US 20070210090 A1
Disclosed is a transport container for shipping frozen material, particularly biological tissue samples. Said transport container comprises a jacket-shaped insulation (superinsulation) and a removable inner container (44) which is provided with at least one coolant chamber (47) with a coolant filling (47′), and at least one chilling chamber (46) that is located inside the coolant chamber (47). The coolant, e.g. mercury having a melting temperature of about −39° C., is permanently and hermetically enclosed in the coolant chamber (47) and is solidified in a freezing process using liquid nitrogen, for example, before being shipped. The chilling chamber (46), and thus the sample, is maintained at said temperature level during shipping while the coolant or mercury melts slowly.
30. A transport container for keeping frozen material chilled, comprising an insulating chamber; an insulation which is a superinsulation with a coefficient of thermal conductivity λ of ≦0.005 W/m K and encloses said insulating chamber; an inner container removably arranged in said insulating chamber, said inner container having at least one chamber for the material and at least one refrigerant chamber which is permanently hermetically sealed; and a refrigerant located in said refrigerant chamber and giving off cold by solid/liquid phase transformation, said refrigerant being a pure organic substance undergoing the phase transformation between solid and liquid state in a temperature range from −15 ° to −100° C., and having a heat of melting of at least 50 J/ml.
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The invention relates to a transport container for keeping frozen material chilled, in particular frozen biological tissue samples or cell cultures, with an insulation which encloses an insulating chamber, with an inner container which is removably arranged in the insulating chamber and receives the frozen material in a chamber, and with a refrigerant which gives off cold by phase transformation.
A long-known measure for keeping material chilled is to put the material in an insulating container and in this way protect it from exposure to heat. In particular in the case of a transport container, however, there are limits to the wall thickness of the insulation, and consequently the insulating effect. Therefore, in particular in the case of relatively long storage or transporting times, there is no alternative but to ensure that penetrating heat is compensated by corresponding production of cold, in order to avoid a damaging rise in the temperature or even thawing of frozen material.
It is known to provide the cold that is required to compensate for heat flowing in by means of a refrigerant at low temperature, which is introduced in addition with the material into the correspondingly overdimensioned insulating chamber of the transport container. In this case, there is no need for the expense of a chilling device with media that has to be circulated. Exploiting the phase transformation of the refrigerant in the solid→liquid transition (heat of melting), liquid→gaseous transition (heat of evaporation) or solid→gaseous transition (heat of sublimation) allows a constant temperature to be achieved for the duration of the transformation, which depends on the quantity involved.
Known examples of such refrigerants used in transport containers are ice (water), dry ice (carbon dioxide) and liquid nitrogen. While ice has too high a melting point, of 0° C., to be used for keeping frozen material chilled, the temperature of sublimation of solidified carbon dioxide and the temperature of ebullition of liquid nitrogen are significantly below the customary temperatures of frozen material, so that to avoid excessive chilling of the frozen material additional measures, such as an insulating wall between the refrigerant and the material, have to be taken to provide correct temperature control. In particular, however, there is also the fact that here the transformation respectively takes place into the gaseous phase, so that comparatively large volumes of gas occur and have to be discharged to the outside. In confined spaces, this leads to problems, which for example makes it more difficult for a corresponding transport container to be transported in an aircraft.
The invention is based on the object of providing a comparatively small and lightweight, and consequently handy, transport container with which the frozen material is reliably kept at the intended chilling temperature in a simple way during a predetermined transporting period, without gases thereby being released and without measures for preventing excessive chilling of the material being required.
This object is achieved according to the invention by providing at least one chilling chamber for the material and at least one refrigerant chamber which is separate from the chilling chamber, contains the refrigerant and is permanently hermetically sealed, by providing a refrigerant with a solid/liquid phase transition in the temperature range from −15° to −100° C. and by the insulation being a superinsulation with a coefficient of thermal conductivity λ of ≦0.01 W/m K.
Mercury or organic substances or mixtures for which the phase transformation temperature preferably lies between −30° and −85° C. come into consideration as refrigerants. Solidified mercury has a melting point of about −39° C. (at atmospheric pressure). This temperature is very suitable for keeping biological material chilled, such as tissue samples or cell cultures that are for example being sent for the analysis of proteins and RNA to diagnose medical conditions (cancer) and precludes damage caused by excessive chilling. A further advantage is that, when the refrigerant is used, neither gas nor vapor occurs and there is virtually no change in volume during the phase transformation.
In the case of the transport container according to the invention, the refrigerant remains inaccessible in the housing of the refrigerant chamber or in the inner container. The mercury that has liquefied (been used) after transport can be reconditioned by means of a phase transformation back from liquid→solid for a new refrigerated transporting operation, by freezing the removable refrigerant container or inner container, for example by immersion in liquid nitrogen.
Expedient refinements and developments of the transport container according to the invention are provided by the subclaims. These are also directed at particularly simple production and handling of the transport container and at adaptation of the chilling capacity to the transporting distance to be covered, and consequently the chilling period.
Exemplary embodiments of the transport container according to the invention are explained in more detail below on the basis of a schematic drawing, in which:
The transport container 1 according to
The insulation 6 and the insulating closure 8 consist of a high-grade thermal insulating material with a very low coefficient of thermal conductivity λ of, for example, 0.002 W/m K. This known thermal insulating material is also referred to as superinsulation because of the outstanding insulating effect.
