TREATMENT DEVICE FOR CONTAINERS AND / OR PREFORMS AND METHOD FOR CONTROLLING THE TREATMENT DEVICE

Description

[0001] The invention relates to a treatment device for containers and / or preforms and a method for controlling the treatment device.

[0002] Treatment devices for containers and / or preforms are known from US 2022 / 390399 A1, DE 602 02 362 T2, DE 10 2016 125027 A1, DE 602 04 543 T2, EP 1 858 560 B1 and EP 2 354 017 A1. US 2022 / 390399 A1, for example, discloses a device according to the preamble of claim 1.

[0003] In the production and filling of containers made from preforms, equipment can be used that includes handling devices for the containers or preforms, such as stretch blow molding machines, form-filling machines, and / or filling machines. These handling devices can be sterilized for aseptic use. This is achieved by introducing sterilizing agents into the handling devices, which sterilize the surfaces of the devices. Hydrogen peroxide, for example, can be used for sterilization. The concentration of hydrogen peroxide in the ambient air during sterilization of the handling device can range from 1000 ppm to 5000 ppm.These concentrations of sterilizing agents are generally very harmful to health, so operating / maintenance personnel may only enter the treatment device after the sterilizing agents have been removed from the treatment device.

[0004] The legal limits for substances such as hydrogen peroxide, which must be below the threshold before personnel enter the treatment device, are usually in the range of 0.5 ppm to 2 ppm. Access to the treatment device may only be granted once a sensor registers this reading or a lower value. It is known to use sensors with a measuring range encompassing these values ​​on the treatment device.

[0005] Therefore, it is necessary to monitor the concentration of sterilizing agent in the treatment device to prevent health risks to operating / maintenance personnel. Measuring sterilizing agent in the sterilization process for containers is known, for example, from EP 1 858 560 B1, and the sensors used for this purpose can also be used to monitor the concentration of sterilizing agent within treatment devices. However, after the concentration of the sterilizing agent in the treatment device drops, these sensors require a comparatively long time to display correct concentration values, as the sterilizing agent must first escape from the sensor.

[0006] The object of the invention is to provide a treatment device for containers and / or preforms and a method for controlling the treatment device, in which, after sterilization of a treatment device, correct values ​​for the concentration of the sterilizing agent in the treatment device are displayed more quickly than in the prior art.

[0007] The problem is solved by the features of the independent claims. Advantageous further developments are the subject of the dependent claims and the following description.

[0008] In a treatment device for containers and / or preforms, comprising a housing with an interior space and a first measuring device for measuring a concentration of a fluid in a first concentration range in the interior space, the invention provides that the treatment device has a second measuring device connected to the interior space via a fluid communication connection for measuring a concentration of the fluid in a second concentration range in the interior space and a separating device for the first measuring device, wherein the separating device provides a fluid communication connection between the first measuring device and the interior space in a first operating state and separates the fluid communication connection in a second operating state, wherein the second concentration range has at least one sub-range which has higher concentrations than the first concentration range.

[0009] The invention provides a treatment device which, in addition to the first measuring device, has a second measuring device capable of measuring higher concentrations than the first measuring device, at least in at least one sub-range of the second concentration range. The first measuring device can therefore be suitable for measuring comparatively low concentrations, and the second measuring device for measuring comparatively high concentrations. As soon as the concentration increases from a low concentration, the separating device can disconnect the fluid connection between the first measuring device and the interior of the treatment device. This means that the separating device can then switch to its second operating state. The first measuring direction can thus be shielded by the separating device from high concentrations of the fluid that lie outside the first concentration range.When the separation device is in its second operating state, the first measuring device is not exposed to high concentrations of fluid from the interior. The fluid concentration measurement can then continue with the second measuring device. As soon as the concentration decreases, the separation device can switch to its first operating state to re-establish the fluid connection between the interior and the first measuring device. The first measuring device is then exposed only to low concentrations of fluid and can therefore provide accurate concentration values ​​significantly faster than in the prior art. Operating / maintenance personnel can thus enter the treatment device earlier than in the prior art.

[0010] The first concentration area and the second concentration area can, for example, overlap in an overlap area.

[0011] This allows the two measuring devices to detect a continuous concentration range. The concentration can be tracked seamlessly when switching between concentration ranges.

