Testing device, especially for pharmaceutical products, with improved measuring quality

Description

State of the art

[0001] The present invention relates to a testing device, in particular for testing pharmaceutical containers for leaks, with a significantly improved measurement quality.

[0002] Particularly in the case of pharmaceutical products that are filled in containers, a leak test must be carried out for medical reasons. In principle, a leak test can be carried out using either positive or negative pressure. For this purpose, a container filled and sealed at normal pressure is placed in a closed chamber, for example under vacuum. A certain period of time is then waited for, and a pressure change per unit of time in the vacuum area of ​​the closed chamber is measured. If the vacuum pressure follows a defined characteristic, this is an indication of a leak-tight container. However, if the vacuum pressure deviates from this, assuming a leak-tight chamber, this is a sign of a leak in the container, because leaks in the container, such as holes or cracks, etc., can be detected., a measurable pressure equalization takes place between the interior of the container and the vacuum chamber. During a leak test with overpressure, if the container is leaking and the test chamber is assumed to be leak-tight, a pressure drop occurs in the chamber because the pressure medium enters the interior of the container via the crack or similar, thus equalizing the pressure. The known methods are designed for individual measurement of containers, but are not suitable for use in pharmaceutical mass production. In order to carry out a test method economically, DE 3925494 A1 discloses the simultaneous testing of several containers in one chamber. However, this gives rise to the problem that if one of the containers is leaking, all of the tested containers that were also in the test chamber must be considered leaking, and all of the containers must be disposed of.However, this is a waste of resources, since if only one of the containers were leaking, the others would actually have been usable. Furthermore, another method for testing containers for leaks is known from US Pat. No. 8544315 B2. Large leaks can be detected relatively well using the known methods. However, detecting very small leaks is often difficult. Furthermore, US 2011 / 174060 A1 A method and apparatus for leak testing liquid and non-liquid-filled rigid and semi-rigid non-porous containers, wherein a container is enclosed in a suitable test chamber and subjected to a vacuum while the pressure within the chamber is monitored by an absolute pressure transducer alone or in combination with a second differential transducer to determine whether leaks exist in the container. Disclosure of the invention

[0003] The testing device according to the invention with the features of claim 1 has the advantage that a container can be tested for leaks in two stages by means of a gross leak measurement and a fine leak measurement, wherein the gross leak measurement can be decoupled from the fine leak measurement. Furthermore, the testing device can be rinsed after a measurement process has been completed, whereby moisture or impurities or heat or the like can be removed from the testing device. As a result, a very high level of precision and, in particular, the highest level of repeatability of a test measurement can be achieved according to the invention. This is achieved according to the invention in that the testing device has a test connection which is designed to be connected to a test chamber in which a container to be tested for leaks is accommodated. The container is preferably a medical container, such asan ampoule or a vial or the like. The testing device further comprises a vacuum source which is connected to the test connection via a first line. The vacuum source is preferably a compressor. The testing device further comprises a first sensor for measuring gross leaks and a second sensor for measuring fine leaks. The first sensor is arranged on the first line and the second sensor is arranged on a second line which branches off from the first line. Furthermore, a third line is provided which branches off from the first or second line and leads to a flushing connection. After the measurement has been taken, the testing device can then be flushed with a flushing medium via the flushing connection. A third valve is arranged in the third line, which opens and closes the connection to the flushing connection.Thus, according to the invention, the problem that contaminants can be introduced into the test device when a container to be tested is placed in the test device can be solved. Furthermore, the gross leak measurement is decoupled from the fine leak measurement so that the arrangements for fine leak measurement are not contaminated. After the gross leak measurement has been carried out, if no gross leak is detected, the fine leak measurement is then carried out, whereby the areas of the test device required for the fine leak measurement are free of contaminants due to the decoupling. After the fine leak measurement has been carried out, flushing can then take place via the flushing connection of the test device so that a clean system is available for the next test. Thus, through the targeted use of several valves, sensitivity during the fine leak measurement can be increased by reducing the reference volume in which the fine leak measurement takes place. In order to achieve the simplest possible structure with few valves, the second line branches off from the first line into an area between the test connection and the second valve.

