KR20010012990A - Method and apparatus for leak testing - Google Patents

Abstract

In order to leak test a closed container 9 containing a fill product containing at least one liquid component, the container is put into a test cavity 1 which is vacuum suctioned to at least the vapor pressure of the liquid component. The pressure around the container 9 and therefore the pressure inside the test cavity 1 is monitored. The monitoring is carried out by the vacuum pressure sensor 7, while the drop in the pressure surrounding the container 9 is performed by the vacuum pump 5. Leakage of the vessel is detected by monitoring the pressure change around the vessel due to the evaporation of the liquid coming out of the leak port and evaporating around the low pressure.

Description

Leak Test Method and Apparatus {METHOD AND APPARATUS FOR LEAK TESTING}

Leak test techniques are known, in which a sealed container is placed inside a test cavity and the test cavity is hermetically sealed and the pressure is reduced by a suction pump. If the container does not leak, this pressure will remain nearly constant once the predetermined pressure within the inspection cavity, ie around the container to be inspected, has reached a predetermined pressure. If there is a leak in any area where the air in the vessel is trapped, the air flow from the vessel will cause an increase in ambient pressure. If leakage exists in the area where the filled product in the container is confined, whether such leakage will result in a significant rise in ambient pressure depends largely on the type of filled product, such as its viscosity, the presence of solid particles in the filled product, Of course, it also greatly depends on the size of the leak port.

Various approaches have been known for accurately finding leaks in vessels filled with products regardless of whether the leaks exist in areas of enclosed containers or in areas covered with filling material. One such approach is the concurrent European patent application EP-A-0 791 814 and US patent application no. It is the subject of 08/862993, which proposes to provide impedance measurements, in particular resistance measurements, near the vessel outer wall by any electrode arrangement. That is, when the liquid seeps out of the leak port, it comes into contact with each pair of impedance measuring electrodes, causing a significant change in the impedance measured between the electrodes.

Nevertheless, such an approach requires considerable additional expense associated with providing a device for impedance measurement inside the inspection cavity of each inspection cavity, in particular a multi-cavity in-line inspection machine, It does not make it possible to detect leak openings that are much smaller than one micron and are almost independent of the shape of the container and the type of filling product.

[Purpose of invention]

It is a primary object of the present invention to provide a leak test method and a leak test device which can be applied to a wide variety of containers and various filled products having at least one liquid component.

It is a further object of the present invention to provide a leak test method and a leak test device which is relatively inexpensive and thus very economical in connection with electronic and further devices.

It is a further object of the present invention to provide a leak test apparatus and a leak test method which have a short measuring cycle and nevertheless have very high measurement accuracy.

In general, the present invention relates to a technique for inspecting leakage of an airtight container filled with a fill material comprising at least one liquid component.

The present invention will now be further described with the aid of figures showing specific presently preferred embodiments of the invention.

1 qualitatively shows the dependence of the vapor pressure on the temperature of the liquid.

2 is a schematic view of the inspection apparatus of the present invention operating in accordance with the method of the present invention.

Figure 3 qualitatively shows the path over time of the pressure around the container to be examined by the present invention to illustrate the method and apparatus operation of the present invention.

4 shows a functional block diagram of a preferred form of implementation of the testing device of the present invention operated by the present invention.

FIG. 5 shows, as a functional block diagram, an implementation of a preferred form of an electronic device evaluated in a device of the present invention for performing the method of the present invention.

6 shows diagrammatically a layout operation of the device of the invention.

7 shows diagrammatically a test cavity for inspecting a container with a flexible wall.

8 shows in perspective view a half of an inspection cavity for inspecting three containers in accordance with the invention in one arrangement;

9 is a diagrammatic representation of a double wall tank used directly to implement the method of the present invention with the apparatus of the present invention for inspecting tank leakage.

10 is a schematic representation of a preferred seal in an inspection cavity of the device of the present invention.

11A-11C show paths of pressure in test cycles, in which containers or medical application blisters leak large or very large (FIG. 11A), or have only a small leak (FIG. 11B). ), Or it does not leak (FIG. 11C). The tests are done with test cavities according to FIG. 8 without impedance measurement and therefore without electrodes 32, 34.

12 shows a signal flow / functional block diagram of a simplified preferred embodiment of an evaluation device for operating with the method of the invention in the device of the invention.

FIG. 13 shows a statistical deviation of pressure paths measured in leak free vessels or in test cavities without any vessels in a diagram of pressure versus time. FIG.

FIG. 14 illustrates a simplified functional block / part of a device of the present invention which operates in accordance with a preferred mode of the method of the present invention and thereby generates a dynamic reference value by subsequently updated averaging. The diagram shown in the signal flow diagram.

15 shows qualitatively in a simplified signal versus time diagram the operation of the preferred method of the present invention and thus the preferred apparatus of the present invention in which dynamically updated reference values are generated for leak checking.

FIG. 16 is a simplified signal flow / functional block showing an additional preferred mode of operation of the present invention and an apparatus of the present invention in which a dynamically updated average signal is generated as a basis for a reference value to be compared with a pressure differential signal evaluated during vessel inspection. Degrees showing degrees.

FIG. 17 shows a dynamic update of an average signal in which reference values for comparison determine leakage based thereon, with pressure measurements being plotted on the time axis in subsequently operated test cavities of the device of the invention having multiple cavities. Degrees shown in arbitrary units.

18 is a schematic representation of one inspection cavity in accordance with the present invention being rotated during inspection.

FIG. 19 shows the effect on the relative position of the leak opening with respect to the filled product of rotating the inspection cavity according to FIG. 18. FIG.

FIG. 20 shows a simplified functional view of the provision of a calibration standard leak for calibrating the device of the present invention when performing the method of the present invention. FIG.

In order to achieve the above objects, a method for leak testing at least one filled and hermetically sealed container, wherein the contents of the container include at least one liquid component, and at least a pressure difference is applied across the portion of the container wall to be leak tested. The applied pressure difference is directed towards the vessel and the pressure around the vessel is monitored as a leak indication signal, the pressure difference being at least equal to the vapor pressure of the at least one liquid component of the fill product of the vessel to be inspected. There is provided a leak inspection method, which is made by lowering the value accordingly.

The present invention starts from the recognition that if a container leaks and the liquid is drawn out by low ambient pressure-at a constant ambient volume-as soon as the ambient pressure reaches its vapor pressure, the liquid evaporates. This results in a significant change in the ambient pressure when compared to the ambient pressure produced under the same measurement conditions as a leak-tight container.

