EP0345527A2 - Auxiliary suction device for taking liquids from deep voluminous vessels - Google Patents

Abstract

For taking liquids from deep voluminous vessels by aspiration containers with short suction pieces, a metered intermediate volume of liquid, accessible from above, is aspirated from a liquid volume of changing depth in the vessel. Simultaneously with this aspiration, a defined sample of liquid is sucked off. This suction aid possesses a tube which can be introduced into the vessel and a non-return valve closing towards the lower tube end. This tube (5) is arranged on a dish (2) which can be placed upon the mouth (6) of the vessel. Preferably, the dish (2) is part of a housing (1) in which the upper opening (16) of the tube (5) is arranged close to the cover wall (12) and, in the upper part of the dish (2), above the intermediate volume of the liquid held at least in the dish (2), there is an inlet opening (13) for the tip (14) of a working vessel (15) provided with a piston. With each sampling, an intermediate volume of defined depth is always produced in the housing. <IMAGE>

Description

The invention relates to a method for withdrawing liquid from large-volume, deep vessels through suction vessels with suction pieces that are short in relation to the deep vessels, through which suction takes place, suction being carried out in the vessel from a liquid volume that changes in depth.

Furthermore, the invention relates to a device for performing the method as a suction aid for large-volume, deep vessels, with a tube that can be inserted into the tube and a check valve assigned to the tube cross-section, which closes to the lower tube mouth, and a shell detachably fitted onto the tube, into which the Pipe with the check valve opens.

From DE PS 29 26 691 a repeating pipette is known, on which a syringe-like vessel is to be arranged, which has a cylinder body and a conical tip at one end.

A piston can be moved back and forth in the cylinder body, so that liquids can be drawn in when the piston is retracted and dispensed when the piston is advanced. The piston expediently has a conical approach to reduce the air volume, which protrudes into the conical tip. The conical tip is dimensioned both in length and in the design of the outer shape. The arrangement on a repeater pipette is used in the laboratory to draw in liquids and dispense them in doses.

Such syringe-like suction vessels can be used in many ways, but problems arise when liquids are to be removed from a larger bottle, ie from a deep vessel, because the tip reaches the liquid while the bottle is still filled, but during the process with increasing removal of liquid no longer immersed in it.

Accordingly, it is known from DE PS 32 04 178 to take special precautions for a favorable operation for the metered dispensing of small amounts of liquid on a pipetting device as a holding mechanism for a detachably used syringe. But even here, the syringe has only a relatively short, in particular dispensing tip, which is subject to the above considerations.

In this respect, problems arise in the use of the repeating pipette or pipette device mentioned when liquids are removed from storage vessels in laboratory operation.

These are organic and inorganic liquids, solvents, acids, alkalis and reagents, with handling in the ml order being intended for determining an order of magnitude.

The latter is not to be interpreted restrictively, because other dimensions can also be handled when adapting dimensions.

From EPA 0 212 964 a sampling tube with a non-return valve is known which can be inserted into a vessel in order to remove liquid when a suction force is applied at the upper end. An attachment piece is also provided as a valve body at the upper end of the tube. This is connected to the interior of the pipe by a constricted channel and has a small valve body in a chamber with through openings, which, however, does not need to be closed with absolute certainty because a liquid level in the pipe is to be maintained by the surface tension of the liquids. This already limits the application to certain liquids.

The purpose of this known embodiment is, in a simple embodiment, the valve body part, which is connected to the tube by a plug connection, once discard use, while the pipe, which is intended as a special component in this version, can be washed out and reused. This tube is made of glass. It is therefore not easy to cut to size. In addition, this tube is only used for taking samples by applying a suction force, which precludes the use of syringe-like suction vessels because there is an empty, in particular undefined space above the valve.