[0004] The subclaims show preferred developments of the invention.

[0005] Preferably, the first sensor is arranged at the intermediate line region of the first line between the first and second valves.

[0006] The testing device further preferably comprises a defined pre-volume arranged between the first sensor for gross leak measurement and the first line. The defined pre-volume makes it possible to reduce the risk of contamination of the first sensor for gross leak measurement during gross leak measurement. Should a container have a gross leak, the defined pre-volume arranged upstream of the first sensor for gross leak measurement in the flow direction can absorb the contamination, preventing the first sensor from coming into contact with the medium escaping from the container.

[0007] The pre-volume is preferably larger than the volume of the first line.

[0008] Further preferably, the second line, in which the second sensor for fine leak measurement is arranged, opens into the intermediate line area between the first and second valve.

[0009] According to a further preferred embodiment of the invention, the testing device comprises a fourth valve, which is arranged between the third valve and the purge connection and enables a connection to the atmosphere. Thus, a connection to the atmosphere or to a purge medium can be established via the fourth valve. The purge medium is preferably arranged in a purge medium reservoir and is preferably pressurized. This enables rapid purge of the testing device.

[0010] According to a further preferred embodiment of the invention, the testing device further comprises a fifth valve, which is arranged in the second line between the second sensor for fine leak measurement and the first line. The fifth valve enables, particularly during fine leak measurement, the additional volume available for coarse leak measurement to be decoupled during fine leak measurement. This further improves sensitivity during fine leak measurement.

[0011] According to a further preferred embodiment, the testing device further comprises a sixth valve, wherein the sixth valve is arranged in the second line, and the second line forms a loop in which the second sensor for fine leak measurement and the fifth valve are arranged. This embodiment also allows for complete decoupling of the fine leak measurement area of ​​the testing device.

[0012] The test device preferably also includes the test chamber, which has a hollow space for accommodating the container to be tested. The test chamber preferably has a first and second chamber section. The test connection connects the hollow space to the actual measuring arrangements for coarse leak measurement and fine leak measurement.

[0013] Further preferably, the test device comprises a reservoir filled with a flushing medium, which can be connected directly to the cavity of the test chamber or the third line. If the reservoir is connected to the cavity of the test chamber, the cavity of the test chamber can also be easily flushed. This allows contaminants that may enter the test system, for example, when the container to be tested is placed in the test chamber, to be flushed away.

[0014] The device further preferably comprises an atmosphere connection connected to the third line and / or the test chamber. This allows, for example, pressure equalization of the test chamber with air when connected to the test chamber.

[0015] According to a further preferred embodiment, the testing device further comprises a third sensor, which is arranged on the first line between the test chamber connection and the second valve. The third sensor is preferably an absolute pressure sensor. The third sensor can detect a pressure in the cavity of the test chamber, in particular after a measurement has been taken.

[0016] Further preferably, a filter is arranged between the test port and the second valve. This allows the actual test device to be protected from contaminants from the inserted container or a leak in the container.

[0017] The test chamber preferably comprises a first receiving part and a second receiving part. The test chamber is preferably divided into a dividing plane in the longitudinal direction of the test chamber or in the transverse direction of the test chamber.

[0018] Preferably, the first line is arranged on the first receiving part. If the cavity of the test chamber is to be flushed, a flushing connection is preferably arranged on the second receiving part of the test chamber.

[0019] The present invention further relates to a method for testing containers for leaks using a two-stage testing process. The method comprises a gross leak measurement, with which a large leak in the container can be detected, and a fine leak measurement, with which a small leak in the container can be detected. In the method according to the invention, the gross leak measurement is carried out first and, after the gross leak measurement has been carried out and if no gross leak was detected, the fine leak measurement is carried out. After the fine leak measurement has been completed, the container to be tested is removed from the test chamber, and a step of rinsing the test device with a rinsing medium follows in order to keep out contaminants and to flush out any contaminants that may have been present in the test device as a result of the previous measuring process.

