Precision balance for pipette calibration

Abstract

A precision balance (10) for pipette calibration, having a base (12), a weighing plate (14) and a load-receiving space (16) located thereabove, has a weighing system in the base (12). In the load-receiving space (16), a liquid-tight weighing vessel can be positioned on the weighing plate (14). The precision balance (10) also has a liquid-removal container (20) and a fastening device (18) for reversibly fastening the liquid-removal container (20) to the base (12).

Description

[0001] Precision scale for pipette calibration

[0002] The present invention relates to a precision scale with which pipettes can be calibrated.

[0003] For the gravimetric calibration of pipettes, high-resolution precision, analytical, semi-micro, micro or ultra-micro balances, hereinafter referred to as precision balances, are used.

[0004] When gravimetrically calibrating a net volume of pipettes using a precision balance, a volume of liquid to be determined is dispensed from the pipette tip into a weighing vessel, and the volume of the dispensed liquid is determined using a weight value determined by the precision balance.

[0005] Pipettes are calibrated with a calibration fluid, such as distilled or deionized water of grade 3 according to ISO 3696. Alternatively, calibration oil can be used. The calibration fluid is usually contained in a liquid extraction container located near the precision balance on a measuring station. To calibrate the pipette, the calibration fluid is removed from the liquid extraction container and pipetted into a weighing vessel located on the precision balance.

[0006] However, gravimetric calibration requires consideration of external climatic conditions such as air temperature, humidity, and air pressure around the precision balance, as these parameters affect the weight value and thus the pipette calibration. For example, air temperature and humidity influence the evaporation rate of the calibration liquid in the weighing vessel, thus distorting the weight value.

[0007] Especially with very small volumes, such as 1 liter, the influence of external climatic conditions on the weighing result and thus also on the accuracy of the pipette calibration cannot be ignored. Pipette calibration must therefore always be performed under constant climatic conditions. Calibrating a pipette according to ISO 8655-6 requires not only dedicated laboratories but also dedicated measuring stations that allow for very precise temperature and humidity control.

[0008] The object of the present invention is to improve the precision balance for pipette calibration described above in order to enable faster, more efficient, and less error-prone calibration of pipettes using a gravimetric measurement method. Furthermore, the present invention aims to reduce the space required for the calibration workflow.

[0009] The object is achieved according to the invention by a precision scale for pipette calibration, comprising a base, a weighing platform, and a load-bearing chamber located above it. A weighing system is housed in the base. A liquid-tight weighing vessel can be positioned in the load-bearing chamber on the weighing platform, into which calibration liquid can be pipetted using the pipette. The precision scale for pipette calibration also has a liquid withdrawal container and a fastening device for reversibly attaching the liquid withdrawal container to the base.

[0010] The basic idea of ​​the invention is to attach the liquid withdrawal container to the precision balance in order to, on the one hand, reduce the distance traveled by the pipette between the liquid withdrawal container and the weighing vessel during calibration and, on the other hand, to ensure improved stability of the liquid withdrawal container so that it cannot be accidentally knocked over during the calibration workflow. According to the invention, the liquid withdrawal container is attached to the precision balance so that the distance between the liquid withdrawal container and the weighing vessel is minimal. This saves time when calibrating the pipette and makes the calibration process more efficient. Furthermore, the time during which the calibration liquid in the pipette tip is exposed to potential interference factors such as ambient climatic conditions is reduced, thus enabling even more precise calibration of the pipette.

[0011] Furthermore, the present invention has the advantage that the precision balance requires less space or footprint than a comparable precision balance in which the liquid collection container is not attached to the balance. The footprint of the precision balance according to the invention is therefore particularly small. This is particularly advantageous because the space available for calibration is limited due to the high demands placed on the measuring station or laboratory.

[0012] Furthermore, the present invention offers the advantage that the liquid withdrawal container is thermally better connected to the scale and the weighing vessel than a withdrawal container that is significantly spaced apart from the scale and the weighing vessel. This reduces the temperature difference between the liquid withdrawal container and the weighing vessel.

[0013] According to one aspect of the invention, the fastening device enables tool-free attachment and detachment of the liquid collection container to the base. In particular, there is a positive connection between the liquid collection container and the base of the precision scale.

