Abstract:
A system and a method tension a screen having a generally rectangular shape defined by a length and a width. The screen has a profile with a shape extending the length of the screen. A rod has a channel configured to receive the shape of the profile of the screen therein. The rod has a plurality of segmented portions such that a first segmented portion of the plurality of segmented portions is separable from a second segmented portion of the plurality of segmented portions. The screen is positioned on a frame. The rod is positioned parallel to the length of the frame on two sides. A clamping mechanism tensions the screen with respect to the frame.

Description:
BACKGROUND 
       [0001]    In certain industries and/or applications, separating one material from a second material is often desired and/or required. Further, the separation of solids and fluids is generally known in a variety of industries and/or applications. For example, industrial separators use screens to separate solids and/or fluids as desired. Also, the mining industry has many applications in which solids may be separated from fluids to extract a desired ore and/or metal during mining processes. Further, on-shore and/or off-shore drilling applications use various methods and/or equipment to separate solids from fluids in drilling processes. 
         [0002]    Conventional vibratory screen apparatus for sifting material generally utilize screens of either hook strip or pretensioned design. Hook strip screens generally have a single layer or multiple layers of mesh bonded together. The screens may be tensioned after the screens have been mounted in the basket of the vibratory screen apparatus. Two opposed ends of the screen are fitted with a turn back element to form a hook strip. The hook strip may be hooked around a tension rail which may be attached to the side wall of the basket. Typically, a tension bolt may be used. However, other loading means to apply tensioning and securing forces may be employed. Tightening the tension bolt may move the tension rail outwardly towards the walls of the basket to apply tension to the screen. 
         [0003]    Hook strip screens may be pretensioned prior to mounting in the basket by attachment of the screen mesh element to an apertured support plate, typically by means of an adhesive. A screen having a plurality of mesh layers may be pretensioned. In some designs, layers of fused mesh may be corrugated prior to mounting to an apertured support plate and the hooks applied thereafter to the mesh-plate combination. 
         [0004]    Hook strip screens have a number of disadvantages including the complex and time consuming mounting of the screen members in the basket which results in significant downtime of the vibratory screen apparatus and requires the use of multiple parts. Attaining the correct screen tension for the sieved material also involves intricate fine tuning. The screens may be easily damaged if too much force is applied when tightening the bolts or loading means to tension the screens. A further disadvantage is the relatively poor sealing between the screen and basket. The metal on metal seal often results in leakage. Unscreened material may pass through gaps between the screen and the basket and may mix with already screened material below the mesh screen. Attempts to overcome the poor seal by placing rubber strips and/or gaskets at the metal/metal interfaces require intricate and time-consuming fitting. The strips and/or gaskets frequently work loose during vibration and become lost or lodged in the vibratory machine which obstructs and/or damages the machinery. In addition, applying tension to the screen when tightening the tension bolt adds undesirable stresses to the machine frame. 
         [0005]    Pretensioned screens generally have one or more layers of mesh permanently bonded under tension onto a generally rigid steel and/or plastics material apertured plate support frame. The mesh screen may be flat or crowned. The screen and frame are inserted into the basket as a unit which requires no adjustment to the tension of the screen. The screen and frame are normally secured in the machine by clamps from above and/or below. The clamps may be hydraulic pistons, inflatable clamping bags, bolts, tapered elements and/or the like. 
         [0006]    Conventional pretensioned screen units with integral support frames have significant disadvantages. For example, conventional pretensioned screens may be bulky, heavy and difficult to handle, transport and store. Typically, the design may be complex, and the frames may be expensive to construct. Plastic injection molding is commonly used which is an inflexible method of construction. The frames utilize large amounts of material which require disposal when the screen units are replaced. The disposal is inconvenient, expensive and negatively impacts the environment. 
         [0007]    Over the life of the screen, the particles cause wear on the wire mesh. Damage causes a breach in the mesh. As a result, that area of the mesh allows larger particles to pass through than desired. After the damage occurs, the screen must be replaced or repaired. 