[0020] The method according to the invention is particularly preferably used in pharmaceutical containers. drawing

[0021] Preferred embodiments of the invention are described in detail below with reference to the accompanying drawings. In the drawing: Figure 1 shows a schematic view of a testing device according to a first exemplary embodiment of the invention, Figure 2 shows a schematic view of a testing device according to a second exemplary embodiment of the invention, Figure 3 shows a schematic view of a testing device according to a third exemplary embodiment of the invention, Figure 4 shows a schematic view of a testing device according to a fourth exemplary embodiment of the invention, Figure 5 shows a schematic view of a testing device according to a fifth exemplary embodiment of the invention, Figure 6 shows a schematic view of a testing device according to a sixth example not according to the invention, Figure 7 shows a schematic view of a testing device according to a seventh exemplary embodiment of the invention, Figure 8 shows a schematic view of a testing device according to an eighth exemplary embodiment of the invention, and Figure 9 shows a schematic view of a testing device according to a ninth exemplary embodiment of the invention. Preferred embodiments of the invention

[0022] The following is based on reference to Figure 1 a testing device 1 according to a first preferred embodiment of the invention is described in detail.

[0023] As from Figure 1 As can be seen, the test device 1 comprises a test connection 2, to which a test chamber 4 is connected. The test chamber 4 comprises a first chamber part 41 and a second chamber part 42, which define a cavity 40 between them. A container 11 to be tested is arranged in the cavity 40.

[0024] In this embodiment, the container 11 to be tested is a pharmaceutical container that must be tested for leaks. The test chamber 4 can be opened to allow the container 11 to be tested to be inserted into and removed from the volume 40. As can be seen from Figure 1As can be seen, the test chamber 4 is divided longitudinally. The test connection 2 is located on the first chamber part 41.

[0025] The test device 1 further comprises a first line L1, which leads from the test connection 2 to a vacuum source 9. The vacuum source 9 is a compressor and leads to an atmosphere 10.

[0026] A first valve V1 and a second valve V2 are arranged in the first line L1. As a result, the first line L1 forms an intermediate line region ZL1 between the first valve V1 and the second valve V2.

[0027] The testing device 1 further comprises a first sensor 6 and a second sensor 5. The first sensor 6 is intended for coarse leak measurement and is preferably an absolute pressure sensor. The second sensor 5 is intended for fine leak measurement and is preferably a differential pressure sensor.

[0028] As from Figure 1As can be seen, the first sensor 6 is arranged on the first line. More precisely, the first sensor 6 is arranged on the intermediate line area ZL1. As can be seen from Figure 1 As can be seen, a pre-volume 8 is provided between the first sensor 6 and the intermediate line region ZL1. The pre-volume 8 has a volume that is larger than the volume of the first line L1 between the test connection 2 and the vacuum source 9.

[0029] The size of the pre-volume 8 is selected such that the risk of contamination of the first sensor 6 is as small as possible. This means that if, for example, the container 11 to be tested has a leak, the medium present in the container 11 would flow into the first line L1 due to the suction effect of the vacuum source 9 and thus also into the pre-volume 8. Since the first sensor 6 would detect that there is a leak in the container 11 after a relatively short measuring time, the measurement could be aborted without the medium escaping from the container 11, which would contaminate the test device 1, reaching the first sensor 6 and causing severe contamination.

[0030] The test device 1 further comprises a second line L2, which branches off from the first line L1. As can be seen from Figure 1As can be seen, the second sensor 5 is arranged in the second line L2. Furthermore, a third line L3 is provided, which branches off from the second line L2. The third line leads to a flushing connection 3. A reservoir 7 for a flushing medium is connected to the flushing connection 3.

[0031] A third valve V3 is arranged in the third line L3 to open and close a connection to the flushing port 3.