[0014] Tool-free attachment and detachment offers the advantage that the liquid container can be easily and quickly attached to and removed from the base at any time, for example, to clean, fill, or empty it. The positive connection between the liquid container and the base ensures that the liquid container can be attached to the base without any play. This ensures that the liquid container is particularly secure and held in place on the base.

[0015] For an even better hold of the liquid collection container, it can be mechanically locked to the base of the precision scale using a locking element, i.e. reversibly attached to the base of the precision scale.

[0016] The fastening device is preferably a plug-in connection, in particular, wherein the liquid dispensing container has at least one extension that can be inserted into a receptacle in the base. The extension of the liquid dispensing container allows it to be easily and quickly inserted into the receptacle in the base. Of course, the extension can also be provided on the base and the receptacle on the liquid dispensing container on the other side.

[0017] According to a further aspect of the invention, the receptacle for the liquid withdrawal container is arranged on the front of the precision balance. Compared to a side-mounted arrangement, this offers the advantage that, during pipette calibration, the path traveled by the pipette tip from the liquid withdrawal container to the weighing vessel is closer to the operator's body, which ensures more reliable positioning and requires less effort.

[0018] In particular, the receptacle is at least one upwardly open clamp into which at least one extension protruding from a base of the liquid withdrawal container can be inserted. The upwardly open clamp of the receptacle and the extension of the liquid withdrawal container are preferably designed such that the liquid withdrawal container can only be attached and detached from above. The liquid withdrawal container can therefore neither be inserted laterally nor removed forwards. This ensures a particularly secure fit of the liquid withdrawal container in the receptacle of the precision scale. In addition, the clamp or the extension can be designed such that the insertion simultaneously results in a lateral alignment of the liquid withdrawal container with respect to the base.

[0019] The extension protruding from the base of the liquid collection container can, in particular, be designed as an extension of a side surface of the liquid collection container. For example, the extension is formed integrally with the liquid collection container. In principle, the extension corresponds to a blade that can be inserted into the receptacle in the base.

[0020] According to the invention, the liquid collection container is arranged, viewed from above, between the weighing base and a display unit of the precision scale. With this arrangement, the precision scale requires the least space, as the liquid collection container does not protrude beyond the edge of the scale. Furthermore, the liquid is not handled above the display unit. The space requirements or footprint of a precision scale with and without a liquid collection container are therefore no different.

[0021] However, regardless of its location on the base, the liquid collection container is spaced apart from the weighing vessel located on the weighing base in order not to hinder the weighing process and falsify the weighing result.

[0022] According to the invention, the at least one extension can extend between the base and the display unit into the receptacle provided there. The liquid dispensing container can thus be secured above the extension between the base and the display unit.

[0023] The precision scale can also have a front panel, which serves to define the load-bearing area, particularly when the scale is used for weighing rather than for calibrating pipettes. The front panel is designed so that it can be inserted into the holder when the liquid collection container is removed. In other words, the holder of the precision scale serves either to hold the front panel or the liquid collection container. This offers the advantage that the existing holder for the front panel can be used for the liquid collection container, and no additional holder on the precision scale is required.

[0024] The liquid withdrawal container can be made of metal. It is also conceivable for the storage container to be made of a different material, although it is crucial that this material has a thermal conductivity comparable to that of metal, for example. Particularly good thermal conductivity has the advantage that the calibration liquid in the liquid withdrawal container can be heated or cooled to the ambient temperature as quickly as possible, thus enabling a particularly effective and rapid heat exchange between the environment and the calibration liquid. During calibration according to ISO 8655-6, the temperature of the calibration liquid must not deviate from the ambient temperature by more than 0.5 Kelvin. The better the thermal conductivity of the material of the liquid withdrawal container, the faster the pipette calibration can begin.Metal as a material for the liquid collection container also offers the advantage of enabling particularly uniform temperature compensation.