         [0008]    Thus, many conventional screens may be large and cumbersome to handle during transportation, installation and/or removal. Manipulating the screens is difficult for a single user. The large screens may also be rigid which increases the difficulty in removing the screen from the separator. Also, the rigid screens are difficult to transport and/or store. In certain situations in which the available space surrounding the separator is limited, maneuvering the screens for installation and/or replacement is challenging. 
     
    
     
       DESCRIPTION OF THE DRAWINGS 
         [0009]      FIG. 1  illustrates a prior art vibratory screen apparatus having a screen with a hook strip. 
           [0010]      FIG. 2  illustrates a detail view of the prior art hook strip located within box “A” of  FIG. 1 . 
           [0011]      FIG. 3  illustrates an elevation view of a vibratory screen apparatus having a screen rod tensioning system in accordance with embodiments disclosed herein. 
           [0012]      FIG. 4  illustrates a detail view of the screen rod tensioning system within box “B” of  FIG. 3 . 
           [0013]      FIG. 5  illustrates an elevation view of a vibratory screen apparatus having a screen rod tensioning system with an airbag in a loosened position in accordance with embodiments disclosed herein. 
           [0014]      FIG. 6  illustrates a detail view of the screen rod tensioning system with the airbag within box “C” of  FIG. 5 . 
           [0015]      FIG. 7  illustrates an elevation view of a vibratory screen apparatus having a screen rod tensioning system with an airbag in a tightened position in accordance with embodiments disclosed herein. 
           [0016]      FIG. 8  illustrates a detail view of the screen rod tensioning system with the airbag within box “D” of  FIG. 7 . 
           [0017]      FIG. 9  illustrates a side view of another embodiment of the screen rod tensioning system with an airbag in a loosened position as disclosed herein. 
           [0018]      FIG. 10  illustrates a side view of another embodiment of the screen rod tensioning system with an airbag in a tightened position as disclosed herein. 
           [0019]      FIG. 11  illustrates a side view of another embodiment of the screen rod tensioning system with an airbag as disclosed herein. 
           [0020]      FIG. 12  illustrates a perspective view of a screen rod tensioning system in accordance with embodiments disclosed herein. 
           [0021]      FIG. 13  illustrates a perspective view of a screen rod tensioning system in a rolled position in accordance with embodiments disclosed herein. 
       
    
    
     DETAILED DESCRIPTION 
       [0022]    The embodiments disclosed herein relate generally to a system and a method for filtering and/or separating materials. More specifically, embodiments disclosed herein relate to a system and a method for tensioning a screen. 
         [0023]    Screens may be used to filter particles in industrial filtration systems. For example, such separators may use screens to separate solids from fluids. To promote separation, vibrational and/or circular motion may be applied to the screen. 
         [0024]      FIG. 1  illustrates a vibratory screen apparatus, commonly referred to as a separator  10 . The separator  10  shown in  FIG. 1  has a hook strip screen  12 . The connection of the hook strip screen  12  is also illustrated in greater detail in  FIG. 2 . Generally, the hook strip screen  12  may have a single layer of mesh  13 . Multiple layers of mesh may also be bonded together. The mesh  13  may be tensioned after mounting the hook strip screen  12  in a basket  14  of the separator  10 . Two opposed ends of the hook strip screen  12  may be fitted with a turn back element  16  to form a hook strip  18  which may be hooked around a retaining portion  19  of a tension rail  20 . For simplicity,  FIG. 1  illustrates a left side connection for the hook strip screen  12 . However, the right side connection may be provided in the same manner. Further, a single deck is shown. However, the separator  10  may have multiple decks. 
         [0025]    For example, the tension rail  20  may be attached to a side wall of the basket  14 . The tension rail  20  may be attached via a tension bolt  24 . Tightening the tension bolt  24  may move the tension rail  20  outwardly towards the interior walls  22  of the basket  14  of the separator  10  to apply tension to the hook strip screen  12 . The retaining portion  19  of the tension rail  20  may press against the hook strip  18 . The hook strip screen  12  may normally be stretched over a crowned deck (not shown). The resulting arcuate profile of the hook strip screen  12  may retain rigidity of the hook strip screen  12  during vibratory motion of the separator  10 . 