[0032] Furthermore, a fourth valve V4 is arranged in the third line L3, which optionally enables a connection to the reservoir 7 or a connection 70 to an atmosphere 10. This is shown in Figure 1 shown in dashed lines.

[0033] The flushing medium in reservoir 7 can be, for example, dry air, filtered air, or nitrogen. The flushing medium in reservoir 7 is intended to specifically flood the test device 1 with the flushing medium after a measurement cycle and to flush out possible contaminants such as moisture or dust or a leaked medium from the container 11 and / or to keep possible contaminants away from the test device 1 and the test chamber 4.

[0034] It should be noted that for rapid ventilation and subsequent opening of the test chamber 4, the flushing medium can be stored in the reservoir 7 under high pressure, thus enabling sudden flooding of the test device 1. It should also be noted that after the test device has been flooded with the flushing medium from the reservoir 7 or, alternatively, with air, the test chamber 4 can be opened to remove the tested container 11. It must be ensured that a sufficient amount of flushing medium always flows in while the test chamber 4 is open, so that moisture and / or dust and / or other impurities and / or heat or other external influences cannot penetrate the test device 1.

[0035] Since contamination of the test device 1 cannot be completely ruled out when exchanging the container 11 to be tested while the test chamber 4 is open, a targeted rinsing medium curtain and / or aligned rinsing nozzles arranged in the test chamber 4 can also be used. It is also possible to perform an additional rinsing pulse or the like shortly before closing the test chamber 4 after inserting a new container 11 to be tested in order to enable cleaning of the test chamber and the inserted container 11. As a result, shortly before closing the test chamber 4, the cavity 40 of the test chamber is filled with rinsing medium as much as possible to prevent the penetration of moisture and / or contamination and / or the introduction of heat.

[0036] The inventive method for testing an inserted container 11 for leaks is as follows. In a first step, the first and second valves V1 and V2 are opened and the third valve V3 remains closed. The vacuum source 9 is operated so that the medium located in the first line L1 and the second line L2 is sucked out of these lines. Likewise, the cavity 40 of the test chamber 4 is sucked empty. This creates a negative pressure in the cavity 40 of the testing device 1. After the sucking process, the first valve V1 is closed and a gross leak measurement is carried out using the first sensor 6. Should a leak be present in the container 11, the first sensor 6 detects a deviation from the resulting pressure level, in particular a pressure increase in the first line L1, which indicates a large leak in the container 11.A control unit 100 enables a comparison of the recorded pressure values ​​after a predetermined time to determine whether a major leak is present or not.

[0037] If it is determined that there is no major leak, the vacuum source 9 continues to operate so that the testing device 1 can perform a fine leak measurement. For this purpose, the second sensor 5 in the second line L2 detects a pressure profile, in particular a pressure reduction, over time, and the control unit 100 compares this detected pressure profile, in particular a pressure reduction, with stored values. The first and second valves V1 and V2 are closed. In the event of deviations, a fine leak is assumed, and the container 11 is rejected.

[0038] If no fine leak was detected, the container 11 is classified as a leak-free container and passed on for further use. Before the test chamber 4 is opened to remove the container 11, the third valve V3 and the fourth valve V4 are opened. The fourth valve V4 either connects the third line L3 to the reservoir 7 for the pressurized flushing medium or to the atmosphere 10. When the test chamber 4 is then opened, either air flows from the atmosphere 10 into the third line L3 and the rest of the test device 1, or flushing medium flows from the reservoir 7 into the third line L3 and the rest of the test device 1. The vacuum source 9 is preferably not operated in this case. However, it should be noted that it is also possible for the vacuum source 9 to be operated for complete flushing and thus to draw in flushing medium and / or air.

[0039] Regarding the first embodiment, it should also be noted that the control unit 100 also controls the vacuum source 9. The control unit 100 can also control all valves of the test device 1, whereby for reasons of clarity Figure 1 no such control lines are shown.