In laboratory operation, the problem arises from the above-mentioned points of view that a quantity of liquid can always be drawn uniformly from supplies with a changing liquid level due to increasing withdrawal by suction. So-called bottle dispensers are known, which represent operational devices of considerable size, work with pump systems and, above all, convey them into an open additional vessel from which liquid can then be removed. In this respect there is an indirect removal of liquid from a vessel, but also due to the known transitions into the additional vessel with considerable air inclusion and evaporation effects. Handling is cumbersome. The known dispensers are complex and very expensive.

Other known devices use a receptacle or device vessel which is compressible in order to either squirt out a quantity of liquid which is barely precisely definable by squeezing it or to take it up into a storage space which can be changed in its capacity by a further, arbitrary control . This does not allow an accuracy for a liquid reach removal, as intended for the invention. The invention always starts from the use of syringe-like suction vessels, which are known as pipettes.

The invention is therefore based on the object of providing a method and a device of the type specified at the outset, which in particular also using the syringe-like suction vessels with repeating pipettes or pipetting devices of the type specified above in direct operation while avoiding complex refilling into short storage vessels, which in particular problematic in the treatment of aggressive substances, enable consistent handling while maintaining the same suction conditions.

This object is achieved by the method in that an aspirated intermediate volume of the liquid which is accessible from above is simultaneously aspirated with this aspiration and that a defined liquid sample is aspirated at the same time with this aspiration, the metered intermediate volume being kept ready or refilled as a reservoir outside the deep vessel becomes. In this case, a minimum amount is advantageously first sucked in by a first suction at least in preparation for the intermediate volume and in the next suction step both the intermediate volume defined in depth is produced and a metered amount of liquid is sucked out of the intermediate volume and at the same time the metered intermediate volume of the liquid is refilled.

There is a twofold step at the beginning of the liquid withdrawal. In one embodiment, namely when only one bowl is arranged, an intermediate volume can be formed by feeding back the amount that was sucked in first.

In another particularly advantageous embodiment of the method, in particular when the metered intermediate volume is advantageously produced with a defined liquid depth, a minimum amount is first sucked in by a first suction, at least in preparation for the intermediate volume, and also in depth in the next suction step defined intermediate volume. A further advantageous embodiment is that the intermediate volume mentioned is in each case produced with a defined liquid depth and a defined liquid sample is drawn off from the metered liquid volume.

However, this then enables the metered liquid volume of a defined liquid depth to be maintained in only one process step at a time when a sample quantity is taken. In an advantageous embodiment, the minimum amount, at least for the preparation of the intermediate volume, does not exclude the fact that even with the first suction, the intermediate volume is produced with a defined liquid depth.

When using particularly small-volume syringes, a larger-volume syringe can be used once for the safe filling of the suction aid.

In the preferred embodiment, the invention creates a two-stage level through the use of an operationally metered suction force, in that a metered amount is always made available for the subsequent removal from the changing liquid volume in the vessel, and this provision is made automatically with a removal for the next removal. This enables the use of the devices mentioned without considerable effort.

This solution creates a process with two result stages in one process step by going through in one stage the suction effect of the syringe-like suction vessels is produced from a changing volume, the defined intermediate volume, from which a sample can be reliably taken in the other stage, even with short syringes.

In a simple embodiment, the device of the type specified at the outset is that this tube is arranged on a shell which can be placed on the mouth of the vessel, from which the tube emerges at the bottom and in which the tube has an upper opening. An intermediate volume is created above the check valve. This intermediate volume can extend into the shell. This bowl can therefore be the basis for the intermediate volume of the liquid with a defined level in preparation for the next suction process.

The characteristic features are that a receptacle for an intermediate volume is formed above the check valve, which is larger than a volume to be aspirated, and that an inlet opening is provided above the check valve for the tip of a working vessel provided with a piston, with a sealed insert the tip is provided in the inlet opening.

In this respect it can be seen that the shell is a simple design. It is particularly preferred, however, that the shell is part of a housing in which the upper opening of the tube is arranged near the top wall, and that an intermediate volume of a defined depth can be produced in the space between the inlet opening and the check valve and in that A vent valve is arranged at the top of the housing.

