MX2008010535A - Liquid container with extraction chimney - Google Patents

Abstract

The invention relates to a liquid container (1) with an upper opening (11), and a tube-shaped extraction chimney (17) which extends through the opening (11) into the container , incorporating in its lower end region a liquid-permeable zone in the form of a finely-porous, flow-resistant element (27), so that liquid exchange can take place between the escape chimney (17) and the container interior (37) surrounding it by way of the flow-resistant element (27). A further aspect of the invention is the venting groove formed by a radial recess (47), in the upper region of the outer wall (49) of the escape chimney, which ensures adequate venting of the space (47) above the liquid surface (41).

Description

LIQUID CONTAINER WITH EXTRACTION CHIMNEY DESCRIPTION OF THE INVENTION The invention relates to a liquid container with an upper opening and a tube-like extraction chimney that extends into a container and is flush with the upper opening and which it has a liquid permeable zone in its lower end region near the bottom of the container. The invention in particular relates to containers that are used as liquid reservoirs in automated analyzers. When used in said automated analyzer, reactive liquid is removed from the liquid containers by means of automatic pipettors. In modern systems this takes place in a rapid cycle in order to allow a high processing capacity of respective analytical processes. In this process the liquid container is rapidly transferred to the pipetting station by means of a transport device, for example in the form of a rotor and stops there, whereby the automatic pipette or the suction needle is immersed within the extraction chimney through the upper opening of the liquid container in order to remove liquid by suction. In the case of automated analyzers with a high treatment capacity, only extremely short cycle times of a few seconds are available for each Ref .: 195225 individual pipetting process including the location in the liquid container in the pipetting area. The problem associated with this is that when the liquid container stops abruptly in the pipetting zone, the liquid in the container is agitated and can splash in such a way that a reasonably even liquid level does not occur frequently until after a certain time. Particular waiting time which takes more time than the short pipetting cycle time required for the high processing capacity operation. Usually pipetting should be avoided when the level of the liquid in the extraction chimney still fluctuates because the tip of the pipette would be wet on the outside with liquid over a relatively large area in an unwanted form and therefore a carryover volume The relatively large amount of liquid would adhere to the outside of the pipette tip when the pipette is withdrawn from the liquid container and then causes contamination in subsequent pipetting operations. In order to avoid this the tip of the pipette should also be slightly submerged within the liquid to be pipetted during pipetting and the filling level in the liquid container should, if possible, be at rest. Likewise, the pipette should be prevented from drawing in air due to a fluctuating liquid level. In addition, the formation of foam in the extraction chimney must be eliminated. In the case of liquid containers previously of the type under consideration herein, this requirement would normally only be met within the cycle times that would take a long time for a high throughput operation in automated analyzers. Reference can be made for example to WO 97/12677, US 5,102,631 or DE 38 38 278 Cl with respect to prior art reaction liquid containers with an extraction chimney. In the liquid container of WO 97/12677 Al the upper end of the tube-shaped extraction chimney is provided with a flange projecting radially outwardly with which it is supported in a form hung over a mouth of the opening of the tube. container. The completely open lower end of the extraction chimney extends into the vicinity of the bottom of the liquid container such that liquid communication can occur through the lower opening of the extraction chimney between the extraction chimney and the exhaust chimney. region of the surrounding interior space of the liquid container. In order to allow pressure between the interior space of the container and the environment to equalize during pipetting, reductions are provided in similar to slots in the wall thickness in the upper region of the extraction chimney which would allow the air flow between the opening of the liquid container and the tubing of the extraction chimney. An exemplary embodiment of a DE 38 38 278 Cl container has an extraction chimney whose cross section is substantially smaller than the cross section of the upper opening of the container and this extraction chimney pierces a screw cap screwed over the opening mouth and joins this cover. A through hole in the threaded cap allows a pressure equalization between the internal space of the container and the external environment. The extraction chimney reaches the bottom vicinity of the container in such a way that exchange of liquid between the extraction chimney and the surrounding internal space of the container through the lower side of the extraction chimney