[0012] For example, the separating device can be configured to switch to the second operating state when the first measuring device outputs a measured value that is greater than a predefined first threshold, and to switch to the first operating state when the second measuring device outputs a measured value that is below a second predefined threshold.

[0013] The first threshold can be a concentration value located within the first concentration range. Exceeding the first threshold, i.e., moving from lower to higher concentrations, triggers the switching of the separation device to the second operating state. This means that the fluid connection between the interior and the first measuring device is severed, preventing the first measuring device from being exposed to high concentrations of the fluid. Furthermore, falling below the second threshold, which can be a concentration value located within the second concentration range, from high to lower concentrations, is then detected by the second measuring device. Once this occurs, the separation device can switch back to the first operating state, re-establishing fluid contact between the first measuring device and the interior.

[0014] In particular, if an overlap zone exists, it can be further provided that the first and second threshold values ​​are the same and have a concentration value located within the overlap zone. That is, both the first and second measuring devices can detect whether a concentration value exceeds the threshold value above or below it.

[0015] According to one example, the separating device may include a fluid blocking device, in particular a valve, a flap, a door or a slide between the first measuring device and the interior.

[0016] This allows the first measuring device to be fluidically isolated from the interior by closing the valve or slide. Opening the valve or slide can establish a fluid connection between the interior and the first measuring device.

[0017] According to another example, the second measuring device can be located inside the building.

[0018] The second measuring device can thus directly measure the concentration in the ambient air inside the treatment device. In this case, a separation of the fluid connection between the second measuring device and the interior is not necessary. The measuring device can then, for example, continuously record measured values ​​for the fluid concentration in the interior, regardless of whether the first measuring device is separated from the interior by the separating device. This simplifies the handling of the second measuring device.

[0019] Furthermore, the treatment device may, for example, include a control device for controlling the separation device and for receiving measured values ​​from the first measuring device and the second measuring device.

[0020] The control device can then be used to control the change of the separating device between the first functional state and the second functional state based on the measured values ​​of the first measuring device or the second device.

[0021] According to another example, a fluid line can connect the interior to the first measuring device, and the separating device can open the fluid line in the first operating state and close it in the second operating state.

[0022] The first measuring device is thus located outside the interior of the housing of the container pin. Air from the interior of the housing can then flow to the first measuring device via the open fluid line, allowing the first measuring device to determine the concentration of the fluid in the air. To terminate the fluid connection between the interior and the first measuring device, the fluid line can be closed by the separating device. Since the fluid line can have a small cross-section, especially compared to the interior, the size of the separating device can be kept small.

[0023] The treatment device may, for example, further include a rinsing device for rinsing the first measuring device with a rinsing medium.

[0024] The flushing device can flush the first measuring device with the flushing medium when the separating device is in its second operating state. Fluid that has accumulated on the first measuring device after the fluid connection between the interior and the first measuring device has been severed can be at least largely removed by flushing. If the first measuring device is connected to the interior via a fluid line, the fluid can also be flushed out of the fluid line.

[0025] For example, the flushing device can have a valve and a flushing line which can be connected to the first measuring device via the valve in a fluid-communication manner.

[0026] The flushing line can, for example, be connected to the optional fluid line described above. The connection of the flushing line can be made between the separating device and the first measuring device. The flushing line can, for example, be fluid-communicating with an environment surrounding the treatment device, in which no fluid or only traces of fluid are present. The maximum permissible concentration of fluid in the ambient air is lower than the limit values ​​mentioned above.

[0027] The treatment device can, for example, include a suction device that is fluidly connected to the first measuring device, wherein the first measuring device is preferably arranged between the separating device and the suction device.

[0028] The extraction device can, for example, draw fluid-laden air from the interior to the first measuring device when the separating device is in its first operating state. When the separating device is in its second operating state and a flushing line is provided, the extraction device can, for example, draw flushing medium, particularly room air that contains no fluid, to the first measuring device. For this purpose, the first measuring device can be positioned between the extraction device and the separating device or the flushing line.

[0029] For example, the fluid could be a sterilizing agent, in particular hydrogen peroxide.

[0030] However, this does not preclude the possibility that the fluid may alternatively or additionally contain another sterilizing agent, such as peracetic acid, or may be suitable for another purpose.

[0031] According to another example, the second concentration range can have concentration values ​​between 10 ppm and 100,000 ppm, preferably 50 ppm and 50,000 ppm, more preferably 70 ppm and 10,000 ppm, and most preferably 100 ppm and 7,000 ppm.