Once the vapor pressure of the leakable liquid has been reached, monitoring the pressure in the test cavity containing the container has been found to be a very accurate technique for leak testing. It has been noted that such a technique can accurately detect leakage of a container for a very wide range of filled products and that leak openings up to 0.02 μm can now be detected accurately.

Furthermore, it has been noted that the volume of the test cavity is not critical so that it is possible by the technique of the present invention to simultaneously inspect the batches of containers and accurately detect whether one of the container batches is leaking.

As soon as the pressure surrounding the leaking vessel is lowered relative to its internal pressure, some of the liquid is sucked out of the vessel and begins to evaporate as soon as the ambient pressure reaches the vapor pressure. When the liquid evaporates in a constant volume of the surrounding area surrounding the vessel, an increase in pressure and a pump that lowers the ambient pressure must now remove the vapor of the liquid, so that in particular the surrounding pressure of the vessel will be lower than the vapor pressure. Significant measurements can be made later. Nevertheless, it is preferred to provide a pumping capacity which draws the periphery of the vessel to be inspected at a value significantly lower than the vapor pressure, ie at least two decades, preferably even at least three decades. .

Leak significant pressure change, meaning leakage, can be detected as soon as one of several possible liquid components of the fill product begins to evaporate-if the contents of the container contain one or more liquid components. It is recommended to select the higher of the vapor pressures of the two liquid components to lower the pressure around the vessel to at least that vapor pressure.

As is well known, the vapor pressure is a function of temperature and thus it may be advantageous in some cases, for example, to heat the surroundings of the vessel to a predetermined temperature in order to create an associated vapor pressure for the predetermined liquid, but the method and apparatus of the present invention. Is considerably less complicated when the test is carried out at room temperature and thus at least the vapor pressure that must be reached is considered at room temperature, ie near 20 ° C.

Furthermore, if the pressure around the vessel is measured at two successive points in time, very accurate leak detection is possible, where "point" is understood to be the time interval required to accurately measure the dominant pressure. Although it is absolutely possible to realize the leak detection by applying the pumping action of the vacuum pump around the vessel and then measuring the resulting ambient absolute pressure after a predetermined time interval, the above mentioned measurement of the ambient pressure at two specific time points The measurement allows using the first measured value as a reference value and then generating a difference of the second measured value to that reference value. Thereby, the pressure difference is measured instead of the absolute pressure measurement. More specifically, the first pressure signal measured at the first time point is stored as an electrical signal, and after measuring the second pressure value, a difference between the first and second values still stored is generated.

International patent application WO94 / 05991, assigned to the same applicant as the applicant of the present invention, together with its corresponding US patent 5 239 859, describes a method and apparatus for highly precise offset-compensated pressure differential measurements. In a preferred embodiment of realizing the apparatus of the invention and in a preferred embodiment of the method according to the invention, the pressure differential measuring technique and apparatus are used. Therefore, WO94 / 05991 or related US Pat. No. 5 239 859, although most important features are also specifically described in this application, as will be shown in the future, are fully incorporated herein by reference.

Since how large the surrounding volume of the test cavity for the container is in terms of the volume of the container to be inspected is usually not important, the method and apparatus of the present invention is found to have the following additional important advantages.

If the wall of the at least one vessel to be inspected withstands the pressure difference between the vessel internal pressure (typically ambient pressure) and the lowered ambient pressure, then such vessel is almost independent of how large it is with respect to the test cavity. It can simply be introduced into the inspection cavity forming the perimeter. Nevertheless, a very accurate indication of leakage can be obtained by the present invention. Therefore, the same one inspection cavity can be used for different volumes of containers with different dimensions. This is because one or more batches of several vessels are introduced into one inspection cavity forming a perimeter and although one vessel occupies only a portion of the total cavity volume, if one vessel of the vessel batch is ambient atmosphere Leakage at this point has the additional advantage that an accurate leak indication can be detected.

Further important advantages of the present invention are as follows.

Sometimes a filled container is not fully filled and some amount of air is trapped inside the closed container. If there is a leak opening in the area near the trapped air or gas of such a container, such air will be sucked out of the container through the leak opening by lowering the ambient pressure. As the pressure of the trapped air in the vessel is gradually lowered, evaporation of the liquid component inside the vessel will also begin and such vapor will also escape through the leak port. The air exiting through the leak port, and then the steam exiting through the leak port, increases the ambient pressure so that the leak port in the area where the air is trapped is as if the leak port is in the container wall covered with liquid contents, This results in a change in the ambient pressure, ie an increase in the ambient pressure. Thus, by appropriately setting threshold values for leak opening detection in accordance with the minimum or still permissible pressure changes, whether such leak openings are present in the container area covered with air or in the container area covered with the contents. It doesn't matter if it exists.

If the ambient pressure change that occurs when the same leak port is in an air-tight area of the container is less than the pressure change that would result if the same leak port is located in a liquid-covered area, It is such a pressure change that will govern the setting of the threshold for detection. Conversely, if the ambient pressure change when there is one and the same outlet in the liquid-covered area is less than the ambient pressure change when such a leak is in the wall region in contact with the air, the container leaks. Dominating the threshold setting for detecting whether it is likewise a smaller pressure change.

If the vessel under test leaks significantly, as soon as such a leak is detected, to prevent the contents of the vessel from contaminating inside the inspection cavity or, in general, around the vessel and possibly even the pumping facility, absolutely unavoidable Lowering the ambient pressure must be stopped. This can be realized by monitoring whether the pumping action results in a drop in a predetermined ambient pressure, or by the impedance, preferably by measuring the DC resistance around the vessel immediately near the vessel wall to be inspected. It can detect that it spreads around this. This is realized by providing an electrode arrangement around the immediate vicinity and at least near the portion to be inspected of the container. When the filling contents of the container are sucked into its outer wall, the electrode arrangement is connected by such contents, which causes an abrupt change in impedance, which stops lowering the pressure around the container further after it is detected. To be used.

The latter technique of quickly detecting large leak openings is particularly applicable to containers where the applied pressure differential cannot be tolerated by the wall and needs to be snugly encapsulated within the test cavity. In such a case an electrode arrangement for impedance measurement can be integrated along the inner wall of the test cavity, the inner wall snugly fits with the at least one container. If such a container is intended to be inspected and the test cavity thus fits snugly into its shape, nevertheless, by providing a supporting grid or mesh inlay to define the perimeter of the container, Preferably by roughening the inner wall of the test cavity such that a plurality of micro-embossments of the test cavity wall support the container wall, a continuous space is maintained between the outer wall of the container and the wall of the test cavity. This prevents the container wall from further bending out due to the applied pressure differential. Thus, the space of mutual interaction between such reliefs defines the space around the container.

