Abstract:
A method for conducting maintenance on a chromatography column ( 1; 51 ), said column comprising a column tube ( 32 ), a top end cell ( 20 ) and a bottom end cell ( 26 ), where during chromatography said column tube ( 32 ) is secured between said top end cell ( 20 ) and said bottom end cell ( 26 ). Said method comprises the step of rotating at least the top end cell ( 20 ) 180 degrees around a horizontal axis before maintenance is conducted to the top end cell ( 20 ).

Description:
FIELD OF THE INVENTION 
     The present invention relates to a stand for holding a chromatography column and to a method for conducting maintenance to a chromatography column. 
     BACKGROUND OF THE INVENTION 
     Chromatography columns are typically comprised of a column tube with a top end cell covering the top opening of the tube and a bottom end cell covering the bottom opening of the tube. A chromatography column with variable column height also comprises a plunger or adaptor integrated in the top end cell, which adaptor can be moved to different heights within the column tube. The top end cell (possibly integrated with an adaptor) and bottom end cell comprise further sample inlet/outlet, sample distribution means, filter, net, O-rings and seals. Filters, nets, distribution means, O-rings and seals may need to be replaced or cleaned after some time. A common problem during maintenance of chromatography columns is disassembly and assembly of parts. Due to the heavy parts of large chromatography columns typically a hoist is needed for separating them. However a number of hoist free maintenance solutions for chromatography columns have been described in different patents. For example in U.S. Pat. No. 6,736,974 a method of accessing the interior of a chromatography column without the use of a crane is described. A plunger is connected to a drive system which can raise the plunger above a top of the column cylinder thereby allowing intrusive maintenance. 
     Maintenance and replacement of different parts in the top end cell and the bottom end cell of a chromatography column is still difficult due to the heavy parts. 
     SUMMARY OF THE INVENTION 
     An object of the invention is to facilitate maintenance of chromatography columns. 
     A further object of the invention is to improve safety and convenience for the operator during maintenance. 
     This is achieved in a method for conducting maintenance on a chromatography column. 
     This is also achieved with a stand for holding a chromatography column. 
     Hereby, the top end cell could be rotated such that the filter, net and distribution means will be kept together by gravitational force which will simplify disassembly of the different parts. The different parts and fasteners are also more easily reached when the top end cell has been rotated. The top end cell does not need to be removed. The maintenance is performed without the use of a separate device and the stand itself serves as a maintenance device. 
     Suitable embodiments are described in the dependent claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1   a  shows one embodiment of a chromatography column and a stand according to the invention. 
         FIG. 1   b  shows the same chromatography column and stand as in  FIG. 1   a  but column tube removed. 
         FIGS. 1   c  and  1   d  show the same chromatography column and stand as in  FIG. 1   a  when the top end cell is rotated ( 1   c ) and has been rotated 180 degrees ( 1   d ). 
         FIG. 2  shows one of the legs of the stand according to one embodiment of the invention. 
         FIGS. 3   a - 3   d  show schematically a chromatography column according to one embodiment of the invention in different positions during the maintenance procedure. 
         FIGS. 4   a - 4   e  show schematically a chromatography column according to another embodiment of the invention in different positions during the maintenance procedure. 
         FIGS. 5   a - 5   d  show schematically a chromatography column according to another embodiment of the invention in different positions during the maintenance procedure. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIGS. 1   a - 1   d  show one embodiment of a chromatography column  1  and a stand  2  according to the invention.  FIG. 1   a  shows the chromatography column  1  in an assembled position provided on the stand  2 .  FIG. 1   b  shows the same chromatography column as in  FIG. 1   a  but disassembled. In this embodiment the stand  2  comprises two identical legs  3 , also shown in  FIG. 2 . The legs  3  comprise one vertically oriented rod  4 , which in its lower end  6  is fastened to the middle part of a horizontally oriented rod  8 . The horizontally oriented rod  8  is adapted to rest on the ground via two feet  10  positioned one in each end of the horizontally oriented rod  8 . Furthermore the vertically oriented rod  4  comprises a rotatable upper fastening means  12  and a lower fastening means  14  positioned below the upper fastening means  12 , i.e. closer to the lower end  6  of the vertically oriented rod  4 . The lower fastening means  14  can be adjusted vertically along the vertically oriented rod  4 . 