         [0026]    Typically, the hook strip screen  12  may be located above a ball box  28 . The ball box  28  may be generally rectangular in shape. However, other shapes may be used. The ball box  28  may be held in the basket  14  of the separator  10  on a ball box rail  29 . The ball box  28  may contain balls and/or other objects (not shown) of various shapes and/or sizes therein. The objects may move during vibratory motion produced during operation of the separator  10 . The movement of the objects may cause impact with the hook strip screen  12  above the ball box  28  to impart movement of the solids on the hook strip screen  12 . The ball box  28  may be supported by rails  30  attached to the interior walls  22  of the basket  14  of the separator  10 . 
         [0027]    Referring to  FIGS. 3 and 4 , an embodiment of a screen rod tensioning system  100  is shown. For simplicity,  FIGS. 3 and 4  illustrate a left side connection for the screen rod tensioning system  100 . However, the right side connection may be provided in the same manner. 
         [0028]    In an embodiment, the screen rod tensioning system  100  has a screen  105 . The screen  105  may have a single layer of woven mesh wire or may be multiple layers of woven mesh wire. The screen  105  may be a mesh cloth. The screen  105  may have a mesh size to filter particles. For example, the screen  105  may have the mesh size to separate drill cuttings from circulated drill fluid. The mesh size as used herein refers to the size of the apertures in the screen  105 . 
         [0029]    The screen  105  may have a length L and a width W as shown in  FIGS. 12 and 13 . The screen  105  may have a profile  110  molded on the edge of the screen  105 . The profile  110  may be molded on opposing sides of the screen  105 . The profile  110  may be molded lengthwise on the screen  105 . The profile  110  may have a circular cross-section as shown. However, other shapes and/or cross-sections may be used, as desired. The profile  110  may be formed from a material that has sufficient rigidity to maintain the shape of the profile  110 . However, the profile  110  may be made from a material that may permit rolling the screen  105  widthwise along the width W instead of lengthwise along the length L. 
         [0030]    Thus, the screen rod tensioning system  100  may allow the screen  105  to be rolled widthwise instead of lengthwise. For example, a traditional five foot by twelve foot screen may require a twelve foot long tube for shipping and/or transport. The screen rod tensioning system  100  may allow the same size screen to be shipped in a five foot long tube. The reduction in size may improve the ease of handling the screen  105 . 
         [0031]    The screen rod tensioning system  100  may have a rod  115 . The rod  115  may have a channel  120  to receive the profile  110  formed on the edge of the screen  105 . For example, the channel  120  in the rod  115  may have a matching cross-section to accommodate the cross-section of the profile  110 . As shown, the circular cross-section of the profile  110  may fit within the circular cross-section of the channel  120 . The channel  120  may be sized slightly larger than the profile  110  so that the rod  115  may slide down the length L of the profile  110  of the screen  105  on both sides. 
         [0032]    Thus, the profile  110  of the screen  105  may be inserted into the rod  115  in the screen rod tensioning system  100 . As shown in  FIGS. 3 and 4 , the rod  115  may be held in place by the retaining portion  19  of the tension rail  20 . Tightening the tension bolt  24  may move the retaining portion  19  of the tension rail  20  outwardly towards the interior walls  22  of the basket  14  of the separator  10  to apply tension to the screen  105 . The retaining portion  19  of the tension rail  20  may also move the rod  115  outwardly towards the interior walls  22  of the separator  10  to apply tension to the screen  105 . 
         [0033]    The screen rod tensioning system  100  may also eliminate the need for sectional screens in the separator  10 . Some installations may not have adequate space around the separator  10  to install a full twelve foot screen, for example. For such installations, the use of sectional screens may be required. Typically, the sectional screens may be smaller sized screens installed adjacent to each other in the separator  10  to fill the basket  14  of the separator  10 . However, sectional screens may be cumbersome and may create additional opportunities for bypass of the slurry. 