If it is detected that the container inside the test cavity is leaking in the test cavity defined for the perimeter of the container, there is a possibility that such test cavity is contaminated by some of the contents of the container. Such cavities are then cleaned after the leaking vessel has been removed, either by vacuum or by flushing with flushing gas, preferably with nitrogen, by heating or for example heated. By combining these techniques as with a flushing gas.

If the method or apparatus of the present invention is applied for inline inspection containers so that two or more of the methods and each device of the present invention operate side by side on a set of containers and one of them is detected as leaking, Each test cavity defined for its surroundings is no longer filled with a container and remains empty in the next measurement cycle, and other cavities are cleaned and reconditioned using a cycle in which the test cavity is in test condition. . Furthermore, in some cases it is proposed to accelerate the squeeze out of the liquid by applying a mechanical force to the wall of the vessel in the presence of a leak opening, raising its internal pressure above atmospheric pressure.

To achieve this object, the present invention provides a leak test apparatus for leak testing at least one sealed and filled container having contents comprising at least one liquid component, the leak test apparatus comprising: at least one sealed sealed test cavity; At least one vacuum suction pump operatively connected to the test cavity and additionally at least one pressure sensor operatively connected to the test cavity, the vacuum suction pump at least Vacuum pressure, selected to be capable of pumping the test cavity at about room temperature to the vapor pressure of the liquid component of the container contents, wherein the pressure sensor preferably comprises at least one Pirani sensor stage We propose a leak tester that is a sensor.

Preferred embodiments of the method and the device of the invention are claimed in dependent claims 2 to 44 and 45 to 63 respectively. The method and apparatus of the present invention can preferably be used as defined in claims 64 and 65. Thus, in addition to leak-checking smaller containers, the present invention continuously monitors the robustness of huge tank plants, for example for gasoline, gas, etc., for example on trains or road vehicles, thus alerting as soon as a leak is detected. It should be indicated that it is possible to generate a signal.

In FIG. 1 the trend of vapor pressure p _V (T) is qualitatively shown in the pressure versus temperature plot. At a predetermined temperature T _X the liquid starts to evaporate when the corresponding vapor pressure p _VX is reached. Above the vapor line the substance is a liquid and below it is a gas.

According to FIG. 2 one device of the present invention comprises an inspection cavity 1 with a lid 3 which can be hermetically sealed. A vacuum pump 5 is connected to the test cavity 1, which may be a drag pump or a rotary piston valve pump or a turbo vacuum pump such as a diffusion pump or a turbo molecular pump. This depends on the degree of vacuum to be established inside the cavity 1. In addition, a vacuum pressure sensor 7 is provided which measures the prevailing pressure inside the inspection cavity 1, for example a piranha sensor. At least one sealed container 9 filled to at least to some extent with a filling product containing at least one liquid component is introduced into the inspection cavity 1 through an open lid 3 and the inspection cavity is then sealed. To be sealed. By the operation of the vacuum pump 5 the pressure of the volume V around the container 9 and therefore between the test cavity and the container 9 is lowered.

According to FIG. 3, starting at ambient pressure p _o , the pressure in the volume V is lowered to a value p _V at least corresponding to the vapor pressure of the liquid component inside the fill product of the container 9. It may be advisable to select a vacuum pump 5 capable of pumping the test cavity 1 to a pressure at least one, preferably two and more preferably three positions lower than the vapor pressure p _V of the liquid contents of the fill product. .

The test is preferably carried out at room temperature. That is, the inspection is carried out at a temperature T of about 20 ° C. If the liquid component is water, the vapor pressure p _V at room temperature of the water is about 20 mbar and then it is desirable to provide a vacuum suction pump 5 capable of drawing the test cavity to about 10 ⁻² mbar.

If the container with the relatively rigid wall 11 provided in the inspection cavity 1 does not leak, the pressure in the volume V is qualitatively lowered along the path a in FIG. 3, by the type of vacuum pump installed. To reach a somewhat constant pressure value that is reached. On the other hand, if the container 9 is leaked as shown schematically in FIG. 2, for example at position 13, a small amount 14 of the liquid component of the fill product may pass through the leak opening 13. As soon as the pressure pulled out and dominating the volume (V) becomes p _V , it begins to evaporate into the volume (V). As qualitatively shown in FIG. 3 this creates a pressure versus time path according to (b), i.e. the evaporation of the liquid results in a pressure rise in the volume (V), which acts against the action of the vacuum pump (5). do. The vacuum pump 5 will have to further remove the vapor in order to finally achieve the vacuum level along path (a). If the leak port is located in the region of the air confined container 9 as shown in 13 'in Fig. 2, the vacuum suction of the volume V first draws the air out of the container, which also acts against the action of the vacuum pump 5 Then, the liquid contents inside the vessel 9 will begin to evaporate inside the vessel and steam will be withdrawn from the leak port 13 '. This will also result in a pressure rise of the volume V, which will act against the pressure path which would have been the case if only air had to be removed by the vacuum pump 5.

The pressure path inside the volume V is monitored by the vacuum sensor 7. The path (a) of FIG. 3 after a time span τ of a few seconds (one to three seconds) and at a less than 1 micron (0.02 μm) leak opening, almost independent of the size of the volume (V) in the test cavity Significant differences in pressures along and path (b) are reached, in which case the pressure difference between the leaking vessel and the non-leaking vessel is about one decade. Measurements were made with water as the liquid component.

It is, of course, possible to measure the absolute pressure in the volume V after a period of time τ for checking the leakage of the container, but for checking the leakage of the container, as will be described first with reference to FIG. 4. , Pressure difference measurement is preferred.

Returning back to FIG. 2, the pressure sensor 7 is usably connected to an evaluating unit 15, in particular in the evaluation device by means of a presetting unit 17 shown schematically. Thresholds indicating leakage are preset. The output of the evaluation device 15 is a two-state signal indicating leakage or noisy.

According to FIG. 4, the output of the vacuum sensor 7 is input to the storage device 19, which is controlled and input by the timing control signal s ₁ as schematically shown by the switch S. FIG. According to FIG. 3 this is done at the first time point t ₁ . At a second time point t ₂ of FIG. 3, the output of the storage device 19 and the output of the sensor 7 are connected to the individual inputs of the difference generating device 21, and the difference generating device is the pressure difference Δ of FIG. 3. Generate an output signal that matches p.