opening can occur. In an example of additional embodiment of DE 38 38 278 Cl the external circumference of the upper end of the extraction chimney and the internal circumference of the mouth surrounding the upper end of the extraction chimney are only slightly different in such a way that there is no remaining a ventilation path of sufficient magnitude for the equalization of pressure between the interior of the container and the environment between the external side of the extraction chimney and the internal surface of the mouth. A through hole in the chimney of the extraction chimney is provided at its upper end for pressure equalization. The lower end of the Extraction chimney is essentially completely open and spacer bars are provided at the lower end of the extraction chimney. The known liquid container of US 5, 102631 is constructed in a manner similar to the last example of the mentioned embodiment of DE 38 38 278 Cl and therefore also has a through hole in the tubing of the extraction chimney at its upper end. The extraction chimney extends to the bottom of the liquid container but large lateral openings are provided in the extraction chimney tubing at its lower end. The inventor's experiments in prior art liquid containers constructed as disclosed above confirmed that when the container is quickly placed in a treatment zone the liquid in the container is agitated, splashed and can foam in the container and the level is calm and Equalization does not occur in the extraction chimney until after a period that is not tolerable for analyzers of high treatment capacity. The object of the invention is to improve a liquid container of the type mentioned above in such a way that it can be used in automated pipetting systems in a high processing capacity operation. In order to achieve this object it is proposed according to the invention that the liquid permeable zone of the extraction chimney has at least one finely porous flow resistance element in such a way that the exchange of liquid between the extraction chimney and the internal space of the container surrounding it in the region of the liquid permeable zone can only be take place by means of a respective element of resistance to flow. The flow resistance element serves as a flow brake which ensures that when the liquid container abruptly brakes, the initial stirring movements of the liquid around the extraction chimney are damped considerably and manifest themselves in a delayed manner as Slow changes in the level in the extraction chimney. Therefore, the flow resistance element forms a "slow step" for the liquid in the extraction chimney with respect to the frequency and severity of the stirring movements and swings of the liquid level. When the liquid container is quickly placed in a pipetting station, for example, by means of a carousel or rotor carrying the container, only relatively slow changes occur at the level of the extraction chimney regardless of the shaking movements around the container. the extraction chimney driven by the stopping of the container. Therefore, the pipetting tip of such automated pipetting device can be admitted into the extraction chimney immediately after the container has stopped and submerged into the liquid to the lowest possible depth in order to pipette. The depth of immersion of the level of the liquid in the extraction chimney is usually detected by sensory means, for example, by means of capacitive sensors in the case of automated pipetting stations and the immersion depth is controlled according to the sensor information . This can be carried out in a corresponding manner also when a liquid container according to the invention is used. As desired, the pipetting tip only gets wet on its outer side with the liquid in a short length in such a way that only a small volume of liquid entrainment can be collected on the outside of the pipette. Surprisingly, rapid changes in the level of the liquid in the extraction chimney due to the effect of external agitation are not expected during short pipetting times due to the slow step effect of the flow resistance element. Therefore the level of the liquid in the extraction chimney at most only varies slowly and to a degree deadening in such a way that the automatic pipetting device can reliably pipette from the respective calculated fill level in the extraction chimney with a low depth of Dip the tip of the pipette. In addition, the flow resistance element can designed in such a way as to act as a brake for the foam which substantially prevents the passage of foam from the internal space of the container into the extraction chimney. The flow resistance element is preferably formed of a fleece material, in particular felt or / and a fabric or / and a sintered plastic material, in particular polyethylene or polypropylene or / and an open pore foam. According to a preferred embodiment of the invention, the lower end of the extraction chimney has a tube opening at the front end which, however, is filled with the flow resistance element. In this connection, a further development of the invention provides that the flow resistance element projects downwards from the lower opening of the front end of the extraction chimney and can therefore serve as a spacer element between the bottom of the container and the opening of the