In such an embodiment of a housing, the inlet opening is provided for the tip of a suction vessel provided with a piston. This inlet opening is in the top wall of the housing. This is an advantageous feature for the formation of the inlet opening as an abutment for the tip of the syringe-like suction vessel.

Surprisingly, this also creates a simple device which, in the two-step method mentioned, creates a defined volume for a specific immersion depth of the tip from an undefined volume in the same process step with the suction. If only one bowl that is open at the top is used, this can have a certain depth for the intermediate volume. A deficiency lies in the exposed evaporation surface and possible contamination, which can be disadvantageous for certain liquids.

The housing-like design has the advantage that the vessel, in particular the bottle, and the intermediate storage in the form of the intermediate volume are kept largely sealed and are protected against evaporation and contamination. It is expediently included here that an upper level is provided for the intermediate volume, which is in the housing within the upper housing part, i.e. is arranged above the lower housing shell.

It is possible to arrange the check valve at the bottom of the tube, so that the contents of the tube are closed at the bottom when the suction is removed. However, it is preferred that the check valve is arranged at the top below the upper opening of the tube. This will not only cause reflux hindered from the removal chamber of the housing, but at the same time also the outflow from the pipe, because any air entry from above is excluded. In this respect, the check valve is designed differently from the known design specified in the introduction, because it ensures a secure closure, in particular in the form of a ball valve. It goes without saying that the parts of the device, in particular the valve, consist of a material with chemical resistance to the substances to be processed.

In the first suction step, the liquid should be sucked in at least via the check valve in order to obtain a supply. When the check valve is arranged at the bottom of the tube, it is included that the tube is practically filled with it. When the check valve is arranged at the top of the tube, it is included that a tube section or a valve chamber above the valve body is advantageously also filled with liquid.

The valve arrangement above has the advantage that the tube can consist of a material that can be cut off. This makes it possible to adapt the suction aid to a depth of the vessel or a bottle.

The shell or the housing and the tube can be made in one piece. The result is a device that can be placed on a vessel, in particular a bottle. From this point of view, too, there is an advantageous embodiment in that in the shell-like lower part of the housing there is provided a tubular extension running in the direction of the central axis of the shell, which has the check valve at the top and in which the tube is inserted in a sealed manner from the bottom. This has come from in particular positional advantages, in which case the adaptable tube can be used. The seals can be created by inwardly directed projections in the attachment or a fit is provided which ensures tightness, a weakly conical design also being possible.

If an intermediate volume is addressed above, each of which reaches a certain level during each suction process, then a particularly preferred embodiment is that the inlet opening forms an abutment for the tip of the syringe-like working or suction vessel for a defined insertion depth for the tip, that the mouth reaches below a minimum fill level. The extent of the mouth below the minimum fill level must be so large that the entire suction volume can be extracted without the tip mouth being released from the liquid.

Such an abutment can be designed in various ways. A conical design of the inlet opening corresponding to the conical shape of the tip of the syringe-like suction vessel is preferred.

The syringe-shaped working vessel preferably has a suction volume which corresponds at least to the receiving volume of the tube and preferably to the intermediate volume. The process is at least ensured when a minimum fill level is reached, into which the tip of a suction vessel can plunge sufficiently deep during the next process.

It goes without saying, according to the above remarks, that the suction volume of the suction vessel in one stroke is sufficient to begin with the preparation for the intermediate volume to create the check valve according to the above statements. This is particularly important if the depth of the large-volume vessel can be dimensioned as desired, so that there is no direct dependence between the suction volume and this depth. It is important to prepare for the intermediate volume, although it is not excluded that several strokes of the suction vessel may be necessary at the beginning of the absorption of liquids. This is expressly included.

The suction aid according to the invention as a device, in particular for continuous use in the laboratory, can advantageously also form an evaporation barrier.

From this point of view, the bowl or the bowl-like lower part of the housing is advantageously designed with conical wall parts which form a centering on the bottle mouth, but at the same time also produce a seal by the system lying around the circumference.