Furthermore, the most preferred embodiment of the evaluation electronic is shown in FIG. 5. The output signal of the sensor 7 is input to the conversion device 121, which includes as an input step an analog to digital converter 121a followed by a digital to analog converter. The output of the converter stage 121 is fed to a difference amplifier unit 123, which additionally receives an output signal from the sensor 7 directly. The output of the difference amplifier device 123 additionally acts on the amplifier device 125, according to the difference device 21 of FIG. 4, whose output is superimposed on its input by the storage device 127 at 128. . The input of storage device 127 is fed from the output of device 125. The timer device 129 times the equipment. In order to store the first pressure value from the sensor 7, according to time t ₁ in FIG. 3, the timer device 129 enables a conversion cycle in the device 121, thus reconverting the analog output. Let the signal el _o appear at the output. At the same time, a nearly identical signal from the sensor 7 is applied as signal el to the second input of the device 123. Thus, at the output of the device 125, a zero signal must appear. Nevertheless, a zero-offset signal will generally appear at the output of device 125, which is stored in storage 127, which is enabled by timing device 129. At time t ₂ no conversion is triggered at the device 121 such that the dominant pressure at time t ₂ appears at the input of the amplifier 123 directly from the sensor 7 and from step 121 the dominant at t ₁ The stored pressure value appears at the input of the amplifier. Further, the zero offset signal stored in the device 127 is superimposed as an offset-compensating signal such that the resulting signal at the output of the amplifier device 125 is zero offset compensated.

This allows a very accurate measurement of the pressure difference Δp according to FIG. 3.

If the vessel under test has a large leak opening, then the dominant pressure in the volume V of the test cavity 1 according to the path (c) of FIG. 3 is different from the beginning of the operation of the vacuum pump 5. Will have This can be easily detected, for example, by comparing the output signal of the sensor 7 with a predetermined threshold (not shown) at a preceding time t ₀ in time, if such a threshold is not reached by the actual pressure. If not, the effect on the test cavity 1 of the vacuum pump 5 is disabled. This is to prevent a large amount of container contents from being sucked into the inspection cavity and contaminating the cavity by the large leak openings.

As mentioned above, the proposed method functions almost exactly regardless of the volume V between the test cavity 1 and the at least one container. This allows, according to FIG. 6, to simultaneously inspect the batches 9 ′ of the containers 9, thereby determining the accuracy of finding whether one or more of the containers 9 leaks. Keep it. Furthermore, the fact that the detection accuracy is not affected with respect to the difference volume V leads to the possibility that a number of containers 9 with different shapes and with different volumes can be inspected within one inspection cavity 1. .

If the wall of the vessel to be inspected does not mechanically withstand a pressure load of about 1 bar, then the lid 3 ', which snugly fits the shape of the vessel 9, as shown schematically in FIG. An inspection cavity 1 'is provided. There, as shown schematically in FIG. 7, the projections 20 prevent the walls of the container from being sucked firmly onto the inner wall of the test cavity by the effect of vacuum suction and thereby between the container and the test cavity wall. To ensure that the volume V for vacuum suction remains. Such protrusions 20 are mesh or grid inlays or, preferably, mechanically roughening the inner wall of the cavity so that micro-embossments support the wall of the container and thereby volume. This is realized by leaving a continuous interspace such as (V).

As shown by the dashed lines in FIG. 7, for example, when covering the lid 3 or 3 ′ of the cavity, a mechanical force is applied inward to a portion of the vessel wall to increase the internal pressure of the vessel 9 and the liquid of the fill product. It may be more advantageous to pressurize the component further and to exit through the leak opening if present.

According to FIG. 9 the method and apparatus according to the invention can be used to monitor huge tanks for leakage. In FIG. 9 a tank having a double wall, ie an inner wall 23 and an outer wall 25 is shown. Checking the tightness of both of these walls is done using the volume in the middle of the two walls, as in the volume V in FIG. 2. Such a technique can be applied, for example, for tanks on road vehicles or rail vehicles or for huge fixed tank plants for example gasoline.

In FIG. 8 a half 1a of an inspection cavity 1 for applying the method of the invention to the apparatus of the invention placing three containers, such as small plastic containers for medical instruments, is shown. The containers can have flexible walls while the test cavity 1 snugly fits their shape. Another technique is further shown for quickly discovering whether one of the containers has a large leak opening. Impedance measuring electrodes 32, 34 are provided integrated into the wall of the cavity 1 and electrically disconnected from each other. They are connected to an impedance or, preferably, resistance measuring device 35. If the liquid filling contents are sucked out of the vessel wall by applying a vacuum to the inspection cavity, preferably having a roughened inner wall, it is measured between the electrodes 32, 34. It is quickly detected by a sudden change in the impedance. The output of the impedance measuring device 35 disables further vacuum suction of the test cavity 1.

Once the test cavity is contaminated by the filling product pouring out of the leaking container, the test cavity is cleaned by cleaning vacuum suction and / or by pouring and / or heating a gas, preferably nitrogen. In FIG. 8 a supply line for flushing gas to cleaning gas is shown, which is controllably fed from the gas tank 37 to the contaminated test cavity 1 and is preferably nitrogen. The two halves of the cavity 1a in FIG. 8 are covered with one sealed in the other to complete the inspection cavity 1 in FIG. 2.

If in-line testing of the vessels is to be carried out, the present invention is particularly suitable because of the short measuring cycle, in which one or more sets of several test cavities are provided, for example, on a carousel. The containers to be inspected (not shown) are automatically loaded from the conveyor and they simultaneously perform the described inspection technique. If one of the containers inspected in such a cavity is detected to leak, then the associated cavity is not subsequently subjected to additional container loading and remains empty during the measurement cycle for the next set of containers. On the other hand, the cavity kept unloaded is cleaned by vacuum suction and / or gas flushing and / or heating, as described above.

Naturally, a good seal should be realized which does not leak vacuum between the cover 3 or 3 'of the inspection cavity and the body of the inspection cavity 1 or between the two halves 1a of the inspection cavity in Figure 8. This is desirable. Preferably, as shown in FIG. 10, by providing at least one pair of side-by-side seals 28 such as concentric O seals and pumping the intermediate space 29 between such seals separately. If the vessel to be tested contains a fill product having two or more kinds of liquid components, the vapor pressure of the liquid component having the highest vapor pressure, ie, the liquid component that begins to evaporate at a relatively highest pressure, leaks. In this regard, the viscosity must also be taken into account, ie through the small leak openings the component must be selected to define the vapor pressure. As to be sufficient for liquid ingredients. By that a considerably lower pressure to the vacuum suction of all the vapor pressure of any liquid component to the test cavity, any vapor pressure value is to be considered less important.