         [0034]    As shown in  FIGS. 12 and 13 , the screen rod tensioning system  100  may reduce and/or eliminate the bypass opportunities by using shorter rods butted together. For example, the rod  115  of the screen rod tensioning system  100  may be segmented. For example, the screen rod tensioning system  100  may use two six foot rods arranged end-to-end instead of one twelve foot rod  115 . Due to limited space adjacent to the separator  10 , the profile  110  of the screen  105  may be guided into the channel  120  of the first six foot rod. Subsequently, the profile  110  of the screen  105  may be guided into the second six foot rod. In this manner, the full twelve foot length of the screen  105  may be installed in the separator  10 . Further, the bypass opportunities may be reduced and/or eliminated by using a full length screen of the screen rod tensioning system  100 . Further, the length of the rod  115  may vary based upon the particular requirements and/or applications of the user. 
         [0035]    In other embodiments, the screen rod tensioning system  100  may use different length rods arranged end-to-end on a common axis instead of one twelve foot rod  115 . As shown in  FIGS. 12 and 13 , for example, the screen rod tensioning system  100  may use three four foot rods  116  arranged end-to-end on the common axis instead of one twelve foot rod  115 . In an embodiment, the screen rod tensioning system  100  may use four three foot rods arranged end-to-end instead of one twelve foot rod  115 . The three four foot rods  116  arranged end-to-end on the common axis and/or the four three foot rods arranged end-to-end on the common axis may enable the screen  105  to be installed in the separator  10  in a simplified manner. For example, the three four foot rods  116  arranged end-to-end on the common axis may permit the screen to be inserted into the separator  10  one four foot segment at a time. 
         [0036]    Further, the screen rod tensioning system  100  may allow replacement of the screen  105  in a simple manner. During use of the screen  105  in industrial filtration systems, the screen  105  may become damaged. For example, the screen  105  may be used in the separator  10  to separate drill cuttings from drilling fluid in on-shore and/or off-shore oilfield drilling. Such a harsh environment may be destructive to the screen  105  over a period of extended use and/or from repeated exposure to the drill cuttings. Periodic inspections of the screen  105  may indicate that damage may have occurred to the screen  105 . The user may remove the screen  105  for replacement with a new screen  105 . In an embodiment, the three four foot rods arranged end-to-end may be removed from the separator  10  one four foot segment at a time. The screen  105  may be folded at the end of each four foot rod as each four foot rod is removed from the separator  10  to form four foot folded sections of the screen  105 . As shown in  FIG. 12 , the screen  105  may be rolled following the removal of the profile  110  and the first four foot rod from the separator  10 . Thus, using the four foot rods with the screen  105  may require less effort to remove the screen  105  from the separator  10 . Removal in such a manner may also be performed in a smaller area around the separator  10 . A replacement screen may subsequently be reinstalled into the separator  10 . 
         [0037]      FIG. 5  illustrates another embodiment of a screen rod tensioning system  200  in the separator  10 .  FIG. 6  illustrates an enlarged detail view of a portion within box “C” of the screen rod tensioning system  200  of  FIG. 5 . For simplicity,  FIG. 5  illustrates a left side connection for the screen rod tensioning system  200 . However, the right side connection may be provided in the same manner. Further, a single deck is shown in  FIG. 5 . However, the separator  10  may have multiple decks. 
         [0038]    As shown in  FIG. 5 , a ball box  201  may be located in the basket  14  of the separator  10 . The ball box  201  may have a top surface  202  and a bottom surface  203 . The top surface  202  of the ball box  201  and the bottom surface  203  of the ball box  201  may be arranged approximately parallel to each other. Further, each end of the ball box  201  may have an angled end  211 . The ball box  201  may be supported and/or held within the basket  14  by a ball box rail  204 . 
         [0039]    As shown in enlarged detail in  FIG. 6 , the ball box rail  204  may have a vertical portion  205  arranged between a lower portion  206  and an upper portion  207 . The lower portion  206  may have a channel  210  formed along the length of the ball box rail  204 . The upper portion  207  of the ball box rail  204  may have an angled interior surface  208 . The upper portion  207  may also have a seal  209 . The seal  209  may be a bubble gasket, a P-gasket and/or the like. The seal  209  may be formed of a flexible sealing material and may be deformable. 