[0025] According to a further aspect of the invention, the liquid withdrawal container has a lid that at least partially covers the open top of the liquid withdrawal container. The lid can prevent, for example, dust or other contaminants from falling into the liquid withdrawal container from above and thus contaminating the calibration fluid. The lid also has the advantage that the liquid withdrawal container is more temperature-stable and the calibration fluid evaporates less. A lid that only partially covers the open top of the liquid withdrawal container ensures that calibration fluid can still be withdrawn from the liquid withdrawal container in the uncovered area, while the rest of the liquid withdrawal container is covered and thus protected from contamination.

[0026] The liquid sampling container can have several chambers inside. A multi-chamber system allows the same calibration liquid to be held in different chambers, whereby the temperature of the calibration liquids can be different in each chamber. A multi-chamber system therefore offers the advantage that one chamber contains a calibration liquid that has already been tempered and can be used to calibrate a pipette, while the calibration liquid in the other chamber(s) is still being tempered. In such a case, it is particularly advantageous if a wall separating the chambers is made of a material that is less thermally conductive than the actual liquid sampling container, so that the calibration liquid that is already at the correct temperature does not cool or heat up the calibration liquid that still needs to be tempered.Furthermore, different calibration fluids, such as water and calibration oil, can be contained in the multiple chambers.

[0027] According to the invention, it can be provided that the chambers are connected to one another via at least one passage, in particular wherein the at least one passage can be closed in a fluid-tight manner. If the passage is open, the same calibration liquid at the same temperature is present in both chambers. If the passage between the two chambers is closed, both chambers can contain different calibration liquids and / or calibration liquids at different temperatures. A closable passage thus makes it possible either to use the entire volume of all chambers simultaneously or to accommodate different calibration liquids, possibly with initially different temperatures. This offers the advantage that the liquid withdrawal container can be individually adapted to the prevailing circumstances and conditions.

[0028] The open passage also allows calibration fluid to be withdrawn from one chamber while the other chamber is completely covered, for example, with a lid. If calibration fluid is withdrawn from the uncovered chamber, calibration fluid flows back in from the covered chamber, so that the uncovered chamber serves as the withdrawal chamber, while the covered chamber serves as the storage chamber.

[0029] The fluid extraction container can have a side-mounted bypass with a sampling opening for the calibration fluid. Similar to the two-chamber system with an open passage, calibration fluid can be extracted through the sampling opening, while the actual fluid extraction container is closed with a lid and protected from contamination.

[0030] The bypass can run essentially parallel to a side wall of the liquid extraction container. The bypass's extraction opening is located approximately at the same height as the open top of the liquid extraction container. The bypass, which runs essentially parallel to the side wall, ensures that the calibration fluid flows from the liquid extraction container into the bypass as quickly and unhindered as possible, where it can be extracted. The fluid level in the bypass corresponds to the fluid level or the fluid height or column in the liquid extraction container.

[0031] According to a further aspect of the invention, a temperature sensor is assigned to the liquid withdrawal container, which serves to detect the temperature of the liquid withdrawal container and / or the calibration fluid contained therein. The temperature sensor can be arranged either inside the liquid withdrawal container, in or on one of the side walls or the bottom of the liquid withdrawal container, and / or outside the liquid withdrawal container. In particular, the temperature sensor continuously measures the temperature of the calibration fluid, thus recording a continuous temperature profile, which can be stored and / or analyzed if necessary.

[0032] In addition, additional (external) sensors can be assigned to the liquid sampling container, which can communicate with the precision scale, for example, so that the precision scale can perform a climatic check required by ISO Standard 8655-6. It is also possible for the liquid sampling container to have a sensor holder into which one or more sensors can be inserted to detect the environment, and whose measurement data can then also be evaluated.

[0033] The temperature sensor is connected to an internal or external controller via a signal transmission system, allowing the temperature measured by the temperature sensor to be transmitted to the controller and / or evaluated. It is also possible for the measured temperature to be recorded simultaneously by the controller, allowing documentation of the temperature of the calibration fluid. Recording and evaluation of the temperature sensor's measurement data is also possible via an external controller, such as a PC.