[0032] Using hydrogen peroxide as an example, the concentration of hydrogen peroxide during the sterilization of a treatment device can range from 500 ppm to 5000 ppm. Therefore, the second measuring device, with the aforementioned concentration range, can detect values ​​for concentrations that may occur during sterilization and cannot be displayed by the first measuring device.

[0033] Furthermore, the treatment device can include at least one forming machine for shaping preforms into containers and / or a filling machine for filling containers. The forming process can be carried out, for example, by stretch blow molding or by filling with the container's intended contents.

[0034] The invention further relates to a method for controlling a treatment device according to the preceding description, wherein the separation device switches to the second operating state when the first measuring device outputs a measured value for the concentration that is greater than a first predefined threshold value, and switches to the first operating state when the second measuring device outputs a measured value for the concentration that is below a second predefined threshold value.

[0035] According to an example, a control device of the treatment device for controlling the treatment device, in particular for door interlocks, extraction, ventilation, a production stop and / or a production release, can take into account measured values ​​of the first measuring device when the separating device is in the first operating state, and take into account measured values ​​of the second measuring device when the separating device is in the second operating state.

[0036] The advantages, effects, and further developments of the procedure derive from the advantages, effects, and further developments of the treatment device described above. To avoid repetition, reference is therefore made to the preceding description in this regard.

[0037] The invention is described below with reference to exemplary embodiments and the accompanying drawing. The drawing shows: Figure 1 is a schematic representation of the treatment device according to a first embodiment; Figure 2 is a schematic representation of the treatment device according to a second embodiment; Figure 3 is a schematic representation of the treatment device according to a third embodiment; Figure 4 is a schematic representation of concentration areas and overlap areas; and Figure 5 is a flowchart of the process.

[0038] The treatment device is hereinafter referred to in its entirety by reference numeral 10, as for example in Figure 1 depicted.

[0039] The treatment device 10 is designed for treating containers and / or preforms. Treatment of containers and / or preforms includes, for example, forming preforms into containers or filling containers. However, this does not exclude other treatment possibilities.

[0040] The treatment device 10 has a housing 12 that encloses an interior space 14. The housing 12 may have a door element 48 for operating personnel, through which operating personnel can enter the interior space 14 of the treatment device 10.

[0041] Furthermore, a first measuring device 16 is fluidically connected to the interior 14. For this purpose, the first measuring device 16 can be connected to the interior 14 via a fluid line 40. The fluid line 40 can be controlled by a separating device 24. In a first operating state of the separating device 24, the fluid line 40 is open, so that a fluid connection exists between the interior 14 and the first measuring device 16. In a second operating state of the separating device 24, the fluid line 40 is closed, so that there is no longer a fluid connection between the interior 14 and the first measuring device 16.

[0042] In this example, the separating device 24 is designed as a valve with which the fluid line 40 can be opened and closed.

[0043] The first measuring device 16 has a first measuring range 18 for concentrations of a fluid, in particular hydrogen peroxide in air, as shown in Figure 4 The first measuring range 18 covers concentration values ​​below a legal limit for the fluid in the air, at which operating personnel can enter the interior space 14. This limit could, for example, be 0.5 ppm. This means that the first measuring range 18 extends at least to a concentration value of 0.5 ppm.

[0044] The treatment device 10 further comprises a second measuring device 20, which is fluidically connected to the interior 14. The second measuring device 20 has a second measuring range 22. As shown in Figure 4, the second measuring range 22 overlaps with the first measuring range 18. Furthermore, the second measuring range 22 has a sub-range 26, which exhibits higher concentration values ​​than the first measuring range 18. Therefore, the second measuring range 22 is shifted towards higher concentrations compared to the first measuring range 22.

[0045] The separating device 24 can be configured to switch to the second operating state when the first measuring device 16 detects measured values ​​that are within the overlap range 28 and continue to increase. For this purpose, a threshold value 27 can, for example, be defined within the overlap range 28. As soon as the first measuring device 16 measures a concentration greater than the threshold value 27, the separating device 24 can switch to the second operating state.