The pressure versus time paths measured according to the methods according to the invention in a preferred embodiment and the devices according to the invention in a preferred embodiment have containers with large leak openings (FIG. 11A), a container with small leak openings. (FIG. 11B) and the non-leakage vessels (FIG. 11C).

These figures will be discussed with reference to FIG. 12 showing the preferred monitoring and control device according to devices 15, 17 of FIG. 2.

According to FIG. 11A, the timing device 201 of FIG. 12 starts vacuum suction of the test cavity 103 by the pumping facility 105 at time t ₁₀ . This is shown by the vacuum suction start signal EVST / t ₁₀ in FIG. 12.

After a fixed amount of time ΔT, e.g., 0.75 seconds, the output signal A ₅ , of the pressure sensor (not shown in FIG. 12) inside the test cavity 103, is a preset source ( The first reference signal preset in 107 is compared with RFVGL. For this purpose, the comparator device 109 is enabled by the timer device 201 at time t ₁₀ + ΔT.

If the pressure actually monitored according to the electrical signal A ₅ of FIG. 12 after the time period DELTA T does not reach the value of RFVGL according to the path I of FIG. 11A, this means that a very large leak opening VGL is present. This is detected in the comparator ₁₀₉ which produces an output signal A ₁₀₉ . According to the properties shown in block 109 of FIG. 12, this comparator device 109, enabled at time t ₁₁ = t ₁₀ + ΔT, is still at a high level, for example, still indicating the presence of VGL. If so, this is the output from the VGL output. If the prevailing pressure around the vessel 103 under test, ie within the test cavity, has reached the reference level RFVGL along path II of FIG. 11A, the VGL output is not generated.

As will be explained later, the generation of the VGL signal preferably stops the vacuum suction cycle, since contamination of the vacuum pump 105 may or may occur because of a very large outlet of the vessel under test. .

Since VGL does not occur as shown in path II of FIG. 11A, vacuum suction continues until time t _13, which is further improved. At time t ₁₃ , the timer device 201 does not operate the pumping facility 105 and disconnects the pumping facility from the chamber 103 with something like a valve 106. Further, the timer device 201 causes the comparator device 111 to operate, which is guided to an additional reference value RFGL generated by the reference signal source 113. If the dominant pressure in the periphery of the test cavity at t ₁₃ has not reached RFGL, the comparator device 111 generates an output signal GL indicating that the container has a large leak port during the test. As will be further described herein again and later, some reactions are taken with respect to further operation of the inspection system.

If signals VGL or GL are initiated by the associated comparators 109, 111, the timer device 201 is usually reset because the inspection has been completed and the quality of the containers inspected simultaneously has been identified. This is shown diagrammatically by the signal RS ₂₀₁ in FIG. 12. If not reset, shortly after t dominant value A ₅ (t ₁₃₎ of the pressure in the surrounding of the container ₁₃ are stored in the keep to storage device 117. The output of the holding or storage device 117 is directed to an input of the car generating device 119, while the second input of the device 119 is an output A ₅ of the pressure sensor for monitoring the ambient pressure of the vessel under test. Leads to. As shown schematically in the device 121 of FIG. 12, after a preset test cycle time T _T starting at t _13, at the output of the device 119, as represented by the switching device 123 in FIG. 12. The pressure difference DP of is evaluated. This pressure difference DP is fed to an additional comparator device 125 which becomes operational after the elapse of the test time T _T. The reference value DPREF is fed to the comparator device 125 by an additional reference value source 127. As will be explained later, the value of DPREF may be adjustable with respect to time and / or the reference value ψ _{R with} which DPREF is compared against it may also be adjustable with respect to time.

If the DP at time t ₁₃ + T _T is greater than the reference value DPREF, a signal FL is generated at the device 125 indicating that there is a fine leak FL in the vessel under test. This is for the situation as shown in FIG. 11B. If the DP does not reach DPREF, the container is considered not leaking since none of the VGL, GL and FL signals are generated. This is for FIG. 11C.

If the VGL signal is generated according to FIG. 12, whether the single chamber or one pump 105 is an inline processing connected in parallel to multiple test chambers 103, the vacuum suction pump 105 is connected to any such test to which it is connected. It is immediately disconnected from the chamber 103. This is because in the case of very large leak openings, the vacuum pump 105 may be contaminated by the leaking contents of the container. For such a case it is of course also possible to provide an excess pumping facility that can be connected to the one or more test chambers to continue the test while reassembling the first pumping facility that may be contaminated.

In a multi-chamber inline inspection system, for example in a rotary round-turn inspection plant with multiple inspection chambers, the generation of signal GL, which means a large leak opening, and possibly the generation of signal FL, which means a fine leak opening. Again, it is not possible for the chamber with the leaking container to additionally be supplied with the container to be inspected, while the other chambers are still in operation, to inspect the newly supplied containers. Is preferred. This avoidance of the test chamber in which the container is found to be leaking severely or weakly leaking is to avoid affecting the subsequent test results in the chamber, as subsequent test results may have contaminated the chamber. The contents of the leaking container may not accurately indicate whether another container has leaked afterwards.

This avoided chamber is rearranged during subsequent inspection cycles in other chambers.

Refurbishment can be done by heating the chamber and flushing it with a liquid and / or gas, in particular a heater gas. Whether the chamber has been properly rearranged can be checked by performing an inspection as if there is a container to be inspected in it. In that regard, if the DP according to FIG. 12 in the empty chamber does not reach, for example, DPREF or does not reach the appropriately set "empty chamber DPREF" value (ECDP-REF), it means a suitable reconditioning state. . Such an ECDP-REV may be provided by measuring DP _e in clean, empty test chambers and storing these measurements DP _e as relevant reference values for inspecting the chambers for proper rearrangement.

11A and 11B, it will be appreciated that setting the reference value RFGL and in particular setting the reference pressure difference value DPREF can be very important and can greatly affect the accuracy of the system. In that regard, the effects of ambient temperature, atmospheric moisture, slight contamination of the pump, etc. can affect the dominant pressure path, so if these critical reference levels and especially DPREF are If set for accuracy, it can lead to wrong results.