[0034] Further features and characteristics of the invention will become apparent from the figures and the following description, to which reference is made. The figures show:

[0035] Fig. 1 is a schematic side view of a precision scale according to the invention with a liquid withdrawal container;

[0036] Fig. 2 is a schematic side view of the precision balance of Fig. 1 with a liquid collection container removed from the holder; Fig. 3 is a schematic perspective top view of the fastening device of the precision balance of Fig. 1,

[0037] Fig. 4 is a schematic perspective view of the liquid withdrawal container from Fig. 1;

[0038] Fig. 5 is a schematic view of a liquid withdrawal container according to the invention with two chambers;

[0039] Fig. 6 is a schematic front view of a liquid withdrawal container according to the invention with two chambers and a bypass; and

[0040] Fig. 7 is a schematic perspective view of the liquid withdrawal container from Fig. 1 with a temperature sensor and a controller.

[0041] Figures 1 and 2 show a precision balance 10 with which pipettes, in particular pipettes with a maximum pipette volume of up to 10 ml, can be calibrated.

[0042] The precision scale 10 has a base 12 in which a weighing system (not shown) is accommodated.

[0043] Adjacent to the base 12 and firmly connected thereto, the precision balance 10 has a weighing base 14 on which either a weighing pan (not shown) or a liquid-tight weighing vessel (not shown) necessary for the calibration of pipettes can be positioned.

[0044] The weighing vessel serves to hold calibration fluid such as calibration oil and / or distilled or deionized water of quality 3 according to ISO 3696.

[0045] Above the weighing base 14 and around the weighing vessel is the load-bearing space 16, which is delimited at least on one side by the base 12 and which can be occupied by the weighing vessel.

[0046] Furthermore, the load-bearing space can of course be delimited laterally by a draft shield (not shown) in the form of glass and / or plastic panes, which can be coated, in particular antistatically coated. Furthermore, the load-bearing space can also be delimited by an evaporation trap, which is formed, for example, as part of the draft shield. The evaporation trap reduces the evaporation of the calibration liquid in the weighing vessel. Both the draft shield and the evaporation trap serve to reduce the environmental influences on the calibration process.

[0047] The precision scale 10 further comprises a fastening device 18 by means of which a liquid withdrawal container 20 can be reversibly and tool-freely attached to and detached from the base 12 of the precision scale 10.

[0048] The liquid withdrawal container 20 serves to provide calibration fluid for calibrating pipettes. To calibrate a pipette, calibration fluid is withdrawn from the liquid withdrawal container 20 and transferred to the weighing vessel.

[0049] The liquid withdrawal container 20 and the weighing vessel are always arranged at a distance from each other so that they do not touch each other.

[0050] The liquid sampling container 20 has a volume between 20 ml and 500 ml, allowing pipette calibration with a single filled liquid sampling container 20. The volume of calibration liquid that the liquid sampling container can hold depends primarily on the pipette to be calibrated. Depending on the pipette to be calibrated, different liquid sampling containers can be used, ensuring, for example, a prescribed immersion depth of the pipette tip for the entire duration of the pipette calibration.

[0051] The fastening device 18, with which the liquid withdrawal container 20 is fastened to the base 12, is designed such that the liquid withdrawal container 20 can be attached and detached from the base 12 quickly and easily at any time without the need for tools.

[0052] This is achieved in that the fastening device 18 is a plug-in connection formed on the one hand by an extension 22 protruding from the liquid withdrawal container 20 and a receptacle 24 arranged on the base 12. The extension 22 is formed integrally with the liquid withdrawal container 20 and is arranged on the liquid withdrawal container 20 such that it represents an extension of a side wall of the liquid withdrawal container 20. The extension 22 thus protrudes from a base of the liquid withdrawal container 20. However, this does not have to be the case; the extension 22 could just as easily run parallel to the side wall, so that the extension 22 and the adjacent side wall define a downwardly open slot between them. This would have the advantage that the liquid withdrawal container 20 can be put down at any time without tipping over.

[0053] To secure the liquid collection container 20, its extension 22 can be inserted into the receptacle 24 of the base 12 such that a positive connection is created between the liquid collection container 20 and the base 12. The exact structure of the fastening device will be discussed below in the description of Figures 3 and 4.

[0054] The receptacle 24 for the liquid withdrawal container 20 is arranged, as shown in Figures 1 to 3, on a front side 26 of the precision scale 10, so that the liquid withdrawal container 20 is also attached to the front side 26 of the precision scale 10 and thus delimits the load receiving space 16 towards the front.