The above-mentioned vent valve makes it possible to use the syringe-like suction vessel and to perform sufficient suction at the beginning of a process with several piston strokes if there is a deep container that is only filled in the lower area. In this context, the syringe-like working or suction vessel need not be removed from the inlet opening after each stroke in order to vent the housing through the inlet opening.

In the sense of a sealing of the liquid both in the vessel and for the intermediate volume, in a preferred embodiment, there is an on in the inlet opening leadership of the tip opening and closing when the tip is removed arranged in particular in the form of a star-cut membrane.

Further advantageous features result from further claims.

• Fig. 1 eine Seitenansicht einer bevorzugten Ausführungsform im Schnitt in Verbindung mit einem flaschenförmigen Gefäß;
• Fig. 2 eine der Fig. 1 entsprechende Ansicht, jedoch einer anderen Ausführungsform;
• Fig. 3 eine Draufsicht auf die Eintrittsöffnung mit einem Dichtungselement in schematischer Darstellung;
• Fig. 4 eine Seitenansicht einer weiteren Ausführungsform im Schnitt.

The invention is explained below with reference to exemplary embodiments which are shown in the drawing. The drawing shows:

• Figure 1 is a side view of a preferred embodiment in section in connection with a bottle-shaped vessel.
• FIG. 2 shows a view corresponding to FIG. 1, but of a different embodiment;
• Figure 3 is a plan view of the inlet opening with a sealing element in a schematic representation.
• Fig. 4 is a side view of another embodiment in section.

The device according to the invention has a housing 1, which consists of a lower housing shell 2 and an upper, in particular liquid-tight, flange-mounted housing shell 3. The interior between the two housing shells 2 and 3 forms a removal chamber 4. A tube 5 projects downward from the lower housing shell.

In Fig. 1, the lower housing shell 2 is arranged on the edge 6 of the mouth of a bottle 7. In this bottle is liquid 8 with a level 9, the changes with increasing withdrawal, ie decreases.

The tube 5 extends to the bottom 10 of the bottle 7 and then has circumferentially distributed, upwardly directed incisions 11 or the tube 5 is made so short that it ends above the bottom 10. The purpose of this arrangement is to remove liquid from the bottle 7 as long as a liquid volume is still present above the base 10.

The housing 1 has an inlet opening 13 in the upper housing shell 3, in particular in the top wall 12 of the housing. Through this, the conical tip of a syringe-like suction vessel 15 can be inserted, which according to the introductory remarks is arranged on a pipette device or a repeating pipette. The inlet opening 13 is correspondingly conical and in this respect forms a sealing cone for the conical tip 14, which can therefore only be used over the area of a certain depth.

The tube 5 can be made in one piece with the lower housing shell. Its mouth 16 is located just below the top wall. This is included and is a special execution.

In the example shown, a tubular extension 17 is formed in the lower housing shell, which extends up to just below the top wall 12 and forms the mouth 16 and emerges downward from the bottom 18 of the housing shell 2 and has inwardly directed sealing projections 19. The tube is inserted in a liquid-tight manner in this tubular extension 17. Its depth of use can be set within limits, depending on how far the tube 5 is inserted into the tubular extension 17.

The tubular extension has an inward, upwardly concave shell-like profile 20 with a central passage 21 under the upper mouth 16. The upper side forms a valve seat 22 for a spherical valve body 23, which seals the interior of the tube 5 when one is down directed suction force or a pressure force directed from above occurs. A floating out of the valve body 23 from the mouth is prevented by an extension 25 projecting into the mouth 16 on the top wall 12 of the housing. Instead of the extension 25, the top wall 12 can also serve directly as a stop for the valve body 23 in order to hold it in the tubular extension 17 above the valve seat 22.

At the start of a removal process, a vacuum is first created in the suction vessel, which attracts liquid. The valve body lifts from its seat, and the liquid rises through the tube 5 at least up to the valve or the valve body into the bottom shell 2, for example up to a level 24.