[0046] Furthermore, it is conceivable that in another example, two threshold values ​​could be defined. For instance, a low first threshold could be used when values ​​are rising, in order to lock the first measuring device 16 in time so that it is not overloaded by rapidly increasing values. When values ​​are falling, a high second threshold could then be used, so that the first measuring device 16 can be switched on again earlier when the second measuring device 20 determines that the concentration has fallen below the second threshold.

[0047] By disconnecting the fluid connection between the interior 14 and the first measuring device 16, the first measuring device 16 is decoupled from the interior 14. The first measuring device 16 can therefore be considered switched off.

[0048] Conversely, the separating device 24 can be further configured to transition to the first operating state when the second measuring device 20 detects measured values ​​that are within the overlap range 28 and continue to decrease. For example, the threshold value 27 can also be used here. As soon as the second measuring device 20 detects measured values ​​that are lower than the threshold value 27, the separating device 24 can transition to the first operating state.

[0049] The second measuring device 20 can be configured to continuously provide measured values. Separation of the fluid connection between the second measuring device 20 and the interior 14 when the threshold value 27 is undershot is not necessary.

[0050] The treatment device 10 can further include a control device 30, which can be configured to evaluate the measured values ​​provided by the first measuring device 16 or the second measuring device 20 and compare them with the threshold value 27. For this purpose, the control device 30 can be connected to the first measuring device 16 via a first signal connection 38. The control device 30 can be connected to the second measuring device 20 via a second signal connection 32.

[0051] The control device 30 can be connected to the disconnecting device 24 via a third signal connection 34. The signal connections can be wireless or wired.

[0052] As long as the measured values ​​for the fluid concentration are below threshold 27, the control device 30 can only consider measured values ​​from the first measuring device 16. If the measured values ​​from the first measuring device 16 indicate that the fluid concentration exceeds threshold 27, the control device 30 can output a signal via the third signal connection 34 to the separating device 24, which switches the separating device 24 to the second operating state. This closes the fluid connection between the first measuring device 16 and the interior 14.

[0053] From this point on, the control device can use 30 measured values ​​from the second measuring device 20 to monitor the concentration of the fluid in the interior 14. Measured values ​​from the first measuring device 16 can then be disregarded.

[0054] As soon as the readings from the second measuring device 20 indicate that the fluid concentration falls below the threshold value 27 again, the control device 30 can send another signal to the separating device 24, which switches the separating device 24 to its first operating state. The fluid connection between the first measuring device 16 and the interior 14 is then reopened.

[0055] Once the fluid connection is reopened, the control device can use 30 readings from the first measuring device 16 to monitor the fluid concentration. Readings from the second measuring device 20 can then be disregarded.

[0056] Furthermore, for example, the door element 48 can be locked via a control signal, which can be transmitted to the door element 48 via a fourth signal connection 50, as soon as the legal limit for the concentration of the fluid in the interior 14 is exceeded.

[0057] Furthermore, if the concentration falls below the legally defined limit, the control device 30 can transmit a control signal to the door element 48, which then unlocks the door element 48. This restores access to the interior 14 for operating personnel.

[0058] In Figure 2 Another embodiment of the treatment device 10 is shown. In comparison to the example according to Figure 1 The second measuring device 20 is arranged directly in the interior 14. For this purpose, the second measuring device 20 can, for example, be attached to the housing 12.

[0059] In this embodiment according to Figure 2 The treatment device 10 can have a suction device 46. The suction device 46 can be fluid-connected to the first measuring device 16. During operation, the suction device 46 causes air to be drawn away from the first measuring device 16. When the separating device 24 is in its first operating state, the suction device 46 therefore draws air from the interior 14 to the first measuring device 16. After the separating device 24 switches to its first operating state, the correct concentration of the fluid in the air in the interior 14 can thus be determined even more quickly by the first measuring device 16. Once the air has passed through the first measuring device 16 and the suction device 46, it can be released into the environment via an exhaust pipe.

[0060] The extraction device 46 can be arranged such that the first measuring device 16 is arranged between the extraction device 46 and the interior 14.

[0061] Furthermore, in this embodiment, the treatment device 10 can include a flushing device 41. The flushing device 41 can have a flushing line 42 which is fluidly connected to the first measuring device 16. Since the first measuring device 16 is connected to the interior 14 via a fluid line 40 in this example, the flushing line 42 can branch off from the fluid line 40. The flushing line 42 is fluidly connected to the first measuring device 16 between the separating device 24 and the first measuring device 16.