The inner container 2 is represented in
The conical stopper 34 may be appropriately fitted with a press fit, in that it is shrunk before fitting by intense supercooling. An annular seal 36 of amalgam-forming metal, such as for example copper, may also be optionally fitted at the same time. This is accompanied by formation of an amalgam (Hg—Cu alloy), and it may be possible to dispense with welding closure by means of the welding bead 37.
This additional container 37 also has a a refrigerant chamber 38 filled with refrigerant 38′, a formation corresponding to
The additional container 37 has on its upper end face a central, short threaded stub 39, which fits into a central, internally threaded bore 40 on the underside of the inner container 30. Therefore, the additional container 37 can be firmly connected to the inner container 30 and close contact between the containers 30 and 37 can be thereby achieved, which ensures a good heat transfer.
A further additional container 37 can be connected to the inner container 30 in a corresponding way at the top. The internal thread 41 on the upper edge of the chilling chamber 31 serves for this purpose. This is given such an axial length that a screw stopper 42 for closing the chilling chamber 31 can be screwed in by means of a hexagon socket wrench to such an extent that the threaded stub 39 of the additional container 37 can also be screwed into the upper end of the internal thread 40.
An additional safeguard against escape of refrigerant 47′ is achieved by providing a cover ring 49, which covers over the outer ring of refrigerant chambers 46 and is firmly welded to the cylinder block 45, as
The cover ring 49 has an internal thread 50, in which a disk-shaped screw stopper 51 is screwed with its external thread 52, terminating flush with the cover ring 49 on the top side. The screw stopper 51, which terminates the chilling chambers 46, has on its upper side two pairs of diametrically opposed bore holes 53, offset by 90° in relation to one another, for placing a pin wrench when screwing in or unscrewing. The cover ring 49 has two diametrically opposed grooves 54, which form two parallel flats for placing a wrench, in order that a high screwing force can be applied to the screw stopper 51.
The cylinder block 56 is provided at the top with a central threaded stud 59 for connection to the inner container 44 according to
The stopper 62 with the coating 64 is then fitted into the filling opening 33, expediently by means of heat shrinkage, so that it is held in the filling opening 33 with a press fit. With preference, two fitting variants come into consideration for this: according to
By the alternative according to
The inner container 70 according to
The special feature of the inner container 70 is that it has a jacket chamber 78, which encloses the wall 76 and contains a refrigerant 78′ melting at a higher temperature in comparison with the refrigerant 71′, with a melting point in the range from 0° to −15° C., and is enclosed by a jacket wall 79. An insulating jacket 80 with an outer container wall 81 encloses the jacket chamber 78. The insulating jacket 80, once again configured as superinsulation, is formed in two parts with a cup-shaped bottom jacket part 82 and a conversely cup-shaped cover jacket part 83, so that the cover jacket part 83 can be removed in order to make the cover 77, and consequently the chilling chamber 74, accessible. In the position for use (shipping position) shown in
The use of two different refrigerants 71′ and 78′, envisaged according to
The transport container 1 is used for example to transport one or more frozen tissue samples from one location to another location at which there are respectively stationary chilling devices for freezing. The shipping operation is therefore an intermediate link in a chilling chain. The shipping may be performed for example by means of courier services, which ensure transportation even to remote locations of the world within a comparatively short time of 1, 2 or 3 days. To be specific, the following procedure is followed here:
The sender first provides freezing of the inner container 2, 30, 44, 70 and the additional containers 3, 4, 37, 55 with liquid nitrogen involving complete solidification of the refrigerant filling 15′, 24′, 32′, 38′, 47′, 57′, 71′, 78′. Then, the sample 17 placed in the sample container 18 is inserted into the chilling chamber 16, 31, 46, 74 and the latter is closed with the screw cover 14, 77 or the screw stopper 42, 51. The inner container 2, 30, 44, 70, and if appropriate the additional containers 3, 4; 37, 55, are then placed in the insulation 6, in the case of the inner container 30, 44 the additional containers 37, 55 first being firmly screwed with the inner container 30, 44 if they are required for an increased chilling capacity, for example over a long transporting distance. After that, the insulating cover 8 is placed on and the screw cover 11 is firmly screwed on, whereupon the transport container 1 is shipped with as little delay as possible.
The recipient opens the transport container 1 and removes the sample container 18 with the sample 17 in the reverse sequence. The temperature in the insulating chamber 5 of the insulation 6 or in the chilling chamber 16, 31, 46, 74, which must for example lie around −40° C. to correspond to the melting point of the refrigerant, is expediently measured by the recipient when the transport container 1 is opened. If it is not at this temperature, it is established that the chilling capacity of the refrigerant filling 15′, 24′, 32′, 38′, 47′, 57′, 71′, 78′ has not been adequate because the transporting time has been grossly exceeded, so that the sample 17 may possibly have become damaged and must then be rejected.
A transport container 1 provided with a 5 cm thick superinsulation in accordance with the above specifications has, for example, an outside diameter of 24 cm and a length of 24 cm and is consequently handy and ideally suited for shipping by courier.