Patent Publication Number: US-7581407-B1

Title: Method of using dry cryogenic shipping container

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
   The present application is a divisional application based on U.S. patent application Ser. No. 11/257,936, filed Oct. 25, 2005. 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   This application relates to a dry cryogenic shipping container and, more specifically, to a dry cryogenic shipping container having a removable absorbent. 
   2. Background Information 
   Cryogenic shipping containers are used to transport materials at temperatures well below the freezing point of water. The materials transported at cryogenic temperatures are typically biologically active, such as, but not limited to, tissue samples and microorganism cultures. Hereinafter these materials will be identified as “use materials.” The typical cryogenic shipping container, similar to many storage devices for cryogenic liquids, included a Dewar flask, or similar construct, having an outer shell, an inner shell, and a vacuum therebetween. The inner and outer shells were coupled at a neck which defines a passage into the interior of the inner shell. A shipper core, typically a hollow cylinder, was disposed within, and coupled to, the inner shell. The inner shell had an inner diameter that was greater than the diameter of the shipper core. Thus, there was an annular gap between the shell and the shipper core. The shipper core may have also included a support structure for holding another containment device, such as, but not limited to, a canister or sample container. 
   When prepared for transport or storage, a cryogenic shipping container included a use material disposed in a sample container, which in turn was contained in a removable canister. The canister was then disposed in the shipper core. The shipper core, as noted above, was coupled to the inner shell. A cryogenic liquid was disposed in the annular gap between the shell and the shipper core. The container was closed by an insulated cap as was known in the art. This basic configuration, while useful, allowed cryogenic liquid to slosh about within the inner shell. Such a fluid movement is undesirable as it enhanced evaporation; the cryogenic liquid could splash on the use material, and cryogenic liquids can be dangerous to touch. 
   To reduce the amount of free cryogenic liquid in a cryogenic shipping container, absorbent materials were disposed in the annular gap. The absorbent materials were typically a rigid foam or another moldable material that could be disposed within the inner shell while maintaining a cavity sized to accept the shipper core. This absorbent material was, effectively, sealed in the inner space of the inner shell when the shipping core was coupled to the inner shell. In operation, the cryogenic liquid was poured into the inner space and allowed to be absorbed by the absorbent material. Any excess cryogenic liquid was removed prior to placing a sample container in the shipping core. As the cryogenic liquid was trapped in the absorbent materials, this type of cryogenic shipping container was identified as a “dry” cryogenic shipping container. 
   The disadvantage to using the dry cryogenic shipping container is that the absorbent material may become contaminated by the use materials. Once the absorbent materials become contaminated, the cryogenic shipping container should not be used again. Thus, the relatively expensive cryogenic shipping container may be rendered useless due to the contamination of the relatively inexpensive absorbent material. 
   There is, therefore, a need for a dry cryogenic shipping container that may be reused. 
   There is a further need for a dry cryogenic shipping container having a removable absorbent material. 
   SUMMARY OF THE INVENTION 
   These needs, and others, are met by the present invention which provides a dry cryogenic shipping container having a removable absorbent material. The structure of the metal components of the dry cryogenic shipping container remains generally similar to the dry cryogenic shipping container of the prior art. That is, the metal components are structured to be a Dewar&#39;s flask having an outer shell, an inner shell disposed within and spaced from the outer shell, and a cap. The outer shell and inner shell define a plenum wherein a vacuum is pulled. The inner shell defines an inner space. The outer shell and inner shell are coupled to each other at a neck that defines a passage into the inner space. Within the inner space is an absorbent assembly having a body with a central cavity. The absorbent assembly body is formed by a plurality of removable absorbent assembly elements. That is the absorbent assembly elements are sized to pass through the passage into the inner space. As such, after use, the absorbent assembly body elements may be removed and the remaining components may be sterilized. After sterilization, new absorbent assembly body elements are inserted into the inner space and the dry cryogenic shipping container is used again. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A full understanding of the invention can be gained from the following description of the preferred embodiments when read in conjunction with the accompanying drawings in which: 
       FIG. 1  is a side exploded view of a dry cryogenic shipping container. 
       FIG. 2  is a top view of a dry cryogenic shipping container. 
       FIG. 3  is top cross-sectional view of an alternate dry cryogenic shipping container. 
       FIG. 4  is top cross-sectional view of another alternate dry cryogenic shipping container. 
       FIG. 5  is a flow chart of the method. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   As used herein the phrase “sterilizable material” means a material that may be substantially sterilized either by heat, a chemical agent, radiation, or a combination thereof. 
   As used herein, the word “sample container” shall mean any container, such as, but not limited to, a vial or straw, used to store or transport a use material. 
   As used herein, the word “absorbent” shall mean a material that takes up another material, including an adsorbent material. 