front end of the extraction chimney. Said solution can for example be achieved with a flow resistance element in the form of a filter element made of sintered polyethylene which is inserted and secured in position in the lower opening of the extraction chimney. In accordance with one embodiment of the invention, Flow resistance element is a fine pore reticular mesh made of metal or plastic. Alternatively or 'in addition the extraction chimney can be provided with a plurality of capillary through holes at its lower end and the area of the extraction chimney which is finely drilled in this way forms the flow resistance element. With the various possibilities of making an element of resistance to flow, care must always be taken to provide the desired flow brake property and the agitation movements of the liquid can only result in comparatively slow and muted changes in the chimney level. of extraction. The extraction chimney is preferably an elaborate component of plastic which, when preparing the liquid container, can be inserted into the liquid container through its opening. As is known, it is proposed that the upper opening of the container has a mouth which projects upwards and in particular a threaded cap mouth whose internal surface forms the circumferential boundary surface of the container opening. The upper end of the extraction chimney may have a flange section which is attached to a protruding face of the mouth facing upwards. The extraction chimney can therefore hold in a stable form in its mounting position in the container. A further aspect of the invention is the provision of a liquid container of the aforementioned type in which the tubing of the extraction chimney in the region of its upper end is closely adjacent radially and opposite the circumferential boundary surface of the The opening of the container and the lower end region of the extraction chimney near the bottom of the container has a liquid permeable zone where in the area of its upper end the wall of the tubing of the extraction chimney is formed in zones of such form that said area on the outer side of the tubing of the extraction chimney is at a greater distance from the circumferential boundary surface of the opening of the vessel in order to provide a venting path in particular in the form of a vent slot formed by a recess radial in its tubing wall which extends axially and downward beyond the surface area e circumferential boundary of the container opening. This venting path allows rapid and effective pressure equalization between the interior of the liquid container and the environment and can be manufactured in a simple manner. In this connection, the through holes in the extraction chimney tubing can be omitted. venting purposes. In the case of prior art liquid containers said through holes require a limitation of the maximum liquid level if it is intended to prevent agitated liquid from entering through the through opening into the upper region of the extraction chimney. It should be noted that the appearance of the venting path is also independently significant and therefore can also be used for extraction chimneys that are not equipped with a flow resistance element of the above-mentioned type but rather, for example, with a space of the conventional type. The invention will be further explained with reference to the figures. Figure 1 shows in a sectional side view an embodiment example of a liquid container according to the invention with an extraction chimney and a flow resistance element in the lower opening of the extraction chimney. Figure 2 shows the extraction chimney of figure 1 separately in a perspective view. Figure 3 shows another embodiment of an extraction chimney for a liquid container according to the invention in a perspective view. In Figure 1 an example of embodiment of a liquid container 1 according to the invention is shown in a longitudinal section along a vertical central plane. The liquid container 1 is a bottle with a screw cap 3. The neck of the bottle 5 is a threaded cap mouth with an external thread 7 which serves as a thread for the threaded cap 9. The beak-like bottle neck 5 has the withdrawal opening 11 of the liquid container 1 and has a shoulder with a ring shoulder 15 extending radially inwardly on its inner surface 13 on which an extraction chimney hangs. with an upper end flange 19. In Figure 2 the extraction chimney 17 is shown separately in a perspective view. In this example it comprises, with respect to its basic form, a hollow cylindrical tube body 21 which has openings 23, 25 at its front ends. The lower tube opening 25 of the tube body 21 is filled with a finely porous flow resistance element 27 which is a liquid permeable plug made of sintered polyethylene. However, other materials can also be used to form the flow resistance element 27, for example, felt, fabric or open pore foam. In the example according to FIG. 1 and FIG. 2, the flow resistance element 27 projects downwards below with the lower edge of the tube body 21 in such a way that it can serve as a spacer element. This function is not used in the case of the liquid container in figure 1 because the extraction chimney 17 hangs in the liquid container 1 in such a way that the lower end 29 is at a distance, but also a small distance, from the bottom 31 of the