Possibly, if the suction vessel is dimensioned, it is initially filled with air. With another dimensioning there is the possibility that this space is filled with liquid through the first suction stroke. In the latter case, the syringe-shaped suction vessel 15 can be removed and the absorbed liquid can then be dispensed. In the former case, at least a second or even several actuation strokes would have to take place in the syringe-shaped suction vessel, the pressure stroke directed into the housing in each case ensuring that the valve body 23 remains in its seat and thus the tube 5 also remains filled. Accordingly, a level 24 is maintained once it is reached. The resulting over pressure in the extraction chamber is relieved by a vent valve 45.

However, the vent valve can be avoided if, after the first suction stroke, the tip 14 or the suction vessel 15 is removed, and then the piston is returned to the tip.

The level 24 is dimensioned with respect to the length of the immersed tip so that the suction vessel can be filled without the level falling below the opening of the tip. The level 24 shows the minimum level. An upper water level is described with reference to FIG. 2 for a closed housing.

In the subsequent processes, the metered suction quantity is then removed from the intermediate container of the housing 1 and the intermediate volume, the immersion depth of the tip mouth 26 being dimensioned such that sufficient liquid can be removed from the reservoir in the base shell 2.

Fig. 2 shows a corresponding embodiment with the same reference numerals, but the valve with the valve body 23 is arranged at the lower end of the tube. Here, the valve body is arranged in an attachment piece 27 which has lateral openings 28 for the entry of the liquid. The attachment piece 27 can be removed, so that the length of the tube 5 can also be adapted to a particular depth of the bottle 7 in this embodiment. It goes without saying that a valve seat for the valve body 23 'is created above the openings 28 by a retraction of the attachment piece, which has enough space within the attachment piece and below the lower tube end to lift off.

In this embodiment, the projection 17 arranged on the lower housing shell 2 is connected to the tube 5 by a close fit. In this context, too, an arched insertion depth for the tube 5 in the shoulder 17 means that it can be adapted to the depth of the bottle.

In Fig. 2, the lower level 24 is shown as the minimum level, but at the same time an upper level 29 below the upper mouth 16 of the tube 5 is indicated, so that the tip 14 always plunge sufficiently deep and shown in Fig. 2 Embodiment can practically see the liquid volume between the level 24 and 29. If the housing or the lower housing shell is narrow, the conical design for the liquid shown in FIG. 2 also applies to FIG. 1.

3 shows a top view of the inlet opening 13. It has a flange-like edge 30 and is penetrated in the interior by a membrane 31 which has star-shaped incisions 32, 33, 34 ... starting from its center. When the tip 14 is pushed in, it passes smoothly in the middle. The tip finds a secure seal in the conical contact area.

When withdrawing, the elastic sectors between the incisions 32 to 34 return to their starting position and essentially close the inlet opening, so that evaporation is largely excluded in this case as well. In addition, it is pointed out that in FIG. 2 the lower valve seat 35 is formed by a constriction of the top piece. Fig. 4 again shows the outer housing shell 2, for example as an open shell or as a part of the vessel acc. Fig. 1. The tube 5 is made in one piece, and it has the valve at the top the valve body 23 according to FIG. 1. The shell-like profile 20 is arranged in the upper tube section.

4, a shell 40 is provided which is open at the top. From it, the downward tube 5 starts. The valve with the valve seat 22 and the spherical valve body 23 is located below the conical or conical wall part 41 of the shell and below its central through opening 37.

In the embodiment shown, the shell has a slightly conical connecting piece 39, which goes down from the through opening 37 and in which the check valve 22, 23 is arranged. The tube 5 is pushed onto this connection piece 39 in a sealing manner.

In the shell 40 and also protruding into the socket 39, an insert 42 which is adapted in shape to the respective wall parts is arranged. It forms a sealing seat for the tip 14 of an intake vessel 15, in which a piston is arranged.

The lower edge 43 of the insert 42 also forms an abutment or a holding element for the valve body 23 if it floats. Its diameter 23 is larger than the passage diameter of the lower edge 43.

