area which is sufficient to limit discharge to the desired release rate. 
     Referring to  FIG. 5 , a schematic view of an alternate system of the present invention will be described. The flow control system  30  is incorporated into a holding tank  4  wherein the fluid  3 , stored in the holding tank, is flowing through the flow control system  30  and into a downstream drainage system  60 . The flow control system  30  is positioned beneath an optional accessway  5 , through the top of the holding tank  4 , such that the flow control system  30  is easily accessed from the surface for inspection or maintenance. The accessway  5  is depicted as a manhole rim and cover; however, in some embodiments, it is anticipated that the accessway  5  may be provided in the form of a catch basin grate, hatch cover or any number of other suitable means to provide access from the surface into the interior of the holding tank  4 . The closed conduit  31  is made of plastic, metal, concrete or any other material which is suitable for conveying the fluid  3 , and is connected to the upstream reservoir  1  below the fluid surface  2 . The downstream end of the closed conduit  31  is oriented such that its exit is directed upward and it is interfaced to the lower end of an expanding conduit provided in the form of a bellows  40 . The upstream end of the closed conduit  31  is equipped with an optional baffle  32 , to prevent entry of undesirable materials such as trash, debris, greases, oils and the like from entering or possibly interfering with the operation of the flow control system  30 . Although the optional baffle  32  is depicted in the form of an elbow oriented such that its entrance is directed downward, there are many ways to protect the inlet of the closed conduit  31  from the unwanted entry of undesirable materials. In some embodiments it is anticipated the closed conduit  31  may be protected by a screen, or by connecting its inlet to a surface skimming device. 
     The bellows  40  has an axis which is vertical and is made from rubber, polyurethane, plastic or any other any reasonably flexible, resilient and impervious material suitable for conveying the fluid  3 . Although there are many ways to interface the lower end of the bellows  40  to the closed conduit  31 , the lower end of the bellows  40  is connected to the closed conduit  31  by means of a flanged connection  35 . In some embodiments it is anticipated the lower end of the bellows  40  has collar which fits tightly over the outside of the closed conduit  31  and is fastened to the closed conduit with clamps. 
     The distal, upper end of the bellows  40  is equipped with a cap  45  which is made from metal, plastic or any other sufficiently rigid material suitable for exposure to the fluid  3 . The cap  45  has at least one fluid passageway  46  which provides an opening from the interior of the bellows  40 . The fluid passageway  46  is oriented vertically or horizontally and has an open area which is smaller than the cross sectional area of the inner dimension of the bellows  40 . In some embodiments, the cap  45  is a component which is separate, and is fastened to the upper end of the bellows  40 . In other embodiments, the cap  45  is made integral to the bellows  40 . 
     The bellows  40  is enclosed by a rigid tube  50 , an axis of which is vertical, and which has a slot  51 , provided along the length of its axis, of sufficient width, such that the interior of the rigid tube  50  is freely and fluidly connected to the interior of the container  20 . Although only a single slot  51  is shown, it is anticipated that in some embodiments there may be more than one slot  51 . The interior dimension of the rigid tube  50  is sufficient to accommodate the exterior dimension of the bellows  40  such that the bellows  40  is free to expand upwardly, yet is restrained from moving laterally. The rigid tube  50  is made of metal, plastic or any other material which is sufficiently rigid to maintain its axis vertical and resist the forces of hydrostatic pressure which are anticipated to act on its interior surfaces. 
     The container  20  can be fashioned from materials such as concrete, metal, plastic or any other material or combination of materials which provide adequate structural integrity and are also reasonably impervious and suitable for exposure to the fluid  3 . The upper end of the container  20  is open and its upper rim  91  is positioned at a prescribed level such that if the fluid surface  2  rises above the level of the upper rim  91  of the container and the volumetric capacity of the holding tank  4  is at risk of being exceeded, the container  20  can also function as an overflow riser and provide a means to accommodate an increased rate of discharge. In some embodiments, the upper rim  91  of the container  20  may be notched, in any number of geometric configurations, to create one or more additional overflow weirs at prescribed levels below the upper rim  91  of the container  20 . Although it is most convenient to utilize the container  20  as the means to provide an increased rate of discharge when the volumetric capacity of the holding tank  4  is at risk of being exceeded, it is not required. In some embodiments it is anticipated that a separate means to provide overflow control will be provided. The container  20  has also been fitted with additional, optional, inlets  92 , which open from the interior of the holding tank  4  into the interior of the container  20 , at prescribed levels, and provide a means to gradually increase the rate of discharge through the flow control system  30  as the fluid surface  2  in the holding tank  4  rises. Although two inlets  92  are depicted, it is anticipated there may be any number of inlets  92  positioned at varying and prescribed levels along the vertical axis of the container  20 . Although the flow control system  30  is depicted as being positioned within the holding tank  4 , it is not required. In some embodiments it is anticipated that the container  20  may be located outside of the holding tank  4  and is housed in a separate chamber, such as a manhole, which is fluidly connected to the interior of the holding tank  4  and downstream drainage system  60 . 