[0062] Furthermore, the flushing device 41 has a valve 44 that controls the flushing line 42. Opening the valve 44 releases the flushing line 42. When the valve 44 is closed, the flushing line 42 is blocked.

[0063] The control device 30 can be connected to the valve 44 via a fifth signal connection 36. The control device 30 can transmit control signals to the valve 44 via this fifth signal connection 36 to open or close the valve 44.

[0064] When the separating device 24 enters the first operating state, the control device 30 can instruct the valve 44 to close. When the separating device 24 enters the second operating state, the control device 30 can instruct the valve 44 to open. Thus, the flushing line 42 is only open when there is no fluid connection between the first measuring device 16 and the interior 14.

[0065] When the separating device 24 is in its second operating state, the suction device 46 can pump rinsing medium, for example ambient air, to the first measuring device 16 via the rinsing line 42 with the valve 44 open. The rinsing medium can then flush air, which may be, for example, a sterilizing agent, from the first measuring device 16.

[0066] According to Figure 3 A third embodiment of the treatment device 10 is shown. In this example, the first measuring device 16 is arranged in a section 52 of the housing 12 that can be separated from the interior 14. The separable section 52 can be separated from the rest of the interior 14 by the separating device 24. The separating device 24 can, for example, be designed as a slide.

[0067] In this example, the flushing line 42 can branch off from the separable section 52. Furthermore, the suction device 46 can be connected to the separable section 52.

[0068] Figure 4 The concentration ranges 18, 22 of the first measuring device 16 and the second measuring direction 20 are represented on a logarithmic scale. The scale shows the concentration of the fluid in the air, ascending from left to right.

[0069] The first concentration range 18 of the first measuring device 16 can, for example, extend from less than 0.1 ppm to approximately 300 ppm. However, other limit values ​​for the first concentration range 18 are not excluded.

[0070] The second concentration range 22 can, for example, extend from a concentration value of 100 ppm to approximately 7000 ppm. Other limit values ​​for the second concentration range 22 are also conceivable.

[0071] The second concentration range 22 includes at least one sub-range 26 which has higher concentration values ​​than the first concentration range 18.

[0072] In the overlap region 28, the first concentration region 18 and the second concentration region 22 overlap. In this example, the overlap region 28 can extend from 100 ppm to 300 ppm. Within the overlap region 28, both the first measuring device 16 and the second measuring device 20 can provide correct readings.

[0073] In the overlap area 28, a threshold value 27 can be defined, the exceeding of which triggers a change in the functional state of the separating device 24.

[0074] This can be illustrated, for example, with the flowchart from Figure 5 shown, which represents an embodiment of method 100.

[0075] Starting from a situation in which the separating device 24 is in its first operating state and the measuring device 16 displays measured values ​​indicating a fluid concentration in the range below 0.5 ppm, in a first step 102, for example, the control device 30 can be used to acquire the measured values ​​of the first measuring device 16.

[0076] In a further step 104, for example by the control device 30, it can be compared whether the measured values ​​exceed the threshold value 27. If this is not the case, the measured values ​​of the first measuring device 16 are recorded again according to step 102.

[0077] If the measured values ​​exceed the threshold value 27, the process continues with step 106. In this step, the separating device 24 is switched to the second operating state. From this point on, the measured values ​​of the second measuring device 20 are used, and no longer those of the first measuring device 26.

[0078] In step 108, the measured values ​​of the second measuring device 20, for example by the control device 30, are therefore recorded.

[0079] In a further step 110, a comparison can be made to determine whether the measured values ​​of the second measuring device 20 fall below the threshold value 27. This can be carried out, for example, by the control device 30.

[0080] If this is not the case, proceed to step 108 and continue using the measured values ​​from the second measuring device 20.

[0081] If the measured values ​​of the second measuring device 20 fall below the threshold value 27, the separating device 24 is returned to its first operating state according to step 112. From this point on, the measured values ​​of the first measuring device 16 are used and those of the second measuring device 20 are no longer taken into account.

[0082] The process can then continue with step 102, in which the measured values ​​of the first measuring device 16 are recorded.

[0083] Optionally, the procedure can include 100 further steps, for example, unlocking or activating the door element 48 if the concentration is below 0.5 ppm.