         [0040]    The screen rod tensioning system  200  may have an airbag  222  located in the channel  210 . The airbag  222  may be formed of a flexible material. The airbag  222  may have a generally rectangular shape in cross-section. The airbag  222  may have a top portion  224 . The top portion  224  may be relatively flat as shown in  FIGS. 5  and  6 . The airbag  222  may be pneumatically or hydraulically inflated. After inflation of the airbag  222 , the top portion  224  of the airbag  222  may have an arcuate shape  225  in cross-section as shown in  FIGS. 7 and 8 . The top portion  224  may increase the height of the airbag  222 . 
         [0041]    In the embodiment shown in  FIGS. 5 and 6 , the airbag  222  may be uninflated.  FIGS. 7 and 8  illustrate the airbag  222  in an inflated state. The operation of the screen rod tensioning system  200  may be described with reference to  FIGS. 5-8 . Referring specifically to the enlarged detail shown in  FIGS. 6 and 8 , the airbag  222  may be inflated to provide tension to the surface of the screen  105 . As shown in  FIG. 6 , the screen  105  may be located on the top surface  202  of the ball box  201 . The screen  105  may be in a relatively loosened position. The bottom surface  203  of the ball box  201  may be located on the airbag  222  that may be mounted within the channel  210  of the lower portion  206  of the ball box rail  204 . 
         [0042]    The profile  110  of the screen  105  may be inserted within the channel  120  of the rod  115 . The rod  115  may be located on the angled end  211  of the ball box  201 . The rod  115  may be located below the angled interior surface  208  of the upper portion  207  of the ball box rail  204  without being in contact therewith. Also, the screen  105  may be located below the seal  209  on the upper portion  207  of the ball box rail  204  without being in contact therewith. The seal  209  may have a circular cross-section. 
         [0043]    As shown in  FIG. 8 , the airbag  222  may be inflated which may contact the bottom surface  203  of the ball box  201  to lift the ball box  201  upwards. As the ball box  201  may be raised upwards, the rod  115  may contact the angled interior surface  208  of the upper portion  207  of the ball box rail  204 . The rod  115  may also contact the angled end  211  of the ball box  201 . The upward pressure on the ball box  201  combined with the contact of the rod  115  with both the angled interior surface  208  of the upper portion  207  of the ball box rail  204  and the angled end  211  of the ball box  201  may urge the rod  115  in an outwardly and/or downwardly direction. The inflation of the airbag  222  on the right hand side of the ball box  201  may operate in the same manner. As a result, the forces on the rod  115  at each end of the ball box  201  may place the screen under tension and tighten the screen  105  against the top surface  202  of the ball box  201 . 
         [0044]    As shown in  FIG. 8 , the seal  209  may contact the screen  105  on the top surface  202  of the ball box  201 . The seal  209  may be compressed against the screen  105  to form a seal for the screen  105 . The rod  115  may be forced into contact with the angled interior surface  208  of the upper portion  207  of the ball box rail  204  and the angled end  211  of the ball box  201  to create a secondary seal for the screen  105 . 
         [0045]      FIGS. 9 and 10  illustrate an embodiment of another screen rod tensioning system  300  in the separator  10 .  FIG. 9  illustrates a side view of the screen rod tensioning system  300  in a loosened position as disclosed herein.  FIG. 10  illustrates the screen rod tensioning system  300  in a tightened position as disclosed herein.  FIGS. 9 and 10  illustrate a right side connection for the screen rod tensioning system  300 . However, the left side connection may be provided in the same manner. Further, a single deck is shown in  FIGS. 9 and 10 . However, the separator  10  may have multiple decks. 
         [0046]    As shown in  FIGS. 9 and 10 , wherein like numerals represent like parts, the ball box  201  may be located in the basket  14  of the separator  10 . The ball box  201  may have the top surface  202  and the bottom surface  203 . The top surface  202  of the ball box  201  and the bottom surface  203  of the ball box  201  may be arranged approximately parallel to each other. Further, each end of the ball box  201  may have the angled end  211 . The ball box  201  may be supported and/or held within the basket  14  by a ball box rail  304 . As shown in  FIGS. 9 and 10 , the screen rod tensioning system  300  may have multiple ball box rails  304  arranged above each other within the basket  14  of the separator  10 . 
