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FIELD OF THE INVENTION 
   This invention relates to a device and method for controlling the rate of flow from storm water runoff through a catch basin or similar device. 
   BACKGROUND OF THE INVENTION 
   Storm water runoff can carry sediment from soil erosion and other residues from a retention pond or other water holding area if it is allowed to be released too rapidly. 
   The adverse effects of such uncontrolled storm runoff effluents are well documented. The Federal Clean Water Act (CWA) regulates storm water discharge through the National Pollutant Discharge Elimination System (NPDES) that require a storm water pollution prevention plan (SWP3) to be prepared for each site. The post-construction best management practices (BMP&#39;s) require a 48 hour draw down time for extended detention basins. (dry basins). The longer draw down period for storm water discharges are for water quality purposes. 
   This regulation mandates a rate of draw down that is substantially slower than previously allowed. The benefits of such a draw down rate are believed to be providing more time for small particle contaminants to settle in the detention basin bed. 
   The primary problem is there has been no catch basin overflow structures built or designed to handle such slow rates of discharge. Accordingly, a simple and efficient way to convert or retrofit existing structures to meet the new standards is needed. Similarly new structures need to be developed that can be designed with controlled runoff rates based on the surrounding requirements of the detention basin or ponds and therefore each new system ideally would be able to be custom sized for the conditions to achieve the desired rate of storm water draw down. 
   Several approaches to achieving controlled rates of flow have been attempted in storm water drainage systems. U.S. Pat. No. 4,522,533 discloses a tapered flow restriction with a cover plate having a predetermined aperture at an end. The tapered part being inserted into the end of a sewer pipe. The flow restrictor is used to prevent storm water backup in urban sewer systems which results in flooding of basements and other significant inconveniences. Similarly U.S. Pat. No. 5,080,137 teaches Vortex Flow Regulators for Storm Sewer Catch Basins, the flow being controlled by a spiraled shape to restrict the rate of flow initially and which increases in area outwardly along the spiral permitting large volume flows to the catch basin or manhole to be accommodated where it is installed. The spiral flow was believed to be less prone to clogging. U.S. Pat. No. 3,938,713 taught a Flow Regulator for sediment collecting chambers of a separating device. 
   None of these devices provides a way to optimally size or control the draw down rate for an overall catch basin system at rates of outflow less than 1.0 cfs. 
   One system used a plurality of conventional rip rap filled with gabion boxes aligned end to end to restrict the rate of flow of storm water runoff in areas under construction wherein high mud levels were commonly found. The problem with this flow restriction system is the effectiveness or flow rate changes are dependent on the amount of debris trapped in the system. 
   Other more sophisticated approaches relying on complete systems can be found in U.S. Pat. Nos. 6,783,683; 6,638,424; 5,707,527; 5,549,817 and 5,322,629 none of which teach a way to achieve such a long draw down time as 48 hours or longer to achieve water quality volume. 
   A feature of the present invention is it is adaptable to any pre-existing storm catch basin system 
   Another feature of the present invention is that it permits empirical analysis and verification of the draw down rate. 
   Another feature is the present invention can be adjusted or modified to increase or decrease the rate of draw down after it has been installed to insure regulatory conditions are precisely met without difficulty. 
   Changes in future regulatory draw down rates can be easily implemented. 
   SUMMARY OF THE INVENTION 
   A flow restriction device has an orifice plate, the orifice plate having a frontal surface area A and at least one opening for the passage of fluid of an area Oa, wherein Oa is less than A. The flow restriction device may also employ a screen debris plate, the screen debris plate having a plurality of spaced openings for the passage of fluid; the sum area of the openings being Σ Osp wherein Σ Osp is greater than Oa. 
   The flow restriction device preferably also includes a pipe having at least one threaded end and a first coupling for attaching to the at least one threaded end. The orifice plate is retained by the first coupling or the pipe or the combination when assembled. 
   The first coupling has an outside dimension larger than said pipe. 
   The flow restriction device of the preferred embodiment also has a second coupling for attaching to an opposite second end of the pipe; and wherein said screen debris plate is retained by the second coupling or the pipe or the combination when assembled. 
   The second end of said pipe is preferably also threaded and said second coupling is threaded to attach to said pipe at said second end. The second coupling has an outside dimension larger than said pipe. 