     Referring to  FIG. 6 , a schematic view of a second alternate system of the present invention will be described. The flow control system  30  is incorporated into the bank of a reservoir  1  and is fluidly interfaced to the reservoir  1 . The flow control system  30  is positioned beneath an optional accessway  5 , through the top of the container  20 , such that the flow control system is easily accessed from the bank of the reservoir  1  for inspection or maintenance. The accessway  5  is depicted as a catch basin grate; however, in some embodiments, it is anticipated that the accessway  5  may be provided in the form of a manhole rim and cover, hatch cover or any number of other suitable means to provide access from into the interior of the container  20  from above. The closed conduit  31  is made of plastic, metal, concrete or any other material which is suitable for conveying the fluid  3 , and is connected to the upstream reservoir  1  below the fluid surface  2 . The downstream end of the closed conduit  31  is oriented such that its exit is directed upward and it is interfaced to the lower end of an expanding conduit provided in the form a bellows  40 . The upstream end of the closed conduit  31  is equipped with an optional baffle  32 , to prevent entry of undesirable materials such as trash, debris, greases, oils and the like from entering or possibly interfering with the operation of the flow control system  30 . Although the optional baffle  32  is depicted in the form of an elbow oriented such that its entrance is directed downward, there are many ways to protect the inlet of the closed conduit  31  from the unwanted entry of undesirable materials. In some embodiments it is anticipated the closed conduit  31  may be protected by a screen, or by connecting its inlet to a surface skimming device. 
     The bellows  40 , has an axis which is vertical, and is made from rubber, polyurethane, plastic or any other any reasonably flexible, resilient and impervious material suitable for conveying the fluid  3 . Although there are many ways to interface the lower end of the bellows  40  to the closed conduit  31 , the lower end of the bellows  40  is connected to the closed conduit  31  by means of a flanged connection  35 . In some embodiments it is anticipated the lower end of the bellows  40  has a collar which fits tightly over the outside of the closed conduit  31  and is fastened to the closed conduit with clamps. 
     The distal, upper end of the bellows  40  is equipped with a cap  45  which is made from metal, plastic or any other sufficiently rigid material suitable for exposure to the fluid  3 . The cap  45  has at least one fluid passageway  46  which provides an opening from the interior of the bellows  40 . The fluid passageway  46  is oriented vertically or horizontally and has an open area which is smaller than the cross sectional area of the inner dimension of the bellows  40 . In some embodiments, the cap  45  is a component which is separate, and is fastened to the upper end of the bellows  40 . In other embodiments, the cap  45  is made integral to the bellows  40 . 
     The bellows  40  is enclosed by a rigid tube  50 , an axis of which is vertical, and which has a slot  51  provided along the length of its axis, of sufficient width, such that the interior of the rigid tube  50  is freely and fluidly connected to the interior of the container  20 . Although only a single slot  51  is shown, it is anticipated that in some embodiments there may be more than one slot  51 . The interior dimension of the rigid tube  50  is sufficient to accommodate the exterior dimension of the bellows  40  such that the bellows  40  is free to expand upwardly, yet is restrained from moving laterally. The rigid tube  50  is made of metal, plastic or any other material which is sufficiently rigid to maintain its axis vertical and resist the forces of hydrostatic pressure which are anticipated to act on its interior surfaces. 
     The container  20  can be fashioned from materials such as concrete, metal, plastic or any other material or combination of materials which provide adequate structural integrity and are also reasonably impervious and suitable for exposure to the fluid  3 . An overflow weir  93  is provided, at a prescribed level, through the wall of the container  20  that is in communication with the fluid  3  in the reservoir  1 . The overflow weir  93  provides a means to accommodate an increased rate of discharge when the volumetric capacity of the reservoir  1  is at risk of being exceeded. The overflow weir  93  may be provided in any number of geometric configurations and any number of prescribed levels. Further, it is also anticipated there may be more than one overflow weir  93  provided through the walls of the container  20  which are in communication with the fluid  3  in the reservoir  1 . Although it is most convenient to utilize the container  20  as the means to provide an increased rate of discharge when the volumetric capacity of the reservoir  1  is at risk of being exceeded, it is not required. In some embodiments it is anticipated that a separate means to provide overflow control will be provided. 
     The bellows  40  is depicted in a less than fully expanded state and the fluid passageway  46  through the cap  45  is at an initial level, at which the fluid surface  2  in the reservoir  1  is at the same level, and is the minimum, controlled level, at which there is no flow and no discharge of fluid  3  from the flow control system  30  into the downstream drainage system  60 ; however, the container  20  has also been fitted with additional, optional, inlet  92 , which opens from the reservoir  1  to the interior of the container  20 . The optional inlet  92  is depicted below the fluid surface  2  in the reservoir  1 , and fluid  3  is flowing through the optional inlet  92  into the interior of the container  20  and out into the downstream drainage system  60 . When the optional inlet  92  operates at levels below the initial, minimum, controlled level, it provides a means to drain the level of the reservoir  1  below the initial, minimum, controlled level. Although, only one optional inlet  92  is depicted, it is anticipated there may be a plurality of optional inlets  92  depending upon the requirements of the specific application. Further, it is anticipated that any number of optional inlets  92  may be provided above the initial, minimum, controlled level depending on the requirements of the specific application to provide a means to gradually increase the rate of discharge through the flow control system  30  as the fluid surface  2  in the reservoir  1  rises. 
     Although the flow control system  30  is depicted as being positioned in the bank of the reservoir  1 , it is not required. In some embodiments it is anticipated that the container  20  may be located some distance downstream from the reservoir  1  and is housed in a separate chamber, such as a manhole, which is fluidly connected to the reservoir  1  and the downstream drainage system  60 . 
     Equivalent elements can be substituted for the ones set forth above such that they perform in substantially the same manner in substantially the same way for achieving substantially the same result. 
     It is believed that the system and method of the present invention and many of its attendant advantages will be understood by the foregoing description. It is also believed that it will be apparent that various changes may be made in the form, construction and arrangement of the components thereof without departing from the scope and spirit of the invention or without sacrificing all of its material advantages. The form herein before described being merely exemplary and explanatory embodiment thereof. It is the intention of the following claims to encompass and include such changes.