[0055] If the precision scale 10 is not used to calibrate a pipette, but rather to weigh a sample, the liquid extraction container 20 can be removed and a front panel 27 inserted into the holder 24 instead. The front panel 27 then limits the load-bearing space 16 to the front instead of the liquid extraction container 20. The holder 24 is therefore multifunctional and serves either to accommodate the front panel 27 of the precision scale 10 or to accommodate the liquid extraction container 20.

[0056] In addition, the precision scale 10 has a display unit 28 that adjoins the extension 22 and encloses it between itself and the base 12. The liquid withdrawal container 20 is thus arranged, in plan view, between the weighing base 14 and the display unit 28 of the precision scale 10. In side view, it can be seen that the liquid withdrawal container 20 sits partially on and / or above the weighing base 14, but in front of the load-bearing space 16, where measurements are taken and on which the weighing vessel can be placed. This area is indicated in Figure 3 by the curved boundary of the load-bearing space 16.

[0057] The display 28 serves, among other things, to display the weight of a weighing object located in the load-bearing space 16, as measured by the precision scale 10. In addition, further data and measurement results can be displayed on the display unit 28.

[0058] The display 28 is preferably connected mechanically and, of course, in terms of signaling and energy to the rest of the precision scale 10.

[0059] The exact design of the fastening device 18, consisting of the extension 22 and the receptacle 24, is explained below and is shown in Figure 3.

[0060] The receptacle 24 is arranged on the front side 26 of the base 12 of the precision scale 10 and has three upwardly open U-shaped clamps 30, which together form the receptacle 24 for the liquid withdrawal container 20. Alternatively, one or more of the clamps 30 can be V-shaped.

[0061] Each clamp 30 has two legs and a central portion connecting the legs, with one of the two legs being formed by the base 12 itself. The other leg, a clamp leg 31, is spaced from the base 12.

[0062] The clamp legs 31 of the three clamps have different lengths, with the clamp leg 31 of the middle clamp 30 being the longest.

[0063] Of course, it is possible for the clamp legs 31 to be connected to the base 12 via a web to stabilize them. The clamps 30 would then have a T- or H-shaped cross-section when viewed from above.

[0064] Furthermore, the fastening device 18 has a centrally arranged, additional U-shaped stop element 32, which serves as an (additional) height stop for the extension 22 of the liquid withdrawal container 20. The counterpart to the clamps 30 of the receptacle 24 of the base 10 is formed by three guides 34, which extend vertically from one end of the extension 22 toward the liquid withdrawal container 20 and are formed in the extension 22. The guides 34 are shown in Figure 4.

[0065] In an assembled state, all three guides 34 engage in a form-fitting manner with the clamps 30 of the receptacle 24 of the base 12 and thus fix the liquid withdrawal container 20 to the base 12. Because the guides 34 also contact the clamps 30 laterally, the liquid withdrawal container 20 is aligned with the base 12 in all three spatial directions.

[0066] At least the centrally arranged guide 34 has two webs 36, which are designed to rest against the rear of the clamp leg 31 and prevent the liquid withdrawal container 20 from being removed forward from the precision scale 10. As mentioned, a lateral displacement of the liquid withdrawal container 20 relative to the base 12 is not possible.

[0067] Due to the webs 36, it is only possible to insert the liquid collection container from above onto the base 12 of the precision scale 10 or to remove it upwards.

[0068] In order to prevent accidental vertical movement of the liquid withdrawal container 20 relative to the base 12, both the liquid withdrawal container 20 and the base 12 can additionally have mechanical locking elements (not shown).

[0069] The liquid collection container 20 has a sufficient width in plan view to simultaneously fill a multi-channel pipette with up to twelve channels. The length of the liquid collection container 20 in the direction of the precision balance 10 can therefore be significantly smaller than its width perpendicular to it.

[0070] As can also be clearly seen from Figure 4, the liquid withdrawal container has a non-cuboid shape.

[0071] The liquid withdrawal container 20 is designed such that it has a long rear side 38, to which the extension 22 is connected, and a front side 40 opposite the rear side 38 and smaller than the rear side 38.