container liquid 1. The extraction chimney 17 according to figure 1 can, however, due to the spreader function of the flow resistance element 27 also be used in the liquid container in which it is kept at the bottom of the container. According to FIG. 1, the extraction chimney 17 is immersed in the interior of the container 33 down to near the bottom of the container 31 in the embodiment example shown in such a way that the liquid communication between the internal space 35 of the chimney of extraction 17 and the surrounding annular space 37 inside the container 1 can only take place through the finely porous flow resistance element 27. In Fig. 1 the liquid container 1 is shown in its idle state in which the level of liquid 39 indicated schematically in the extraction chimney 17 corresponds to the level of liquid 41 in the space of the remaining vessel 37. In acceleration and deceleration processes such as those that occur when the liquid container is further transported and abruptly placed in a pipetting station, the liquid 43, however, is set in motion in such a manner that it has a tendency to agitate, splash and perhaps foam. This tendency is much greater in the area of larger annular space 37 of the container 1 than in the extraction chimney 17 with its considerably smaller volume. The flow resistance element 27 ensures that the vigorous movements of the liquid in the annular space 37 are not transferred directly to the liquid in the extraction chimney but rather in a damped and delayed form such that the level 39 only varies relatively in a slow manner even after rapid placement of the liquid container 1 in a pipetting station. This can be taken into account in the control of the pipetting process that then takes place. The pipetting process can then be carried out in such a way that the pipetting tip (not shown) descending through the opening of the container 11 into the extraction chimney 17 after removing the cover 9 is only immersed in a small magnitude within the liquid 43. The pipetting of the quenched liquid 43 in the extraction chimney can then take place in a very short cycle time of for example less than three or even less than two seconds.

In rapid pipetting operations there is, in addition to the calm of the liquid level 39 in the chimney extraction 17, still an additional problem. This additional problem relates to the venting of the space area 45 above the level of the liquid 41 during pipetting. The inventor's previous experiments with extraction chimney constructions known from the prior art and which have been mentioned above have shown that the venting channels that are possible with these chimneys are too small to allow a sufficiently rapid pressure equalization between the external space of the container and the spatial area 45 in a high processing capacity operation. Adequate rapid venting would be achieved with a variant of the extraction chimney in which a very large window would be provided in the extraction chimney above the liquid level 41. However, said solution must be avoided in accordance with the invention because said window in the upper area of the container requires space and therefore limits the maximum filling level of the liquid container. In addition, there is a risk that the liquid 43 may be agitated from the annular space 37 in the interior space of the extraction chimney 17 through the window in such a way that there is a risk that the pipetting tip introduced into the chimney of extraction 17 during the pipetting operation get wet over a larger area when the liquid is agitated. In accordance with an aspect of the invention which is regardless of importance and therefore can also be used in extraction chimney without a flow resistance element of the aforementioned type, the extraction chimney 17 has a vent slot 51 formed by a radial recess 47 in its casing wall 49 in the region of its upper end extending downwardly and axially beyond the region of the circumferential boundary surface 13 of the opening of the container 11, i.e., beyond the region of the mouth 5 such that it can provide a vent trajectory sufficiently large and long along the inside of the mouth 13. Such radial recess 47 of the tubing wall 49 of the extraction chimney 17 can be manufactured in a simple form. In particular, but not preferably, several such venting slots 51 formed by the radial recesses may be provided. In the terminology used here, radial recess means that the tubing wall 49 in the region of the vent slot simply does not have a reduced thickness but rather the shape of the wall of the tubing observed in cross section describes a radial recess projecting towards inside. In this way the vent slot can be designed to be comparatively large without impairing the stability of the extraction chimney. However, in order to form a venting path, for example, it can also be envisaged that the casing wall 49 has a rope path in a particular area having an enlarged spacing with the circumferential boundary surface 13 of the container opening 11. Therefore, in the vent design described above it is not necessary to drill the upper region of the wall pipe 49 of the extraction chimney 17 with vent windows. Therefore, the maximum level of liquid filling in the liquid container according to the invention is not limited by venting measures. Also, no