     Now referring to  FIGS. 1   a - 1   d  a top end cell  20  which is circular in shape comprises on its outer rim two diametrically opposed upper stand engaging means  22 . The upper stand engaging means  22  are adapted to be engaged with the rotatable upper fastening means  12  on the stand. The top end cell  20  comprises typically a sample inlet/outlet, a distribution system, a filter, a net, O-rings and seals (not shown). A bottom end cell  26  also circular in shape comprises typically also inlet/outlet, distribution system, filter, net, O-rings and seals. It comprises also on its outer rim two diametrically opposed lower stand engaging means  28 . The lower stand engaging means  28  are adapted to be engaged with the lower fastening means  14  on the stand. 
     The chromatography column also comprises a column tube  32  which during chromatography is positioned in between the top end cell  20  and the bottom end cell  26 . The top end cell  20 , the column tube  32  and the bottom end cell  26  thereby defines a volume where chromatography medium should be provided. The diameter of the column tube  32  is in this embodiment smaller than the outer diameter of the top end cell  20  and the bottom end cell  26 . An outer rim  34  of both the top end cell  20  and the bottom end cell  26  comprise a number of holes  38  adapted to receive there through tie bars  42 . The number of holes and tie bars can of course be varied. In  FIG. 1   b  six tie bars and holes are shown but it could be any number. One tie bar  42  is adapted to penetrate one hole each in the top end cell  20  and the bottom end cell  26  when the column tube  32  is positioned there between. The tie bar  42  is then secured by fasteners to both the top end cell and the bottom end cell. Hereby the column tube  32  is secured steadily in between the top end cell and bottom end cell. Fluid tightening means such as O-rings can be provided for prevention of leakage. 
     In  FIG. 1   b  the chromatography column and the stand of  FIG. 1   a  is shown where the bottom end cell  26  has been lowered, the tie bars  42  has been removed and the column tube  32  has been removed. The lower fastening means  14  of the stand  2  are as described above possible to adjust vertically along the legs  3  of the stand  2 .  FIG. 1   c  shows the same disassembled chromatography column as in  FIG. 1   b  where the top end cell  20  is about to rotate. In  FIG. 1   d  the top end cell  20  has been rotated 180 degrees. When the top end cell  20  has been flipped (rotated 180 degrees around a horizontal axis) maintenance is provided to the top end cell  20 . The maintenance could be to exchange or clean parts such as filter, net, distribution system and seals. This is more easily done when the top end cell  20  has been rotated in situ according to the invention. The maintenance work is also safer for the personal when the gravitational force is used to keep parts together. 
       FIGS. 3   a ,  3   b ,  3   c  and  3   d  show schematically the chromatography column  1  shown in  FIGS. 1 and 2  in different positions during the maintenance procedure. The maintenance procedure is described below with reference to  FIGS. 3   a ,  3   b ,  3   c  and  3   d.    
     In  FIG. 3   a  it is shown how a lifting device  51  such as a scissor jack or a pallet lifter is provided underneath and against the bottom end cell  26  of the chromatography column. It is also shown how the tie bars  42  are released from the bottom end cell  26 . The tie bars  42  are for example secured to the bottom end cell by nuts  53  as described above in relation to  FIG. 2 . By removing these nuts  53  the tie bars  42  can be released from the bottom end cell  26 . 
     In  FIG. 3   b  it is shown how the bottom end cell  26  and column tube  32  are lowered by use of the lifting device. The tie bars  42  can also be removed completely. The column tube  32  is removed. Depending on how large the column tube is it can be removed by hand or by some kind of lifting device. 
     In  FIG. 3   c  it is shown how the top end cell  20  is flipped, i.e. rotation in situ of the top end cell  20  180 degrees around a horizontal axis. This is possible because the upper fastening means  12  on the stand are rotatable. This could possibly involve the removal of a locking device for allowing the top end cell  20  to rotate. A locking device could also be provided for locking the top end cell  20  in the rotated position. 
     Now maintenance can be conducted to the top end cell  20 . This can involve disassembly of the parts constituting the top end cell, such as distribution system, nets, filter, O-rings and seals. Parts can be cleaned and parts can be exchanged. The rotated position of the top end cell  20  makes it easier and more convenient to disassemble the parts because the gravity force helps keeping the parts together even when the fasteners keeping them together have been removed. Hereby maintenance is facilitated and security improved. 
     In one embodiment of the invention the bottom end cell  26  is raised by use of the lifting device. This would make it easier to reach and release the fasteners keeping the parts of the bottom end cell together. Possibly the bottom end cell could also be flipped as the top end cell in order to make it even easier to disassemble the bottom end cell. In that case the lower fastening means  14  of the stand also need to be rotatable. The raising of the bottom end cell  26  is shown in  FIG. 3   d.    
     Now maintenance is conducted also on the bottom end cell  26 . This could involve disassembly of the parts constituting the bottom end cell, cleaning of the parts and/or exchange of parts. 