[0072] The front side 40 is connected to a bottom 44 of the liquid withdrawal container 20 via an inclined side 42. Together with two pentagonal side walls 45, which have two substantially right angles, the liquid withdrawal container 20 forms a single internal chamber 46.

[0073] The inclined side 42 simplifies the removal of calibration fluid from the fluid collection container 20 when the fluid level is low. The calibration fluid thus collects more precisely in the lower area of ​​the chamber 46.

[0074] The front 40, the back 38, the sloped side 42, the base 44, and the two side walls 45 are made of metal, for example, because metal is a particularly good thermal conductor, allowing the temperature of the calibration fluid held in the fluid withdrawal container 20 to adjust to the ambient temperature as quickly and efficiently as possible. Metal as the material for the fluid withdrawal container 20 also offers the advantage of enabling particularly uniform temperature compensation of the calibration fluid in one chamber 46.

[0075] The interior of the liquid withdrawal container 20 may also have more than one chamber 46. As shown in Figures 5 and 6, the liquid withdrawal container has an additional chamber 48 inside.

[0076] The two chambers 46, 48 are separated from each other by a wall 50 which is particularly poorly heat-conducting.

[0077] A multi-chamber system allows two different calibration fluids to be held in a fluid withdrawal container 20. For example, the first chamber 46 can hold water, while the second chamber 48 can hold a calibration oil.

[0078] It is also conceivable that in the first chamber 46 and in the second

[0079] Chamber 48 contains the same calibration liquid, but the two calibration liquids in the two chambers 46, 48 have different temperatures because, for example, one chamber has just been filled with new calibration liquid.

[0080] While in the first chamber 46 the calibration fluid is already at the correct temperature for calibration, the calibration fluid in the second chamber 48 may have a different temperature that does not correspond to the correct temperature for calibration.

[0081] The first chamber 46 thus serves as a kind of working chamber from which calibration fluid can be drawn for calibration, while in the second chamber 48, a calibration fluid is first brought to the correct temperature. Thus, in this case, the second chamber 48 serves as an acclimatization chamber.

[0082] The two chambers 46, 48 can be fluidically connected to each other via a passage 49 in the wall 50 so that the calibration fluid can flow from the first chamber 46 into the second chamber 48.

[0083] Because the passage 49 in the wall 50 can be fluidically closed, for example by means of a plug movable from the outside, the liquid withdrawal container 20 can be operated either as a liquid withdrawal container 20 with two separate fluidically separated chambers 46, 48 or, for example if larger calibration fluid volumes are required for calibration, as one large chamber comprising two interconnected smaller chambers 46, 48.

[0084] To protect the calibration liquid in the liquid withdrawal container 20 from contamination, for example from dust, and to protect the calibration liquid from evaporation, the liquid withdrawal container can have a lid 52 that covers at least part of an open top 54 of the liquid withdrawal container 20.

[0085] The liquid withdrawal container 20 shown in Figure 6 has such a lid 52 which covers the entire open top 54 of the liquid withdrawal container with two chambers 46, 48.

[0086] To still allow the calibration fluid to be removed, the fluid removal container 20 has a bypass 56. The bypass has a removal opening 58 that is only large enough to allow a pipette tip 60 of a pipette to be inserted into the opening without too much of the calibration fluid evaporating through the removal opening 58.

[0087] The bypass 56 extends substantially parallel to the side walls 45 of the liquid withdrawal container 20.

[0088] An outlet of the bypass 56 is arranged as close as possible to the bottom 44 of the liquid withdrawal container 20, so that even when the calibration liquid level 62 is very low, calibration liquid can still be withdrawn via the bypass.

[0089] As shown in Figure 7, the liquid withdrawal container 20 may have a temperature sensor 64 which detects the temperature of the liquid withdrawal container 20 and / or the calibration liquid temperature present therein.

[0090] The temperature sensor 64 can be designed such that it permanently measures the temperature of the liquid withdrawal container and / or the calibration liquid contained therein.

[0091] The temperature sensor 64 is associated with one of the side walls 45, the rear side 38, the front side 40, the sloping side 42 and / or the bottom 44.