liquid can reach the internal space 35 of the extraction chimney 17 from the annular space 37 in the upper region of the extraction chimney 17. Experiments have shown that the tendency of the liquid in the container to splash or move through can be counteracted. the venting slot when the container is accelerated by means of an optimal orientation of the venting slot 51 in the container 1 in relation to its walls and taking into consideration the states of movement of the container. Figure 3 shows a modified embodiment of the extraction chimney 17 of Figure 1. The tubular body 21 of the extraction chimney in Figure 3 has a smaller external diameter than the tubular body in Figure 1. This is compensated by extending axially spacer ribs 53 on the outside of the cylindrical tubing wall in the upper region of the extraction chimney 17 in Figure 3 that in the state mounted on the liquid container are opposite and close to the internal surface of the threaded cap mouth and therefore ensure that the extraction chimney is maintained in a more stable manner. The pipetting operations with the liquid container according to the invention usually take place with the closure cap 9 removed. Especially for pipetting operations that can be performed slowly, the closure cap 9 has a guide funnel 55 which, when the closure cap 9 is mounted, can be pierced by the tip of the pipette upon entering the container 1. The container of compliance with figure 1 it can optionally be accommodated together with additional containers in a common handling cassette (not shown) in which it can pass through several stations in an automated analyzer. In a variant of the embodiment example shown, a container according to the invention can also be designed as a two-chamber container or a multi-chamber container with several extraction chimneys of the aforementioned type. It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Claims (10)

1. . CLAIMS Having described the invention as above, the content of the following claims is claimed as property: 1. A liquid container with an upper opening and with a tube-like extraction chimney extending into the container and flush with the opening and having a liquid permeable zone in its lower end region near the bottom of the container, characterized in that the liquid permeable zone has at least one finely porous flow resistance element such that liquid exchange between the extraction chimney and the internal space of the container that surrounds it in the region of the liquid permeable zone can only take place by means of a respective flow resistance element. The liquid container according to claim 1, characterized in that the flow resistance element is formed from a fleece material, in particular felt or / and a fabric or / and a sintered plastic material, in particular polyethylene or polypropylene or / and an open pore foam. 3. The liquid container in accordance with claim 1, characterized in that the flow resistance element is a fine pore mesh network or a lower wall section of the extraction chimney with a plurality of capillary through holes. The liquid container according to any of the preceding claims, characterized in that the extraction chimney has an opening at its lower front end which is filled with a flow resistance element. The liquid container according to claim 4, characterized in that the flow resistance element projects downwards out of the opening of the extraction chimney. 6. The liquid container according to any of the preceding claims, characterized in that the extraction chimney comprises a tube element that can be inserted into the liquid container through its opening. 7. A liquid container with an upper opening and with a tube-shaped extraction chimney extending within the container and flush with the opening, the outer circumference of which in the region of its upper end is radially adjacent in a manner that near and opposite the circumferential boundary surface of the container opening and the lower end region near from the bottom of the container has a liquid-permeable zone in particular according to one of the preceding claims, characterized in that in the region of its upper end the tubing wall of the extraction chimney is formed in zones such that the area of the external side of the tubing of the extraction chimney is at a greater distance from the circumferential boundary surface of the opening of the vessel in order to provide a venting path in particular in the form of a vent slot formed by a radial recess in its tubing wall which extends axially and downwardly beyond the area of the circumferential boundary surface of the container opening. The liquid container according to any of the preceding claims, characterized in that the upper container opening has a mouth projecting upwards and in particular a threaded cap mouth whose internal surface forms the circumferential boundary surface of the opening of the container. container. The liquid container according to claim 8, characterized in that the upper end of the extraction chimney can have a flange section with which it joins a protruding face facing upwards from the mouth. 10. The liquid container in accordance with claim 9, characterized in that the shoulder surface of the mouth facing upwards is formed by means of a step on the inner surface of the mouth.