In FIG. 13 qualitatively the pressure path measured in the test cavities without the vessels along the paths of FIGS. 11A-11C. At t ₁₃ slightly different pressure values occur statistically. Therefore, before starting the inspection of the containers in the multiple inspection cavity plant, tightly sealed unfilled inspection cavities are inspected according to FIG. 13 to establish an average (RFGL) _m . The value of RFGL as used in the comparator 111 of FIG. 12 or as used in accordance with FIGS. 11A-11C is found in that the offset value? RFGL is added to (RFGL) _m . It should be pointed out that environmental parameters such as temperature, atmospheric humidity, etc., can be considered constant during the calibration cycle, which is done in empty and maintained test cavities resulting in measurement results according to FIG. 13. Nevertheless, during ongoing time, such as during an online inspection, these disturbing parameters may change slowly and change (RFGL) _m . Relevant perspectives determined up to that time each time a related vessel is not severely leaked during multiple or inline inspections, whether in succession in a single inspection cavity or in parallel with multiple or at least two inspection cavities. At t ₁₃ the actual output signal of the pressure sensor enters the averaging device 113 and the m values of the previous pressures of the actual pressures of the vessels that do not leak badly are averaged there. The output averaging result signal corresponds to (RFGL) _m of FIG. 13 but changes over time due to changing environmental parameters, for example. Output average result The offset ΔRFGL is summed according to Fig. 13, and the result of such summation is the dynamically changing reference value RFGL, which is applied to the comparator device 111 of Fig. 12. This dynamically varying reference value RFGL is shown in FIG. 15, starting with an initial setup as found, for example, as described with the aid of measurements in the empty test cavities 103.

As can now be clearly seen from FIG. 15, the average pressure value is now (t ₁₃ ) is also the basis for the DPREF to reference. Therefore, and as shown in FIG. 12, the differential pressure reference value DPREF does not refer to an absolute static value such as ψ _R , See.

A further improvement in accuracy is reached as will now be described, which can be realized separately or in addition to realizing a dynamic RFGL and realizing a dynamic upper limit of DPREF based thereon. Thereby and at the end of the time period T _T according to FIG. 16, whenever the output signal FL indicates that the vessel under test leaks, the actual pressure difference DP is directed to the averaging device 135. Average pressure difference signal averaged over previous m test cycles The output signal of the device 135, which is equal to is offset by an amount of DELTA DP, and its result is used as the DPREF signal applied to the device 127 of FIG.

Referring back to FIG. 15, there is a constant DPREF signal, as discussed previously, at the dynamically changing check value DPREF, as shown schematically in the path (DPREF) _t , subject to the technique of averaging DP results. As a result, the perturbation changes with changing parameters and affects the pressure difference.

Dynamically changing base value It is clear that it is feasible to provide a dynamically changing (DPREF) _t signal as shown in FIG. 15 without providing a Instead of referring to the value, it is feasible to allow (DPREF) _t to refer to the stable constant value ψ _R indicated by the dotted line in FIG. 12.

The evaluations of the output signal A ₅ of said one or more test cavities are preferably performed digitally. In other words, it is done after analog-to-digital conversion of the associated sensor or output signals of the sensors.

In FIG. 17 the actual pressure difference values DP continuously measured in the multiple test cavities of the inline inspection plant are shown in arbitrary units on the time axis. Calculated average pressure difference according to FIG. 16 Is shown and the offset [Delta] DP finally makes (DPREF) _t according to FIG. 15 or FIG. As can be clearly seen, the mean And therefore (DPREF) _t varies over time and with subsequent tests, and pressure differential values higher than that at that moment (DPREF) _{t as} in A It is ignored with respect to the effect on the part because such measurements are due to leaking containers according to FIG. 11B.

In addition, whenever a test of a container inside a particular test cavity results in indicating a leak in a predetermined number of successive tests, for example, three consecutive tests, such a test cavity may also be used for further testing. It is reckoned to be avoided, contaminated or leaking itself. Such inspection cavities may or may not be contaminated with leaking containers during subsequent inspections, which will be revealed as previously described during the refurbishment and during the inspection for proper refurbishment.

In addition, and as already mentioned, for some containers to be inspected, in particular for certain filling products, the test cavities are heated to a predetermined temperature, preferably controlled in each test cavity, for example by a negative feedback temperature control. It is desirable to. Thus, the vapor pressure of the fill product, which depends on the temperature, is within a predetermined pressure range. Such heating is preferably done in a preheating cycle before the actual inspection cycle according to FIGS. 11A-11C.

As mentioned above, the leak opening in the container is identified regardless of whether there is such a leak hole in the area of the container wall exposed to the air trapped in the container or whether there is such a leak hole in the area of the container wall exposed to the fill product. Nevertheless, for some filled goods, such as, for example, having particulate content in the liquid, the associated pressure difference appearing around the vessel under test can cause a difference in time.

Therefore, and as shown diagrammatically in FIG. 18, in some cases it may be desirable to provide one or several inspection cavities 103 for the container 9 to be inspected to be movable. This can be done, for example, by installing the inspection cavities 103 to be rotatable about a pivot axis A and to be driven by the rotation axis 140. There, leads to or from a pressure sensor inside such an inspection cavity, leads to or from a heating installation in such an inspection cavity, etc. can be guided through the drive shaft 140. have. The cavities 1 and 103 are preferably not rotated but are rotationally reciprocated as shown by ± φ in FIG. 18. By this technique, and as shown graphically in FIG. 19, the leak opening L is in contact with air and in contact with liquid, whether in the position according to FIG. 19A or the position according to FIG. 19B The evaporation of the liquid content in the gas will always be considered as long as it occurs.

Whether in a single chamber inspector or in a multiple chamber inspection plant such as inline inspection, the proper operation of the inspection device and the calibration of the evaluation device are furthermore preferably, preferably mounted on the inspection plant, With the help of standard leak installations, recalibration and / or a complete inspection of the plant can be made whenever desired. A facility of such a standard or graduated leakage facility is shown in FIG. 20.

According to FIG. 20 a needle valve 142 is provided in the line to the vacuum pump 105 from an inspection cavity such as 103 according to FIG. 12, the needle valve being adjustable but preferably not modifiable by the user of the plant. Preset for the predetermined leak value. Through the needle valve 142, the line to the vacuum pump 105 is connected to a liquid reservoir 144, which is preferably filled with distilled water. The reservoir 144 can be pressurized adjustable by the pressure line and the valve 146. The needle valve is set to such a value that the distilled water of the reservoir 144 excluding steam does not penetrate into the connection line to the vacuum pump 105 of the chamber 103. Nevertheless, by controlling the pressurization of the water in the reservoir 144 by the lines and valves 146, various amounts of leakage can be achieved without permeation of liquids and contamination of the chamber and / or connecting lines and / or vacuum pumps. This can be simulated. For plants with multiple test cavities such calibration facility with needle valve 142 may be provided centrally and connected in parallel to all chambers 103, which all the chambers have Or it is likewise desirable to have one central pumping facility 105 acting in parallel to the cavities. Alternatively such calibration facility may be provided separately for each of the chambers 103 installed.