         [0047]    As shown in  FIG. 9 , the ball box rail  304  may have a lower portion  306  and an upper portion  307 . The upper portion  307  may have a channel  310  that may be formed along the length of the ball box rail  304 . The lower portion  306  of the ball box rail  304  may have an angled surface  308 . The lower portion  306  may also have a seal  309 . The seal  309  may be a bubble gasket, a P-gasket and/or the like. The seal  309  may be formed of a flexible sealing material and may be deformable. 
         [0048]    The screen rod tensioning system  300  may have the airbag  222  located in the channel  310 . The airbag  222  may be made from a flexible material. The airbag  222  may have a generally rectangular shape in cross-section. The airbag  222  may have the top portion  224 . The top portion  224  may be relatively flat as shown in  FIG. 9 . The airbag  222  may be pneumatically or hydraulically inflated. After inflation of the airbag  222 , the top portion  224  of the airbag  222  may have the arcuate shape  225  in cross-section as shown in  FIG. 10 . The top portion  224  may increase the height of the airbag  222 . 
         [0049]    In the embodiment shown in  FIG. 9 , the airbag  222  may be uninflated.  FIG. 10  illustrates the airbag  222  in an inflated state. The operation of the screen rod tensioning system  300  may be described with reference to  FIGS. 9 and 10 . The airbag  222  may be inflated to provide tension to the surface of the screen  105 . As shown in  FIG. 9 , the screen  105  may be located on the top surface  202  of the ball box  201 . The screen  105  may be in a relatively loosened position. The bottom surface  203  of the ball box  201  may be located on the airbag  222  that may be mounted within the channel  310  of the upper portion  307  of the ball box rail  304 . 
         [0050]    The profile  110  of the screen  105  may be inserted within the channel  120  of the rod  115 . The rod  115  may be located on the angled end  211  of the ball box  201 . The rod  115  may be located below the angled surface  308  of the lower portion  306  of the ball box rail  304 . Also, the screen  105  may be located below the seal  309  on the lower portion  306  of the ball box rail  304  without being in contact therewith. The seal  309  may have a circular cross-section. 
         [0051]    As shown in  FIG. 10 , the airbag  222  may be inflated which may contact the bottom surface  203  of the ball box  201  to lift the ball box  201  upwards. As the ball box  201  may be raised upwards, the rod  115  may contact the angled surface  308  of the lower portion  306  of the ball box rail  304 . The rod  115  may also contact the angled end  211  of the ball box  201 . The upward pressure on the ball box  201  combined with the contact of the rod  115  with both the angled surface  308  of the lower portion  306  of the ball box rail  304  and the angled end  211  of the ball box  201  may urge the rod  115  in an outwardly and/or downwardly direction. The inflation of the airbag  222  on the left hand side of the ball box  201  may operate in the same manner. As a result, the forces on the rod  115  at each end of the ball box  201  may place the screen under tension and tighten the screen  105  against the top surface  202  of the ball box  201 . 
         [0052]    As shown in  FIG. 10 , the seal  309  may contact the screen  105  on the top surface  202  of the ball box  201 . The seal  309  may be compressed against the screen  105  to form a seal for the screen  105 . The rod  115  may be forced into contact with the angled surface  308  of the lower portion  306  of the ball box rail  304  and the angled end  211  of the ball box  201  to create a secondary seal for the screen  105 . Thus, the screen rod tensioning system  300  may use multiple ball box rails  304  to support multiple decks each having the screen  105  in tension over the top surface  202  of the ball box  201 . 
         [0053]      FIG. 11  illustrates an embodiment of yet another screen rod tensioning system  400  in the separator  10 .  FIG. 11  illustrates a side view of the screen rod tensioning system  400  as disclosed herein.  FIG. 11  illustrates a left side connection for the screen rod tensioning system  400 . However, the right side connection may be provided in the same manner. Further, a single deck is shown in  FIG. 11 . However, the separator  10  may have multiple decks. 
         [0054]    As shown in  FIG. 11 , wherein like numerals reference like parts, the ball box  201  may be located in the basket  14  of the separator  10 . The ball box  201  may have the top surface  202  and the bottom surface  203 . The top surface  202  of the ball box  201  and the bottom surface  203  of the ball box  201  may be arranged approximately parallel to each other. Further, each end of the ball box  201  may have the angled end  211 . The ball box  201  may be supported and/or held within the basket  14  by a ball box rail  404 . 