[0040] It should also be noted that to ensure the test device 1 is as clean as possible, the test chamber 4 should be kept closed prior to use of the test device 1. The test chamber 4 can either be placed under vacuum or, preferably, flushed beforehand with the flushing medium from the reservoir 7. This ensures that as little moisture, contamination, or the like as possible enters the test device 1. This also significantly reduces the lead time for resuming a measurement cycle.

[0041] Figure 2shows a test device 1 according to a second embodiment of the invention. In contrast to the first embodiment, the test device 1 of the second embodiment has a fifth valve V5. The fifth valve V5 is arranged in the second line L2. As can be seen from Figure 2As can be seen, the second line L2 branches off from the first line L1 from an area between the test connection 2 and the second valve V2. The second line L2 then flows into the intermediate line area ZL1 between the first valve V1 and the second valve V2. The fifth valve V5 is arranged between the second sensor 5 and the intermediate line area ZL1. The fifth valve V5 enables, in particular, a separation of the second line L2 from the first line L1 during gross leak measurement. Furthermore, the fifth valve V5 enables an increase in sensitivity during fine leak measurement by reducing the volume, since in particular the pre-volume 8 is decoupled during fine leak measurement. A further advantage is that the pre-volume 8 can also be pre-evacuated during fine leak measurement by the operated vacuum wave 9, whereby the cycle time can be significantly reduced.

[0042] During the gross leak measurement, the first valve V1 and the fifth valve V5 are closed. The second valve V2 is opened. This unites the cavity 40 of the test chamber 4 with the pre-volume 8, and a gross leak measurement can be performed using the first sensor 6, which is designed as an absolute pressure sensor. After the gross leak measurement, the first valve V1 is opened so that the cavity 40 of the test chamber 4 can be evacuated, while the valve V3 remains closed. Afterward, the second valve V2 and the fifth valve V5 can also be closed. The fine leak measurement can then be performed using the second sensor 5.

[0043] Figure 3shows a testing device 1 according to a third exemplary embodiment of the invention. The third exemplary embodiment essentially corresponds to the second exemplary embodiment, wherein, in contrast to the second exemplary embodiment, the second valve V2 and the fifth valve V5 are designed as a double valve. The second valve V2 and the fifth valve V5 are mechanically coupled to one another by means of a coupling element 12. As a result, the second valve V2 and the fifth valve V5 can be blocked or unlocked simultaneously with one switching movement. Thus, the second valve V2 and the fifth valve V5 can each be kept in the same state, i.e., open or closed, for the gross leak measurement and / or the fine leak measurement.

[0044] Figure 4shows a testing device 1 according to a fourth embodiment of the invention. The fourth embodiment essentially corresponds to the second embodiment, with the second line L2 in the fourth embodiment opening into the first line L1 in the area between the test connection 2 and the second valve V2. The second line V2 also branches off from the first line L1 into this area between the test connection 2 and the second valve V2.

[0045] Figure 5shows a testing device 1 according to a fifth exemplary embodiment of the invention. The fifth exemplary embodiment is based on the first exemplary embodiment, wherein, in contrast to the first exemplary embodiment, in the fifth exemplary embodiment the second line L2 branches off from the first line in a region between the test connection 2 and the second valve V2 and opens again at the same point. The second line L2 has a closed circuit in which the second sensor 5 and a fifth valve V5 are arranged. A sixth valve V6 is arranged in the common supply and return line (see Figure 5). In this configuration according to the fifth exemplary embodiment, it is thus possible for the fine measuring sensor to be completely decoupled by the sixth valve V6. Thus, during the gross leak test, the second sensor 5 can be decoupled by closing the sixth valve V6. The sixth valve V6 can thus be opened at a time when a pressure level suitable for the fine leak measurement is reached during the evacuation. Thus, the fifth and sixth valves V5, V6 can be opened while the evacuation is still taking place. When the cavity 40 is then decoupled via the second valve V2, the fifth valve V5 is closed following the start of the fine leak measurement. After the end of the fine leak measurement, the sixth valve V6 should then be closed again before venting so that the second sensor 5 can always be kept under vacuum.In this embodiment, the second valve V2 first ensures the coarse leak test and then the second valve V2 seals off the defined pre-volume 8 during the fine leak measurement, thereby achieving a significant increase in the sensitivity of the fine leak measurement.