By applying the described technique of checking for leaks by lowering the ambient pressure of the vessel under test below the vapor pressure of the liquid component of the contents, there is usually no need to provide additional resistance measurement equipment as described with reference to FIG. 8. Therefore, it was recognized that the electrode installation and the measuring devices can be omitted in the respective inspection chambers, thus simplifying the entire plant and reducing the cost. The present invention is particularly suitable for inspecting vials or blisters for medical instruments by checking every vial or blister in-line with their production. If, and as shown schematically in FIG. 6, a number of containers 9 are mechanically connected together to form a set of such containers, obviously, with regard to leak inspection, such a set is considered one container.

According to the method and apparatus of the present invention for such things as blisters, the entire inspection cycle, ie from t ₁₀ to the end of T _T according to FIG. 11, takes place in less than 2 seconds. This results in a very high throughput in an inline plant, for example with a large number of test cavities, for example 24, placed on a circular lathe.

Claims (65)

A method for leak checking at least one filled and hermetically sealed container, wherein a pressure differential is applied across a portion of the container wall, the contents of the container including at least one liquid component, at least the portion to be leak tested, and the applied The pressure difference is directed towards the vessel, the pressure around the vessel being monitored as a leak indication signal, wherein the pressure difference is determined by lowering the pressure around the vessel to at least a value corresponding to the vapor pressure of the at least one liquid component. Leak test method. 2. The method of claim 1, wherein the surrounding pressure is lowered to a pressure value of at least two digits, preferably at least three digits lower than the vapor pressure. 3. The method of claim 1 or 2, wherein if more than one liquid component is present, the vapor pressure is the higher vapor pressure of the vapor pressures of the two or more components. The method of any one of claims 1 to 3, wherein the inspection is performed at room temperature. The leak test method according to any one of claims 1 to 4, wherein the pressure monitored as the leak indication signal is monitored after reaching the vapor pressure. 6. The method of any one of claims 1 to 5, wherein the monitored pressure is collected at a first time to produce a first pressure measurement signal and at a second time following time to produce a second pressure measurement signal. And the pressure difference generated by the two pressure measurement signals is evaluated as a leak indication signal. 7. The method of claim 6, characterized by generating the first and second measurement signals as electrical signals and storing the first signal to at least the second time. 8. The method of claim 6 or 7, further comprising providing a pressure measuring sensor within said periphery and connecting said sensor to both inputs of said tea generating device at said first time of use and to an output signal of said tea generating device. Generating a zero offset signal dependent from the signal, storing the zero offset signal, and compensating for the zero offset in the signal difference of the two measurement signals by the stored zero offset signal. method of inspection. 9. A leak according to any one of claims 6 to 8, characterized by providing a pressure measuring sensor within said periphery, and comparing the output signal of said sensor with one or more predetermined signal values. method of inspection. 10. A method as claimed in any one of claims 6 to 9, wherein the first measurement signal is stored using an analog-to-digital converter, which is activated for conversion at the first time. 11. The method of claim 10, characterized by reconverting the digital output signal of the analog-to-digital converter to an analog signal. 12. The method of any one of the preceding claims, further comprising the step of simultaneously testing the batches of containers as one container. 13. The method according to any one of claims 1 to 12, wherein the resistance measurement is performed at or near the portion of the wall in the periphery, preferably by direct current resistance measurement, and by the result of the impedance measurement. And activating or deactivating additional drops of the pressure in the surroundings. 14. An inspection cavity as claimed in any preceding claim, providing an inspection cavity having an inspection chamber that snugly fits into the outer shape of the at least one container, thereby providing a surplus space in the portion to which pressure is to be lowered and Holding between said portion and the wall of said test cavity. 14. The method of any one of the preceding claims, wherein providing for the at least one vessel an inspection cavity defining for an inspection chamber that is much larger than the volume of the vessel. 16. The method according to any one of claims 1 to 15, further comprising: providing a test cavity for the container and cleaning at least the test cavity after the container inside the test cavity is detected to leak, wherein the cleaning is performed. Leak testing and / or heating of the cavity into a gas, preferably by nitrogen and / or by heating. 17. The method according to any one of claims 1 to 16, characterized in that the series of said containers are tested in-line in a set of test cavities and if a previously tested container in a test cavity is found to leak, And inactivating the inspection at the inspection cavity for at least one inspection cycle. 18. The method of any one of the preceding claims, further comprising raising the internal pressure of the vessel by applying mechanical force inwardly to at least a portion of the wall of the at least one vessel. 19. The process according to any one of claims 1 to 18, further comprising vacuum suctioning the surroundings to less than 20 mbar, preferably to about 10 ^-2 mbar for at least one vessel having water as the one component. Leak test method characterized in that. The method according to any one of claims 1 to 19, Initiating a drop in said pressure at a predetermined suction power, If the monitored pressure does not reach a predetermined first pressure within a predetermined time period, determining a large leak opening; Deactivating further drop in pressure; Monitoring the change in the monitored pressure for an additional predetermined time and determining that there is a small or no leak opening in accordance with the degree of the change. 21. The method of any one of claims 1 to 20, further comprising the step of lowering the pressure for a predetermined time and at a predetermined suction power. 22. The method according to any one of claims 1 to 21, wherein the maximum limit at which the monitored pressure must be reached after the fall of a predetermined time is set, and if the monitored pressure reaches the maximum limit at the predetermined time. If not, further comprising the step of deactivating the pumping facility to lower the ambient pressure. 23. The method of claim 22 wherein the deactivation comprises disconnecting the pumping facility from the surroundings. 24. The method of claim 23, further comprising connecting said periphery to an additional pumping facility for subsequent leak inspection cycles. 25. The method of any one of claims 1 to 24, further comprising: providing the perimeter inside the test cavity for the at least one container, and if at least one container is leaked if the container leaks in the test cavity is detected. Leak testing method further comprising deactivating the test cavity for subsequent test cycles. 27. The method of claim 25 further comprising the step of refurbishing the test cavity during the at least one cycle. 27. The method of claim 26, further comprising performing the refurbishment by one or more of heating, gas purging, and liquid purging. 27. The method of claim 26, further comprising checking whether the inspection cavity has been properly rearranged by performing the leakage inspection without the container to be inspected in the inspection cavity. 