[0092] It is also possible for the temperature sensor 64 to be incorporated into one of the sides of the liquid withdrawal container 20.

[0093] In the event that the temperature sensor 64 only detects the temperature of the liquid withdrawal container, the temperature sensor 64 can also be arranged outside the chamber 46, i.e. on an outer side of the liquid withdrawal container 20.

[0094] The temperature sensor 64 can be connected to a controller 66 so that the temperatures measured by the temperature sensor 64 can be transmitted directly to the controller 66. The controller 66 can store and / or evaluate the temperatures measured by the temperature sensor 64. The controller 66 is accommodated in the base 12 of the precision scale 10. In addition, the liquid withdrawal container 20 can have further sensor receptacles into which additional sensors can be accommodated, with which, for example, the climatic conditions of the environment can be measured and detected. The data recorded by the temperature sensor 64 or the additional sensors present can be evaluated and saved via the internal controller 66 and / or appropriate software on an external device.

Claims

Patent claims 1. Precision balance (10) for pipette calibration, with a base (12), a weighing floor (14) and a load-bearing space (16) located above it, wherein a weighing system is accommodated in the base (12) and a liquid-tight weighing vessel can be positioned in the load-bearing space (16) on the weighing floor (14), and with a liquid withdrawal container (20) and a fastening device (18) for the reversible fastening of the liquid withdrawal container (20) to the base (12).

2. Precision scale (10) according to claim 1, characterized in that the fastening device (18) enables tool-free fastening and detachment of the liquid withdrawal container (20) to the base (12), in particular with a positive connection.

3. Precision scale (10) according to claim 2, characterized in that the fastening device (18) is a plug-in connection, in particular wherein the liquid withdrawal container (20) has at least one extension (22) which can be inserted into a receptacle (24) in the base (12).

4. Precision scale (10) according to claim 3, characterized in that the receptacle for the liquid withdrawal container (20) is arranged on a front side (26) of the precision scale (10), in particular wherein the receptacle (24) is at least one upwardly open clamp (30) into which at least one extension (22) projecting from the bottom (44) of the liquid withdrawal container (20) can be inserted.

5. Precision scale (10) according to one of the preceding claims, characterized in that the liquid removal container (20) is arranged at least partially between the weighing base (14) and a display unit (28) of the precision scale (10) in plan view.

6. Precision scale (10) according to claim 5 and additionally according to claim 3 or 4, characterized in that the at least one extension (22) between the base (12) and the display unit (28) projects into the receptacle (24) provided there.

7. Precision balance (10) according to one of the preceding claims, as far as dependent on claim 3, characterized in that the precision balance (10) a front panel (27) for delimiting the load-receiving space (16), wherein the front panel (27) is designed such that it can be inserted into the receptacle (24) when the liquid withdrawal container (20) is removed.

8. Precision scale (10) according to one of the preceding claims, characterized in that the liquid withdrawal container (20) is made of metal.

9. Precision scale (10) according to one of the preceding claims, characterized in that the liquid withdrawal container (20) has a lid (52) which at least partially covers the open top (54) of the liquid withdrawal container (20).

10. Precision scale (10) according to one of the preceding claims, characterized in that the liquid withdrawal container (20) has a plurality of chambers (46, 48) in the interior.

11. Precision balance (10) according to claim 10, characterized in that the chambers (46, 48) are connected to one another via at least one passage (49), in particular wherein the at least one passage (49) can be closed in a fluid-tight manner.

12. Precision balance (10) according to one of the preceding claims, characterized in that the liquid withdrawal container (20) has a laterally arranged bypass (56) with a withdrawal opening (58) for withdrawing the calibration liquid.

13. Precision scale (10) according to claim 12, characterized in that the bypass (56) runs substantially parallel to a side wall (45) of the liquid withdrawal container (20).

14. Precision scale (10) according to one of the preceding claims, characterized in that a temperature sensor (64) is assigned to the liquid withdrawal container (20) for detecting the temperature of the liquid withdrawal container (20) and / or calibration liquid present therein.

15. Precision scale (10) according to claim 14, characterized in that the temperature sensor (64) is connected to a controller (66) in the base (12) for exchanging information.

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