[0046] Figure 6 shows a testing device according to a sixth example, wherein the sixth example essentially corresponds to the fifth embodiment. In the sixth example, a closed circuit is also provided for the second line L2, in which the second sensor 5 and the fifth valve V5 are arranged. In contrast to the fifth embodiment, the common branching and opening of the second line L2 in the sixth example takes place in and out of the intermediate line region ZL1 between the first valve V1 and the second valve V2. Otherwise, this example corresponds to the fifth embodiment.

[0047] Figure 7shows a test device 1 according to a seventh embodiment of the invention. As can be seen from Figure 7 As can be seen, the reservoir 7 for the flushing medium in the seventh embodiment is directly connected to the cavity 40 in the test chamber 4 via a second flushing connection 30. In this case, a seventh valve V7 is arranged between the reservoir 7 and the cavity 40. The third valve V3 is provided for establishing and interrupting a connection to the atmosphere 10. The seventh embodiment enables the air-filled cavity 40 of the test chamber 4 to be optimally flushed by means of a flushing medium from the reservoir 7 by using an additional seventh valve V7 after closing the test chamber 4. As can be seen from Figure 7As can be seen, a connection for the reservoir 7 is provided on the second chamber part 42 of the test chamber 4. This enables the air present in the volume 40 of the test chamber 4 to be exchanged with the flushing medium.

[0048] Figure 8 shows a test device 1 according to an eighth exemplary embodiment of the invention, which essentially corresponds to the seventh exemplary embodiment. In the eighth exemplary embodiment, only the connection to the atmosphere 10 and to the reservoir 7 for the flushing medium are interchanged. In other words, a seventh valve V7 is provided, which establishes and interrupts a connection to the atmosphere 10 via the second chamber part 42 of the test chamber 4. The reservoir 7 for the flushing medium is arranged at the flushing connection 3, which is controlled via the third valve V3. Otherwise, this exemplary embodiment corresponds to the seventh exemplary embodiment. Furthermore, the seventh valve V7 can be switched actively or passively.

[0049] Figure 9 shows a test device 1 according to a ninth embodiment of the invention. The ninth embodiment is based on the fifth embodiment, in which the second line L2 is connected to the first line L1 as a closed line. Here, the arrangement for fine leak measurement can be completely decoupled from the coarse leak measurement by the sixth valve V6. As can be seen from Figure 9As can be seen, the cavity 40 of the test chamber 4 is connectable to the atmosphere 10 via the seventh valve V7. The test chamber 4 is not divided in the longitudinal direction of the test chamber by the two chamber parts 2, 3, as in the other exemplary embodiments, but in the transverse direction. Furthermore, a filter 14 is provided, which is arranged between the test connection 2 and the branch of the second line L2. The ninth exemplary embodiment further comprises a third sensor 13, which is arranged on the first line L1. The third sensor 13 is an absolute pressure sensor for measuring a pressure in the cavity 40 of the test chamber 4. This has the advantage in the gross leak measurement that a pressure in the individual volume of the gross leak measurement can be measured by the third sensor 13 and the first sensor 6. This allows a calibration of the first sensor 6 and the third sensor 13. As can be seen from Figure 9As can be seen, for gross leak measurement the second valve V2 is opened and the first valve V1, the third valve V3, the sixth valve V6 and the seventh valve V7 are closed.

[0050] In the ninth embodiment, the second sensor 5 is designed as a differential pressure sensor. However, it should be noted that the second sensor 5 can also be provided as an absolute pressure sensor or a relative pressure sensor. In this case, the seventh valve V7 is not necessary.

[0051] The fourth valve V4 is designed as a three-two-way valve.