This embodiment is also advantageously designed with a shell 40 in which an intermediate volume is formed. With each suction stroke this is lifted up over the check valve.

In use, it is possible to first of all contents of the working vessel after suction into the shell 40 to give, so that an intermediate volume is arranged, in which the tip is then immersed during the next working stroke. The purpose of this is to always create the prerequisites for air-free suction during longer operation.

Claims (12)

1. A method for withdrawing liquid from large-volume, deep vessels through suction vessels with short suction pieces with respect to the deep vessels, through which suction takes place, suction being carried out in the vessel from a liquid volume that changes in depth, characterized in that at the same time with this Suction a dosed intermediate volume of the liquid which is accessible from above is sucked in and that at the same time a defined liquid sample is sucked off with this suction, the dosed intermediate volume being kept available as a supply outside the deep vessel, a first suction sucking in a minimum amount at least in preparation for the intermediate volume is and in the next suction step both the intermediate volume defined in depth is produced and a metered amount of liquid is sucked out of the intermediate volume and at the same time the metered intermediate volume of the liquid is refilled. 2. Apparatus for carrying out the method according to claim 1, as a suction aid for large-volume, deep vessels, with a tube that can be inserted into the tube and a check valve assigned to the tube cross-section, which closes to the lower tube mouth, and a shell detachably fitted onto the tube, into which the tube opens with the check valve, characterized in that a receptacle for an intermediate volume which is larger than a volume to be suctioned is formed above the check valve (22, 23) and that an inlet opening (13; 42, 43) is provided for the tip (14) of a working vessel (15) provided with a piston, a sealed insert of the tip (14) into the inlet opening (13; 42, 43) being provided. 3. Apparatus according to claim 2, characterized in that for the intermediate volume, the shell (2) is part of a housing (1) in which an upper opening (16) of the tube (5) is arranged near the top wall (12), and that an intermediate volume of defined depth can be generated in the space between the inlet opening (13) and the check valve (22, 23), that a vent valve (45) is arranged in the housing (1) at the top. 4. Device according to one of claims 2 and 3, characterized in that the check valve (22, 23) is arranged above below the upper opening (16) of the tube (5). 5. Device according to one of claims 2 and 3, characterized in that the check valve (23 ') is arranged in an attachment piece (27) at the lower end of the tube (5). 6. Device according to one of claims 2 to 4, characterized in that in the shell-like lower part, in particular the housing (1) in the direction of the central axis of the shell (2) extending tubular extension (17) is provided, the top of the check valve ( 22, 23) and in which the tube (5) is inserted in a sealed manner from the underside. 7. Device according to one of claims 2 to 6, characterized in that the inlet opening (13) forms an abutment for the tip (14) of the syringe-like working vessel (15) for a defined insertion depth for the tip (14) in such a way that the mouth (26) is sufficient for the suction volume below a minimum fill level. 8. The device according to claim 7, characterized in that the inlet opening (13) is conical in accordance with the conical shape of the tip (14) of the syringe-like working vessel. 9. Device according to one of claims 2 to 8, characterized in that the syringe-shaped working vessel (15) has a suction volume which corresponds at least to the receiving volume of the tube (5) and the intermediate volume. 10. Device according to one of claims 3 to 9, characterized in that in the inlet opening (13) an opening upon insertion of the tip and upon removal of the tip (14) closing seal is arranged, in particular in the form of a star-shaped incision (32 to 34 ...) membrane (31). 11. The device according to claim 2, characterized in that from the shell (40) the downward tube (5), in which the upward opening check valve (22, 23) is arranged below the shell, and that in the area of Transition between tube and shell a sealing seat for the tip (14) of a working vessel (15) is formed. 12. The apparatus according to claim 11, characterized in that the shell (40) with a nozzle (39) on the bottom (41) is carried out, on which the tube (5) can be pushed and in which the check valve (22, 23) is arranged and that an insert (42) is arranged on the one hand as a holder for the valve body (23) and on the other hand as a seat for a tip (14) to be inserted at the bottom of the shell (40).

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