   The flow restriction device may alternatively use a pipe and one or more flanges in place of said couplings, wherein said pipe has one or more threaded ends and said one or more flanges have threads for securing said pipe in an opening in a wall. 
   The flange may have an end for retaining said orifice plate and a threaded joint for attaching to one end of the threaded pipe, wherein said orifice plate is removably retained. 
   The flow restriction device assembly may have a first flange having a central screen debris plate having a plurality of spaced openings and a projecting end; a second flange having a recessed portion and a projecting end; an orifice plate retained in said recessed portion; and wherein said first and second flange ends can be joined at said respective projecting ends. The flow restriction device assembly may further have a threaded pipe, said threaded pipe being joined to the respective projecting ends and interposed between ends of said flanges. 
   The method of restricting drainage flow from a catch basin has the steps of: placing a removable or modifiable first flow restrictor plate with one or more flow openings of a predetermined open area (Oa) in an outlet or orifice of a catch basin wall or drain pipe or in-line of a drain pipe; measuring the time required to draw down the catch basin after a first flush rain event; and increasing or decreasing the time to draw down by either removing the flow restrictor plate and replacing with a second flow restrictor plate having more or less flow opening area or modifying said first flow restrictor plate by plugging some of the flow area or increasing said flow area by adding to or enlarging the one or more flow openings; more area (Oa+) increasing flow volume, less area (Oa−) decreasing flow volume. 
   The method may further have the steps of: calculating the required increase or decrease of area (A) required to draw down the catch basin at a predetermined time after a first flush rain event; and re-measuring the time to draw down after a first flush rain event. 
   Definitions 
   Weir—as used herein refers to a wall or obstruction used to control flow from settling tanks or catch basins or ponds to ensure a uniform flow rate 
   First Flush Rain Event—as used herein refers to the small volume of runoff that occurs at the beginning of a rain storm. It carries with it concentrations of pollutants such as sediment, trash, heavy metals, oils, etc that have accumulated during dry weather between storms. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will be described by way of example and with reference to the accompanying drawings in which: 
       FIG. 1  is a perspective view of an exemplary catch basin overflow device including a submerged weir and a primary structure including a secondary weir overflow. 
       FIG. 1A  is a perspective view of the stones used in the submerged weir in an exemplary wire box enclosure. 
       FIG. 2A  is a partial cross sectional view of the submerged orifice with a preferred flow restrictor prior to assembly according to the preferred embodiment of the invention. 
       FIG. 2B  is a view of the flow restrictor of  FIG. 2A  shown assembled. 
       FIG. 3  is a perspective view of the screen debris plate. 
       FIG. 4  is a perspective view of an orifice end cap. 
       FIG. 5  is a partial cross sectional view of a first alternative according to the present invention installed in the catch basin overflow device. 
       FIG. 6  is a perspective exploded view of the first alternative embodiment of  FIG. 5 . 
       FIG. 7A  is a perspective view of a screen debris plate assembled to a flange portion from  FIG. 6  showing a partial cut away view of a quarter turn attachment for the screen debris plate. 
       FIG. 7B  is a perspective view of the screen debris plate and the flange portion of  FIG. 6  showing the quarter turn attachment of the screen debris plate. 
       FIG. 8  is a cross sectional view of the second alternative embodiment flow restrictor assembly attached through the submerged orifice. 
       FIG. 9A  is a first exploded view of the flow restrictor device of  FIG. 8  looking toward the screen debris end of the assembly. 
       FIG. 9B  is a second exploded view of the flow restrictor device of  FIG. 8  looking toward the variable orifice plate portions of the assembly, one orifice plate portion being on the screen debris sleeve, the other orifice plate portion being on the flange coupling. 
       FIG. 10  is a cross sectional view of a third alternative embodiment according to the present invention, the third embodiment of the invention employing the variable orifice plate portions of the assembly shown in  FIG. 8 , but in a two piece flange secured assembly. 
       FIG. 11  is an end plan view of the third embodiment shown in  FIG. 10 . 
       FIG. 12  is a cross sectional view of a flow restrictor device of  FIG. 10  with a pin for fixing the variable orifice size. 
       FIG. 13  is an end plan view of the flow restrictor device of  FIG. 12 . 
       FIG. 14  is a cross sectional view of a fourth alternative embodiment flow restriction device according to the present invention. 