   As shown in  FIG. 1 , a shipping container  10  includes a first, outer shell assembly  20 , a second, inner shell assembly  40 , and an absorbent assembly  60 . The first, outer shell assembly  20  has a body  22  defining an enclosed space  24  and having an opening  26 . The second, inner shell assembly  40  has a body  42  defining an inner space  44  and having an opening  46 . The second, inner shell assembly body  42  is disposed within, and generally spaced from, the first, outer shell assembly body  22 , thereby forming a generally airtight plenum  28  within the enclosed space  24 . A vacuum is pulled in the plenum  28 . The second, inner shell assembly body  42  and the first, outer shell assembly body  22  are coupled together at the openings  26 ,  46 , thereby forming a passage  30  into the inner space  44 . There may be an elongated tube, or neck  32 , extending between the first, outer shell assembly opening  26  and the second, inner shell assembly opening  46  that defines the passage  30 . The first, outer shell assembly  20  further includes an insulated cap  34  structured to close the passage  30 . The first, outer shell assembly  20  and the second, inner shell assembly  40  are made from a sterilizable material such as, but not limited to, stainless steel or aluminum. In this configuration, the outer shell assembly  20  and the inner shell assembly  40  form a Dewar&#39;s flask. 
   The second, inner shell assembly  40  may further include a shipper core  50 . The shipper core  50  is a removable container sized to pass through the passage  30 . The shipper core  50 , preferably, has a length sufficient to extend between the bottom of the second, inner shell assembly body  42  and partially into the passage  30  so that the shipper core  50  does not fall into the inner space  44 . The shipper core  50  further is structured to support a sample container  52 , or a support structure  54  in which a sample container  52  may be stored. The support structure  54  is typically, but is not limited to, a canister  53  or a hollow cane  56  (both described below). Thus, a sample container  52  of use material may be disposed in the shipper core  50 , which is, in turn, disposed within the second, inner shell assembly body  42 . The passage  30  may then be sealed by the cap  34  thereby substantially thermally insulating the use material. 
   Preferably, the shipping container  10  has a generally elongated, cylindrical shape. The first, outer shell assembly body  22  has a generally cylindrical lower portion  70  having a first diameter and a tapered upper portion  72  wherein the diameter reduces to be adjacent to the neck  32 . The second, inner shell assembly body  42  is generally cylindrical having a second diameter. The second, inner shell assembly body  42  diameter is smaller than the lower portion  70  diameter. The neck  32  is generally cylindrical having a third diameter that is, preferably, smaller than the second, inner shell assembly body  42  diameter. That is, to maximize the storage space within the inner space  44 , the second, inner shell assembly body  42  diameter is larger than the diameter of the neck  32 . The shipper core  50  is also cylindrical, preferably, having a diameter that is almost the same size of the neck  32 . In this configuration, the shipper core  50  has a cross-sectional area that is less than the cross-sectional area of the second, inner shell assembly body  42 . Thus, in the preferred embodiment, with the shipper core  50  disposed in the inner space  44 , there is an annular space  74  between the shipper core  50  and the second, inner shell assembly body  42 . The absorbent assembly  60  is disposed in the annular space  74 . 
   The absorbent assembly  60  has a plurality  62  of removable absorbent elements  64 . In the preferred embodiment, the absorbent elements  64  are socks  65 . The socks  65  are elongated, preferably a generally cylindrical body having a cross-sectional area sufficiently small enough to pass through the passage  30 . Each sock  65  includes a flexible covering  66 , which may be fabric, and a granular filler material  68 . The filler material  68  is, preferably, made from fumed silica or another absorbent/adsorbent material. The socks  65  have a length sufficient to extend between the bottom of the second, inner shell assembly body  42  to a level just below the passage  30 . The plurality  62  of absorbent elements  64  include a number of socks  65  sufficient to substantially fill the inner space  44  except for a cavity  69  about the size of the shipper core  50 . That is, the socks  65  are individually installed into the inner space  44  and moved to be adjacent to the second, inner shell assembly body  42 , that is, into the annular space  74 , thereby leaving a cavity  69  generally aligned with the passage  30 . That is, the cavity  69  is disposed generally along the longitudinal axis of the inner shell assembly  40 . The shipper core  50  is then inserted into the cavity  69 . Prior to insertion of the shipper core  50 , the socks  65  may extend into the space to be occupied by the shipper core  50 . During the installation of the shipper core  50 , however, the shipper core  50  will contact any socks  65  extending into the space to be occupied by the shipper core  50  and, due to the nature of the flexible covering  66 , move the socks  65  out of the space to be occupied by the shipper core  50 . This compression of the socks  65  also acts to squeeze the socks  65  together thereby reducing any gaps between the socks  65 . When the shipper core  50  is installed, the socks  65  fill substantially all of the annular space  74 . 