         [0055]    As shown in  FIG. 11 , the ball box rail  404  may have a vertical portion  405  that may be arranged between a lower portion  406  and an upper portion  407 . The lower portion  406  may have a channel  410  that may be formed along the length of the ball box rail  404 . The upper portion  407  of the ball box rail  404  may have an angled insert  408 . The angled insert  408  may be formed of a ultrahigh molecular weight (“UHMW”) material, for example. However, other materials may be used, as desired. The upper portion  407  may also have a seal  409 . The seal  409  may be a bubble gasket, a P-gasket and/or the like. The seal  409  may be made from a flexible sealing material and may be deformable. 
         [0056]    The airbag  222  may be located in the channel  410  in the screen rod tensioning system  400 . The airbag  222  may be made from a flexible material. The airbag  222  may have a generally rectangular shape in cross-section. The airbag  222  may have the top portion  224 . The top portion  224  may be relatively flat as shown in  FIG. 11 . The airbag  222  may be pneumatically or hydraulically inflated. After inflation of the airbag  222 , the top portion  224  of the airbag  222  may have the arcuate shape  225  in cross-section as shown in  FIGS. 7, 8 and 10 . The top portion  224  may increase the height of the airbag  222 . 
         [0057]    In the embodiment shown in  FIG. 11 , the airbag  222  may be uninflated. The airbag  222  may be filled pneumatically or hydraulically using a port  226  shown in  FIG. 11 .  FIGS. 7, 8 and 10  illustrate the airbag  222  in an inflated state. The operation of the screen rod tensioning system  400  may be described with reference to  FIG. 11 . The airbag  222  may be inflated to provide tension to the surface of the screen  105 . As shown in  FIG. 11 , the screen  105  may be located on the top surface  202  of the ball box  201 . The bottom surface  203  of the ball box  201  may be located on the airbag  222  that may be mounted within the channel  410  of the lower portion  406  of the ball box rail  404 . 
         [0058]    The profile  110  of the screen  105  may be inserted within the channel  120  of the rod  115 . The rod  115  may be located on the angled end  211  of the ball box  201 . The rod  115  may be located below the angled insert  408  of the upper portion  407  of the ball box rail  404  without being in contact therewith. Also, the screen  105  may be located below the seal  409  on the upper portion  407  of the ball box rail  404  without being in contact therewith. The seal  409  may have a circular cross-section. 
         [0059]    As shown in  FIGS. 7, 8 and 10 , the airbag  222  may be inflated which may contact the bottom surface  203  of the ball box  201  to lift the ball box  201  upwards. As the ball box  201  may be raised upwards, the rod  115  may contact the angled insert  408  of the upper portion  407  of the ball box rail  404 . The rod  115  may also contact the angled end  211  of the ball box  201 . The upward pressure on the ball box  201  combined with the contact of the rod  115  with both the angled insert  408  of the upper portion  407  of the ball box rail  404  and the angled end  403  of the ball box  201  may urge the rod  115  in an outwardly and/or downwardly direction. The inflation of the airbag  222  on the right hand side of the ball box  201  may operate in the same manner. As a result, the forces on the rod  115  at each end of the ball box  201  may place the screen under tension and tighten the screen  105  against the top surface  202  of the ball box  201 . 
         [0060]    After the airbag  222  may be inflated, the seal  409  may contact the screen  105  on the top surface  202  of the ball box  201 . The seal  409  may be compressed against the screen  105  to form a seal for the screen  105 . The rod  115  may may be forced into contact with the angled insert  408  of the upper portion  407  of the ball box rail  404  and the angled end  211  of the ball box  201  to create a secondary seal for the screen  105 . 
         [0061]    While the present disclosure has been described with respect to a limited number of embodiments, those skilled in the art, having benefit of this disclosure, will appreciate that other embodiments may be devised which do not depart from the scope of the disclosure as described herein. Accordingly, the scope of the present disclosure should be limited only by the attached claims.