       FIG. 15  is a plan view of the fourth alternative embodiment of the present invention taken from  FIG. 14 . 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   With reference to  FIG. 1  a perspective view of an exemplary catch basin  100  is shown. The catch basin  100  as illustrated has a submerged or at least partially submerged weir structure base  110 . The submerged weir structure base  110  is a concrete structure having four walls  111 ,  112 ,  113 ,  114  one of which is an inlet wall  111  cut with a rectangular weir opening  115  to allow storm water to inflow. As shown, the inlet wall  111  has a rock channel  120  in front of it to minimize the inflow of soil and to act as a pre-filter. 
   Inside the walls of the submerged weir structure base  110  is placed a primary concrete structure  150  surrounded by smaller stones  130 , preferably a mixture of #1 and #2 stone filled to a level preferably about equal to the height of the walls  111 ,  112 ,  113 ,  114 . In a more preferred embodiment these stones  130  are encased in gabion boxes  132  as shown in  FIG. 1A  to permit removal for cleaning and replacement. 
   Near the floor  116  of the submerged weir structure base  110  is a submerged orifice  1  covered in the bed of stones  130 , the stones  130  being a filtering means between the larger rocks  120  at the inlet  115  and the submerged orifice  1 . The submerged orifice  1  is an opening into the primary structure  150 . The primary structure  150  is the tall concrete structure set back on the floor  116  in the submerged weir structure base  110  and it has a primary overflow orifice  2  located in a wall  151  at a level just above the stone filter bed  130 . On the back side of the primary structure  150  are one or more outlet openings  4  to which a discharge or outlet pipe (not shown) can be connected. At the top of the primary structure  150  is a screen or grate  5  covered secondary weir overflow  3  for inletting storm water into the primary structure  150  when the level rises too rapidly to be accommodated by the submerged orifice  1  or primary orifice  2 . 
   Attached to the submerged orifice  1  is a flow restrictor device  10  according to the present invention. While shown in the orifice  1  of the wall  151 , the restrictor devices of the present invention can be used in any drainage orifice including drain pipes wherein the restrictor device may be attached at an end or as a coupler between pipe sections. With reference to  FIG. 2A  a cross sectional view of the preferred flow restricting device assembly  10  is shown unassembled. The assembly  10  has a pipe  12  with threaded ends  12 A,  12 B protruding through the wall  151  at the orifice opening  1 . On each end of the pipe  12  a threaded end cap coupling  14 ,  15  can be attached. The threaded couplings  14 ,  15  have a diameter or external dimension sufficiently large to securely hold the pipe  12  in the wall  151 . 
   At an upstream or inlet end  12 B of the pipe  12  is located a screen or perforated debris plate  16  having a plurality of openings Osp, the sum of the area of the opening being Σ Osp. The screen debris plate  16  as shown is held in place by the pipe  12  and coupling  15  when assembled.  FIG. 3  shows the screen debris plate  16  in an enlarged perspective view, an inner diameter portion  17 A being sized to fit inside the pipe  12  and the outer diameter portion  17 B has a surface to abut against the wall of the pipe  12 . As shown in  FIG. 2B , the coupling  15  when threaded onto the pipe  12  holds firmly the portion  17 B securing the plate  16 . 
   At a downstream end or discharge end  12 A of the pipe  12  is an orifice plate  18 . As shown in  FIG. 4 , the orifice plate  18  has a frontal surface area A on a wall  20  and at least one opening, aperture or cut out site  22  for the passage of fluid having an area of Oa, Oa being less than A. 
   In one preferred method, the orifice plate  18  may have no opening  22  until assembled or just prior to assembly. In that case an opening  22  can be cut or drilled through the plate wall  20  of a size Oa predicted to be sufficient for proper draw down to store the first flush rain event. In any case the sum of the area Σ Oa of the orifice opening is less than the area Σ Osp of the optional screen debris plate  16 , if such a plate  16  is used. 
   After a first flush rain event, the area Oa can be increased if needed by enlarging the orifice or opening  22  or by adding one or more additional orifice openings  22 . In any event the sum or enlarged open area Σ Oa should be less than the area Σ Osp so that the flow restriction is in fact regulated at the orifice plate  18 . 