   In an alternate embodiment, shown in  FIG. 3 , the absorbent assembly  160  includes a body  162  formed of removable absorbent elements  164  that are generally rigid members  165 . The rigid members  165  are structured to form a cavity  169  generally aligned with the passage  30 . The cavity  169  is sized to accommodate the shipper core  50 . Each rigid member  165  is sized to pass through the passage  30 . Thus, the absorbent assembly body  162  may be removed from, or installed in, the inner space  44 . The rigid members  165  are structured to absorb a cryogenic liquid and are, preferably, made from fumed silica or another absorbent/adsorbent material. Again, the absorbent assembly body  162  is disposed in the annular space  74 . The rigid members  165  therefore are preferably shaped as elongated, truncated wedges with a generally circular outer edge and a generally circular inner edge. That is, to use a baked goods analogy, the rigid members  165  are shaped as pieces of a doughnut that has been cut into pie slices. This shape allows the rigid members  165  to be inserted through the passage  30  and assembled into the absorbent assembly body  162  within the inner space  44 . As shown in  FIG. 3 , as the last rigid member  165 A to be installed must be moved radially to be installed, the last rigid member  165 A is shaped as a quadrilateral sized to fit between adjacent wedge-shaped rigid members  165 . 
   As shown in  FIG. 4 , in another alternate embodiment the absorbent assembly  260  includes a body  262  formed of removable absorbent elements  264  that are identical rigid members  265 . In this embodiment, the inner shell assembly body  242  and the neck  32  have the same diameter. This configuration maximizes the spacing between the outer shell assembly body  222  and the inner shell assembly body  242 . In this embodiment, the shipper core  250  has a diameter that is smaller than the diameter of the inner shell assembly body  242 , thereby creating the annular space  274 A. Again, the absorbent assembly body  262  is disposed in the annular space  274 A. However, because the axial end of the absorbent assembly body  262  is exposed and accessible, all rigid members  265  are shaped as elongated, truncated wedges with a generally circular outer edge and a generally circular inner edge. 
   The sample containers  52  may be disposed in a canister  53  having a handle  55 . The canister  53  is sized to fit within the shipper core  50  and is a tube having a closed lower end. The canister handle  55  extends upwardly from the canister  53  and, when placed in a shipper core  50  that is disposed in the inner space  44 , the handle  55  extends through the neck  32 . In this configuration, the handle  55  may be grasped by a user (who is wearing protective gloves) or the handle  55  may be coupled to the insulated cap  34 . Thus, a user may lift the canister  53 , and the sample containers  52  disposed therein, by lifting the insulated cap  34 , if the handle  55  is coupled thereto, or by utilizing the handle  55 . Additionally, for smaller sample containers  52 , canes  56  may be utilized. A cane  56  is, essentially, a hollow tube in which small sample containers  52  may be placed. One or more canes  56  may then be disposed in a shipping core  50  or a canister  53 . 
   Because the absorbent assembly  60 ,  160 ,  260  may be removed, the shipping container  10  may be sterilized and reused. That is, the method of using the shipping container  10  includes the steps of inserting  300  removable absorbent assembly  60 ,  160 ,  260  into a shipping container inner space  44 , inserting  301  a shipper core  50  into the inner space  44 , filling  302  the inner space with a cryogenic liquid, disposing  304  a use material in the shipper core  50  for a period of time, removing  306  the use material from said absorbent assembly shipping core  50 , removing  307  the shipper core  50 , removing  308  the absorbent assembly  60 ,  160 ,  260  from the inner space  44 , and sterilizing  310  the inner space of said inner shell assembly body  42 . After sterilization  310 , the shipping container  10  may be prepared for reuse by inserting  312  a different removable absorbent assembly  60 ,  160 ,  260  into the inner space  44 . The shipping container  10  may be reused by refilling  314  the inner space  44  with a cryogenic liquid. The step of filling  302  the inner space with a cryogenic liquid, or the step of refilling  314  the inner space  44  with a cryogenic liquid, may include the additional steps of allowing  316  the cryogenic liquid to be absorbed by the absorbent assembly  60 ,  160 ,  260 , and removing  318  any excess cryogenic liquid. If a canister  53  is used, the method also includes the steps of placing  320  a use material in a canister  53 , placing  322  the canister  53  in the shipper core  50 , and removing  324  the canister from the shipper core  50 . 
   While specific embodiments of the invention have been described in detail, it will be appreciated by those skilled in the art that various modifications and alternatives to those details could be developed in light of the overall teachings of the disclosure. For example, the second, inner shell assembly  40  may have a different shape, such as spherical or rectangular. A change in the shape of the inner space  44  will accommodate absorbent elements  64  having different shapes. Accordingly, the particular arrangements disclosed are meant to be illustrative only and not limiting as to the scope of invention which is to be given the full breadth of the claims appended and any and all equivalents thereof.