[0052] It should also be noted that by closing the second valve V2 during the fine leak measurement, the preliminary volume 8 for the coarse leak measurement can also be evacuated, preferably by a vacuum source 9. This saves time for the measurement of the next container 11. The sixth valve V6 is not absolutely necessary in this exemplary embodiment, but is preferably provided to keep the second sensor 5 clean. While the test chamber 4 is open, it is also possible for flushing medium to constantly flow from the reservoir 7 by opening the third valve V3 and the fourth valve V4 in order to keep all external influences away from the measuring system as far as possible.

[0053] For all embodiments, it should also be noted that it is also possible for nozzles to be provided on the test chamber 4 in order to rinse the cavity 40 of the test chamber 4 by means of a targeted rinsing pulse shortly before the test chamber is closed in order to remove possible contaminants from the test chamber 4.

[0054] It should also be noted that, for all embodiments, for accurate measurement results, the pressure in the test chamber 4 should, as far as possible, correspond to the ambient pressure after closing the test chamber 4. This can be achieved, for example, by connecting the cavity 40 of the test chamber to the atmosphere via the seventh valve V7 or via the third and fourth valves V3, V4.

Claims

1. A test device comprising: - a test port (2) which is configured to be connected to a test chamber (4) in which a container (11) to be tested for leaks is housed, - a vacuum source (9) which is connected to the test port (2) via a first line (L1), - a first valve (V1) and a second valve (V2), which are arranged in the first line (L1), wherein the first valve (V1) is arranged upstream of the second valve (V2) starting from the vacuum source (9), wherein the first line (L1) has an intermediate line region (ZL1) between the first valve (V1) and the second valve (V2), - a first sensor (6) for a coarse leak measurement, which is arranged on the first line (L1), - a second sensor (5) for fine leak measurement, - a second line (L2) which branches off from the first line (L1), wherein the second sensor (5) is arranged in the second line (L2), - a third line (L3) which branches off from the first line (L1) or the second line (L2) and leads to a flushing port (3), and - a third valve (V3) which is arranged in the third line (L3) in order to open and close the connection to the flushing port (3), characterized in that the second line (L2) branches off from the first line (L1) in a region between the test port (2) and the second valve (V2).

2. The test device according to claim 1, wherein the first sensor (6) is arranged at the intermediate line region (ZL1).

3. The test device according to any of the preceding claims, further comprising a defined pre-volume (8) which is arranged between the first sensor (6) and the first line (L1).

4. The test device according to any of the preceding claims, wherein the second line (L2) opens into the intermediate line region (ZL1) between the first valve (V1) and the second valve (V2).

5. The test device according to any of the preceding claims, further comprising a fourth valve (V4) which is arranged on the flushing port (3) in order to make possible a connection to the atmosphere (10) or a connection to a reservoir (7) for a flushing medium.

6. The test device according to any of the preceding claims, further comprising a fifth valve (V5) which is arranged in the second line (L2) between the second sensor (5) and the first line (L1).

7. The test device according to any of the preceding claims, further comprising a sixth valve (V6), which is arranged in the second line (L2), wherein the second line (L2) forms a closed loop in which the second sensor (5) is arranged.

8. The test device according to any of the preceding claims, further comprising a third sensor (13) which is arranged on the first line (L1) between the test port (2) and the second valve (V2).

9. A method for checking containers (11) for leaks, comprising the steps of: - placing the container to be tested (11) in a sealable test chamber (4), - generating a negative pressure in the test chamber (4), and - performing a coarse leak measurement to determine whether the container (11) has a large leak by means of a first sensor (6), which is arranged on a first line (L1), - if the large-plate measurement has not detected a leak in the container (11), performing a fine leak measurement by means of a second sensor (5), which is arranged in a second line (L2), - wherein the first line (L1) connects a vacuum source (9) to a test port (2), which is configured to be connected to the test chamber (4), - wherein the second line (L2) branches off from the first line (L1), - wherein, prior to performing the coarse leak measurement, the test device is flushed with a flushing medium in order to keep the test device (1) free from contamination and external influences, in particular heat influences, characterized in that the method is performed with a test device according to any of the preceding claims.