   The flow restriction device  10  as shown in  FIG. 2B  has male threaded pipe ends  12 A,  12 B and mating female threaded couplings  14 ,  15 . This permits easy assembly and disassembly. Alternatively the couplings  14 ,  15  can be attached by gluing or solvent bonding directly to the pipe  12  if so the use of threaded ends is not required, but may be used if desired or the device  10  may employ one end solvent welded and the other end removably attached if so desired. In any event one of the primary benefits of the present invention relates to the fact that the restriction of the flow can be tuned or adjusted to precisely match a pre-existing catch basin  100 . This means that any pre-existing storm water drainage system can be retrofitted to meet the new slow draw down rate requirement without requiring a new system or costly modifications. 
   While the preferred embodiment as shown in  FIGS. 2A and 2B  uses a screen debris plate  16  it must be appreciated that the assembly  10  could optionally not use such a device. In such a case it is recommended that a pre-filtering device should be employed. 
   In  FIG. 1  as shown the pre-filtration device may be stones  130  such as #1 and #2 stones lying loose or retained in wire cages  132  as in  FIG. 1A  which can be removed and replaced as they clog or can be cleaned and flushed easily for reuse. 
   Again, such use of pre-filtration assists in capturing or blocking debris from entering the flow restrictor device  10  and changing the optimal flow rates by blocking some or all of the openings  22 . 
   A significant benefit of the present invention is that any maintenance crew can make the necessary installation and even if first time estimate of required orifice opening area Oa is wrong, a simple method of replacing or modifying the orifice plate  18  will be possible. To increase flow restriction to further slow the draw down rate the area Oa can be reduced by replacing the orifice plate with one having a small opening area. Conversely, the increase in flow rate to adjust the draw down time to a quicker rate or time is simply accomplished by increasing the opening area Oa by replacing the plate or simply drilling more holes or cutting, drilling or punching out a larger hole or otherwise modifying the already installed plate  18 . As shown in  FIG. 4 , the knockout grooves  23  permit the installation crew to select various sized openings  22 . 
   Since the plates  15 ,  16  and the overall device  10  are preferably made of HDPE or PVC such modification can easily be made in the field. 
   With reference to  FIGS. 5 and 6  a first alterative embodiment of the present invention is shown. In this alternative flow restriction device  30  the couplings and the pipe can be replaced by two flanges  32 ,  34 . One first flange  32  has a male threaded projected end  32 B and the opposite second flange  34  has a female threaded projecting end  34 A that can be attached to the male end  32 B of the first flange  32  thereby securing the two flanges  32 ,  34  to the wall  151  and creating a conduit or passage through the submerged orifice  1 . At the inlet end of the flange  32 , the screen debris plate  36  can be retained in a recessed area as shown in  FIGS. 7A and 7B . The orifice plate  38  preferably is removably retained in the same fashion in an external recessed area so that it can be replaced easily to increase or decrease the flow opening area Oa as previously discussed. Alternatively, the orifice plate  38  can be integral to the flange  34  and thus the entire flange  34  can be replaced or modified to change the orifice opening area Oa. 
   At the opposite inlet end of the device  30  the flange  32  may include an optional screen debris plate  36  which can be removably retained as shown in  FIGS. 7A and 7B  or can be made integral to the inlet flange  32 . 
   In principle, this alternative device works in the same fashion as the preferred device, however, it can be made with as few as two flange pieces, one with an integral orifice plate, the other flange having an integral screen debris plate if so desired. 
   In the event that the wall thickness of the primary structure  150  is greater than the flanges  32 ,  34  can accommodate, a pipe insert (not illustrated) can be employed having one end with a male thread and an opposite end with a female thread to span the wall and permit physical attachment of the flanges  32 ,  34 . 
   As shown the orifice plate  18 ,  38  or optional screen debris plate  16 ,  36  can be a separate part or integral to the couplings  14 ,  15  of  FIG. 2A ,  2 B or the flanges  32 ,  34 . The orifice plate  18 ,  38  or screen debris plate  16 ,  36  can be removably captively retained by the couplings  14 ,  15 ; the pipe  12 , the flanges  32 ,  34  or any combination thereof. The orifice plate  18 ,  38  can be glued to the couplings  14  or threaded into said coupling  14  or flange  34  or simply retained using slots or other mechanical restraining features as shown in  FIGS. 6 ,  7 A and  7 B; quarter turn tabs  35 ,  37  may secure the plates  16 ,  18 ,  36 ,  38  to the devices  10 ,  30 . In any event the precise method of attachment should simply insure the device  10 ,  30  is securely fixed to the wall  151  of the structure  150  through the orifice opening  1 . The use of the catch basin concrete wall  151  insures sufficient strength to prevent the device from dislodging. 