     In  FIG. 4   a - 4   e  another embodiment of the invention is shown schematically in different positions during the maintenance procedure. The same reference numbers are given to the same parts as described in relation to  FIGS. 1-4 .  FIG. 4   a  shows a chromatography column  51  provided on a stand  2 . The stand  2  can be the same stand as described in  FIG. 2 . The chromatography column  51  comprises a top end cell  20 , a bottom end cell  26  and secured there between a column tube  32 . The column tube  32  is secured between the top end cell  20  and the bottom end cell  26  by tie bars  42  passing through holes in the outer rim of both the top end cell and the bottom end cell as described above in relation to  FIG. 1 . In this embodiment two diametrically opposed additional tie bars  63  are provided with upper stand engaging means  65  positioned in the middle of these tie bars  63 . The upper stand engaging means  65  are adapted to engage into rotatable upper fastening means  12  of the stand  2 . Hereby the swiveling point is in the center of gravity of the column. The bottom end cell  26  is possibly further secured to the stand  2  by lower stand engaging means  28  adapted to engage into lower fastening means  14  of the stand. The lower fastening means  14  are as also described in relation to  FIG. 2  movable vertical along the stand. Furthermore column securing means  74  are provided on the two additional tie bars  63 . The column securing means  74  are keeping the column secured to the opposed end cell even if the closest end cell is removed. 
     In  FIG. 4   b  a lifting device for example a pallet lifter  51  is provided underneath the column. Lower fasteners  77  provided to the tie bars  42  and the additional tie bars  63  for keeping the bottom end cell  26  secured to the column tube  32  are removed. 
     In  FIG. 4   c  the tie bars  42  are removed and the bottom end cell  26  is lowered by use of the pallet lifter  51 . Maintenance can now be performed on the bottom end cell  26 . The column securing means  74  are now keeping the column tube  32  against the top end cell  20 . 
     In  FIG. 4   d  the bottom end cell  26  is raised up against the column tube  32  by use of the pallet lifter  51 . Then fasteners  77  are mounted on the additional tie bars  63  hereby keeping the bottom end cell  26  together with the column tube  32 . 
     In  FIG. 4   e  the pallet lifter  51  is removed and the column is rotated in situ 180 degrees around a horizontal axis. After the rotation the top end cell  20  is in the position where the bottom end cell  26  was from the beginning. Now the top end cell  20  can be lowered and maintenance can be provided to the top end cell in the same way as described for the bottom end cell in relation to the  FIGS. 4   b - 4   d.    
     Hereby, like in the embodiment described in relation to  FIGS. 1-3 , the rotated position of the top end cell  20  makes it easier and more convenient to disassemble the parts because the gravity force helps keeping the parts together even when the fasteners keeping them together have been removed. Hereby maintenance is facilitated and security improved. 
     One advantage with the method described in relation to  FIGS. 4   a - 4   e  where the whole column is rotated instead of only the top end cell is that the column tube needs not to be lifted out. This could be especially advantageous for larger columns. With this described method the maintenance procedure will also be exactly the same for both top and bottom end cell. 
     In  FIGS. 5   a - 5   d  another embodiment of the invention is shown schematically in different positions during the maintenance procedure. Most of the parts are the same as in  FIGS. 1-3  and are also given the same reference numbers as in  FIGS. 1-3 . These parts will not be further described here. In  FIG. 5   a  a lifting device  51  is provided underneath the column and the lower fasteners  53  are released from the tie bars  42 . 
     In  FIG. 5   b  it can be seen that column securing means  81  are provided to at least some of the tie bars  42  in this embodiment for keeping the column tube  32  in place against the top end cell  20  when the bottom end cell  26  is lowered for maintenance. 
     In  FIG. 5   c  it is shown that after maintenance of the bottom end cell  26  the bottom end cell  26  is raised against the column tube  32  with the lifting device  51 . Then the column securing means  81  are removed and the tie bars  42  are also removed. 
     In  FIG. 5   d  it is shown that the bottom end cell  26  is lowered together with the column tube  32  and the top end cell  20  has been rotated in situ 180 degrees around a horizontal axis for maintenance. 
     The embodiment described in relation to  FIGS. 5   a - 5   d  could be especially suitable when large column tubes are handled because there is no need to remove the column tube. 
     All patents, patent publications, and other published references mentioned herein are hereby incorporated by reference in their entireties as if each had been individually and specifically incorporated by reference herein. While preferred illustrative embodiments of the present invention are described, one skilled in the art will appreciate that the present invention can be practiced by other than the described embodiments, which are presented for purposes of illustration only and not by way of limitation. The present invention is limited only by the claims that follow.