[0084] All of the above steps can be performed by the control device 30. Reference symbol list

[0085] 10 Treatment device 12 Housing 14 Interior 16 First measuring device 18 First concentration range 20 Second measuring device 22 Second concentration range 24 Separating device 26 Subrange 27 Threshold 28 Overlap range 30 Control device 32 Second signal connection 34 Third signal connection 36 Fifth signal connection 38 First signal connection 40 Fluid line 41 Flushing device 42 Flushing line 44 Valve 46 Extraction device 48 Door element 50 Fourth signal connection 52 Separable range

Claims

1. Treatment device (10) for containers and / or preforms, comprising a housing (12) with an interior space (14) and a first measuring device (16) for measuring a concentration of a fluid in a first concentration range (18) in the interior space (14), wherein the treatment device (10) has a second measuring device (20) connected to the interior space (14) in a fluid-communicating manner for measuring a concentration of the fluid in a second concentration range (22) in the interior space (14), characterised in that the treatment device (10) has a separating device (24) for the first measuring device (16), wherein the separating device (24) in a first functional state provides a fluid-communicating connection between the first measuring device (16) and the interior space (14) and in a second functional state separates the fluid-communicating connection, the second concentration range (22) having at least one subrange (26) which has higher concentrations than the first concentration range (18).

2. Treatment device (10) according to claim 1, characterised in that the first and second concentration ranges (22) overlap in an overlap range (28).

3. Treatment device (10) according to claim 1 or 2, characterised in that the separating device (24) is configured to switch to the second functional state when the first measuring device (16) outputs a measurement that is above a first predefined threshold value (27), and to switch to the first functional state when the second measuring device (20) outputs a measurement which is below a second predefined threshold value (27).

4. Treatment device (10) according to any of the preceding claims, characterised in that the separating device (24) has a fluid blocking device, in particular a valve, a flap, a door or a slide, between the first measuring device (16) and the interior space (14).

5. Treatment device (10) according to any of the preceding claims, characterised in that the second measuring device (20) is arranged in the interior space (14).

6. Treatment device (10) according to any of the preceding claims, characterised in that the treatment device (10) further comprises a control device (30) for controlling the separating device (24) and for receiving measurements from the first measuring device (16) and the second measuring device (20).

7. Treatment device (10) according to any of the preceding claims, characterised in that a fluid line (40) connects the interior space (14) to the first measuring device (16), and the separating device (24) opens the fluid line (40) in the first functional state and closes it in the second functional state.

8. Treatment device (10) according to any of the preceding claims, characterised in that the treatment device (10) further comprises a rinsing device (41) for rinsing the first measuring device (16) with a rinsing medium.

9. Treatment device (10) according to the preceding claim, characterised in that the rinsing device (41) has a valve (44) and a rinsing line (42) which can be connected to the first measuring device (16) in a fluid-communicating manner by means of the valve.

10. Treatment device (10) according to any of the preceding claims, characterised in that the treatment device (10) has a suction device (46) which is connected to the first measuring device (16) in a fluid-communicating manner, the first measuring device (16) preferably being arranged between the separating device (24) and the suction device (46).

11. Treatment device (10) according to any of the preceding claims, characterised in that the fluid is a sterilising agent, in particular hydrogen peroxide.

12. Treatment device (10) according to any of the preceding claims, characterised in that the second concentration range (22) has concentration values from 10 ppm to 100,000 ppm, preferably 50 ppm to 50,000 ppm, more preferably 70 ppm to 10,000 ppm, most preferably from 100 ppm to 7,000 ppm.

13. Treatment device (10) according to any of the preceding claims, characterised in that the treatment device (10) has at least one forming machine for converting preforms into containers and / or a filling machine for filling containers.

14. Method (100) for controlling a treatment device (10) according to any of the preceding claims, wherein the separating device (24) switches to the second functional state (106) when the first measuring device (16) outputs a concentration measurement that is above a first predefined threshold value (27), and switches to the first functional state (112) when the second measuring device (20) outputs a concentration measurement which is below a second predefined threshold value (27).

15. Method (100) according to claim 14, characterised in that a control device (30) of the treatment device (10) for controlling the treatment device (10), in particular for door locking, suction, ventilation, production stoppage and / or production release, takes into account (102) measurements of the first measuring device (16) when the separating device (24) is in the first functional state, and takes into account (108) measurements of the second measuring device (20) when the separating device (24) is in the second functional state.