   With reference to  FIGS. 8 ,  9 A,  9 B a second alternative flow restrictor device  40  is illustrated. The device  40  employs a screen debris portion  46  having a cylindrical sleeve portion  47  and an end plate portion  49  with openings Osp. The end plate portion  49  has a plurality of slots  41  adapted to engage an orientation protrusion or key  43 . The screen debris portion can be slipped into the flanged coupling  44  and one of the slots  42  can be aligned over the projection or key  43 . The flanged coupling  44  has a male threaded portion  44 B that can be threadingly attached to the securing flange coupling  48  having female threads  48 A. 
   With reference to  FIG. 9B  as can be shown the screen debris portion  46  has a sleeve end plate portion  47 A of the cylindrical sleeve portion  47 . The sleeve end plate portion  47 A covered a portion of the end of the cylindrical sleeve leaving an orifice opening  47 B. The screen debris portion  46  fits into the interior of the flange coupling and when it is slid into the flange coupling  44  the opening  47 B can be blocked at least partially by the flange coupling end plate portion  44 A. The flange coupling end plate portion  44 A partially covers the cylindrical walls at an end of the thread portion  44 B of the flange coupling  44  leaving an orifice opening  44 C. As shown, the flange coupling end plate portion  44 A covers about 50% of the end and has semicircular area leaving a semicircular opening  44 C. The sleeve end plate portion  47 A of the sleeve  47  has a similar semicircular area leaving a semicircular orifice or open area  47 B, the orifice area  47 B being less than  44 C due to the wall thickness of the sleeve  47 . 
   Upon assembly, the semicircular opening  47 B can be blocked fully by the flange coupling end plate portion  44 A or can be opened from partially to fully opened dependent on the alignment with the opening  44 C with the opening  47 B. When assembled the parts  44 ,  46 ,  48  make a three piece assembly wherein the orifice opening Oa can be selected and is dependent on the alignment of the opening  44 C and  47 B relative to the end plates  47   a  and  44 A. The alignment can be maintained by the key  43  engaging one of the slots  42  as shown. 
   In this embodiment, the device  40  is simply adjusted by changing the orientation of the sleeved screen debris portion  46 . As in the other embodiments, the threaded portions  44 B,  48 A can be replaced by gluing. Similarly, when the optimal orifice opening Oa is found the sleeve can be glued into place if so desired. 
   With reference to  FIGS. 10 ,  11 ,  12  and  13  a third alternative embodiment flow restrictor device  50  of the present invention is shown as well as a variation of that device  50  with a pin. The device  50  as shown can be made as a two piece assembly. The first flanged portion  52  can be slipped into the orifice  1  of the wall  151  and secured to the wall using concrete fasteners  62 , as shown countersunk screws  62  which pass through flange holes  51 . This first flange has an end plate  54 B having a semicircular area leaving an orifice opening  54 C similar to the embodiment  40  found in  FIGS. 8 ,  9 A and  9 B. 
   In this embodiment, the device  50  has a sleeved portion  56  having an optional screen debris end plate  56 A glued, welded or otherwise integral to the sleeved portion  56  and at an opposite end an end plate  56 B of a semicircular area leaving an orifice opening  56 C. As shown in  FIG. 10 , the orifice openings  54 C and  56 C are blocked by the end plates  56 B,  54 B respectively. As in the previous device  40 , slots  57  can be placed in a plurality of locations around the circumference of the sleeve  56  such that when mated to a projection or key  58  on the first flanged portion  52  the orifice opening Oa can be selected. As in the other embodiments the opening Oa can be varied from blocked to fully open and virtually any size Oa therebetween based on the number of slots  57  used. 
   Once the optimum opening is determined the two parts can be permanently glued together if so desired. 
   With reference to  FIGS. 12 and 13 , the devices  50  can be further modified by using a pin  70  threaded into a flange opening  80 . The pin can be adapted to lock into a slot opening  57  the device simply snaps into a slot when the inner sleeve portion  52  is rotated. 
   With reference to  FIGS. 14 and 15  a flow restrictor device assembly  60  according to a fourth alternative embodiment of the invention is shown. In this embodiment two overlapping flange plates, an exterior screen debris plate  62  and an interior orifice plate  64  are shown as an assembly  60 . 
   The interior plate  64  is fastened to the wall  151  using concrete screws  61  through an opening  69 . Then the exterior screen debris plate  62  is snapped onto the interior orifice plate  64  as shown and the annular rib  65  fits in the groove  66  as shown. A key pin  68  is pressed into the slot  67 . 
   A plurality of openings or holes  72 ,  73 ,  74  of a variety of sizes are shown on the exterior screen debris plate and a plurality of orifice openings or slots  76 ,  77  are located on the interior orifice plate  64 . 
   By rotating the exterior plate  62  relative to the interior pate a change in the orifice opening Oa can be made. The opening holes  72 ,  73 ,  74  can be blocked completely or aligned with the openings or slots  76 ,  77  to be partially opened to fully opened resulting in a maximum flow. Accordingly, the opening area Oa is the area defined by the amount of opening area in alignment of the plurality of openings on the screen debris plate and the plurality of openings on the orifice plate. 
   One advantage to the assembly  60  is that it can be designed without requiring a size a specified to the submerged orifice dimension as such it can be designed to fit sizes from say 4.0 inches to 12 inches by way of example. The parts  62  and  64  can be designed pre-assembled with an opening on the exterior screen debris plate  62  that can be aligned with the opening  69  such that the entire screw head can pass through. As each screw is attached to the wall  151  the opening can be rotated to the next opening  69 . In this fashion the installation requires no other assembly other than selecting the estimated orifice size or area Oa. 
   In each embodiment certain locking keys and slots or fastening techniques are shown. Those skilled in the art will recognize various substitutions or variations can be used to accomplish the task. Accordingly such features are meant to be exemplary, but not intended to be limiting. 
   In each of the third, fourth and fifth alternative embodiments as illustrated in  FIGS. 8-15 , the orifice opening Oa is changed or selected by a rotation of a first part with one or more openings relative to a second part with one or more openings. In each case it is believed important that the openings are closely positioned if not abutted so that the aligned resultant orifice area Oa can be truly restricting the storm water flow and to minimize hydraulic effects trying to separate the parts. Accordingly the parts should be firmly secured together. 
   Furthermore, while the various orifices are shown as semicircular, circular or slots the exact shape of these apertures can be a matter of design choice and thus alterations in size and shape are contemplated to be within the scope of the present invention. 
   As shown the typical storm water runoff catch basin orifice has a diameter of about 6 inches. Small systems may exist having orifice diameters of less than 6 inches, or about 4 inches or less. While large systems may have orifice diameters between 6 and 12 inches. Regardless of the orifice diameter a flow regulator device  10 ,  30 ,  40 ,  50  as described herein can be fitted to mate to the orifice and provide the flow restrictor device with an orifice area Oa as described above. 
   The method of practicing the present invention allows the use of the water quality volume retained in the overall catch basin system or flood control detention pond to be part of the flood control volume. This is enabled by the use of any one of the flow restriction devices  10 ,  30 ,  40 ,  50  and  60  of the present invention which slows down the rate of drainage, but permits the captured storm water to drain over the prescribed period of draw down time to provide water quality volumes. 
   Variations in the present invention are possible in light of the description of it provided herein. While certain representative embodiments and details have been shown for the purpose of illustrating the subject invention, it will be apparent to those skilled in this art that various changes and modifications can be made therein without departing from the scope of the subject invention. It is, therefore, to be understood that changes can be made in the particular embodiments described which will be within the full intended scope of the invention as defined by the following appended claims.

Summary:
A feature of the present invention is it is adaptable to any pre-existing storm catch basin system. Another feature of the present invention is that it permits empirical analysis and verification of the draw down rate. Another feature is the present invention can be adjusted or modified to increase or decrease the rate of draw down after it has been installed to insure regulatory conditions are precisely met without difficulty. Changes in future regulatory draw down rates can be easily implemented. 
     A flow restriction device has an orifice plate, the orifice plate having a frontal surface area A and at least one opening for the passage of fluid of an area Oa, wherein Oa is less than A. The flow restriction device may also employ a screen debris plate, the screen debris plate having a plurality of spaced openings for the passage of fluid; the sum area of the openings being Σ Osp wherein Σ Osp is greater than Oa.