29. The method of any one of claims 1 to 28, wherein the step of comparing the signal derived from the monitored pressure with one or more thresholds to identify a leak condition of the vessel and at the inspection cavity defining for the periphery Inducing said at least one threshold value from said pressure monitored without a vessel. 30. The container of any of claims 1 to 29, further comprising monitoring the pressure at one or more predetermined moments after the lowering has commenced, and receiving a signal derived from the monitored pressure at the predetermined moment. Comparing the threshold with a threshold to identify a leak condition of the sensor, and if the identification reveals a container that is not leaking, allowing additional signals derived from the monitored pressure to be averaged with additional signals for previously inspected containers. And deriving the limit value from the result of the mean. 31. The method of claim 30 wherein the signal derived from the monitored pressure at the predetermined moment is a difference signal for the signal derived from the monitored pressure at a further predetermined moment. 32. The monitoring according to any one of claims 1 to 31, wherein the monitoring is provided by providing at least one inspection cavity for the vessel and conducting the leak inspection in the inspection cavity free of the vessel and connected to a reference leak installation. Leak test method further comprising the step of calibrating the pressure. 33. The method of claim 32, further comprising the step of providing said reference leakage facility by a needle valve to a reservoir containing liquid and adjustablely pressurized. 34. The method of claim 33, wherein the reservoir contains distilled water. 34. The method of claim 33, further comprising adjusting the reference leak and pressure to prevent liquid from leaking therefrom and to allow vapor of the liquid to pass therethrough. 36. A method according to any one of claims 1 to 35, wherein said periphery is provided in a test cavity, said leak test is performed continuously on said different containers with said test cavity, and if a predetermined number of consecutive If the container leaking for the tests is identified therein, further inactivating the test cavity for further testing. 37. The method of any of claims 1 to 36, further comprising heating the ambient to a predetermined temperature during the inspection. 38. Leakage according to any one of the preceding claims, further comprising the step of conducting an inspection operation to identify larger leak openings in the at least one container prior to performing the method for leak inspection. method of inspection. 39. A method according to any one of claims 1 to 38, wherein a series of said vessels are in-line tested within a set of test cavities, thereby converting said monitored pressure in each of said test cavities into an electrical signal and free of containers. Generating at least one reference electrical signal by lowering the pressure in the test cavities. 40. A method according to any one of the preceding claims, wherein one set of test cavities, each defining for one of the perimeters, are provided, and at least one preliminary after the drop in pressure in the respective perimeters begins. Monitoring the pressure in the surroundings at a determined moment; Comparing the signals derived from the monitored pressures at the respective predetermined moments with a common threshold, respectively, to identify leakage conditions of the vessels in the inspection cavities, If the identification results in a container that does not leak, causing the additional signals derived from each of the monitored pressures to be averaged with those additional signals previously generated, and deriving the common threshold from the results of the averages. Leak test method. 41. The method of claim 40 wherein the signals each derived from the monitored pressure at the predetermined instant are differential signals with respect to the signals each derived from the monitored pressure at a further predetermined instant. 37. The method of any one of claims 17, 25 and 36, further comprising the step of reassembling the test cavity deactivated from the test and reactivating the test cavity for testing after reassembly. 43. The method of claim 42, further comprising the step of refurbishing by one or more of heating, gas flushing, liquid flushing. 43. The method of claim 42, further comprising checking whether the inspection cavity has been properly rearranged by performing the leak inspection in the inspection cavity without the at least one container inside. A leak test apparatus for leak testing at least one hermetically sealed and filled container having contents comprising at least one liquid component, At least one hermetically sealed test cavity, At least one vacuum suction pump connected for use in said test cavity, At least one pressure sensor connected for use in said test cavity, The vacuum suction pump is selected to be able to pump the test cavity to at least the vapor pressure of the component at room temperature, The pressure sensor is a vacuum pressure sensor Leak test device. 46. The leak test apparatus according to claim 45, wherein the vacuum suction pump is at least one of a drag vacuum pump, a piston valve vacuum pump, a diffusion pump, and a turbo vacuum pump. 47. A leak test apparatus according to claim 45 or 46, wherein the sensor comprises a pirani sensor. 48. The method of any one of claims 45 to 47, wherein once the pressure inside the test cavity reaches at least the vapor pressure value, operatively connecting the output of the sensor to the output of the device that generates a leak indication signal. Leakage testing device comprising a timing device. 49. A leak according to any one of claims 45 to 48, wherein said vacuum suction pump is selected such that said vacuum suction pump is capable of pumping said test cavity to a pressure at least to one, preferably two or more preferably three positions less than said vapor pressure. Inspection device. 50. A storage device as claimed in any one of claims 45 to 49, wherein the storage device is operatively connected to the output of the sensor, and one input is operatively connected to the output of the storage device and a second input is of the sensor. And a difference generating device operatively connected to the output, wherein the timing device operatively connects the output of the sensor to an input of the storage device at a first time point, and at a second time point of the storage device. A leak check device operatively connecting an output to said one input of said car generating device and an output of said sensor to said other input of said car producing device. 51. The device of claim 50, wherein after the sensor detects that the pressure inside the test cavity has reached the vapor pressure, the timing device activates an operative connection of the output of the sensor to the storage device. Leak test device. 52. The device of claim 50 or 51, wherein the storage device comprises an analog-to-digital converter and the timing device is operatively connected to the conversion control input of the analog-to-digital converter. 53. The apparatus of any one of claims 45-52, wherein the timing device connects the output of the sensor to both inputs of the difference generating device at the first time point and is operatively connected to the output of the difference generating device. Leakage testing device, characterized in that it is activated at the first time point including an additional storage device connected so that the output of the additional storage device is operatively connected to the output of the car generating device at the second time point. 53. The device of claim 52, wherein a digital-to-analog converter is operatively connected to the output of the analog-to-digital converter, such that the output of the digital-to-analog converter is operatively connected to the difference generating device. . The inspection cavity of claim 45, wherein the inspection cavity has a shape that snugly fits into the at least one container and includes support means on an inner wall between the wall of the container and the wall of the inspection cavity. Leak inspection device to maintain the free space once the volume between them. 56. The apparatus of claim 55, wherein one or more pairs of impedance measuring electrodes are connected to an impedance measuring device, preferably a resistance measuring device while inside the cavity, the output of which activates further vacuum suction of the test cavity by the vacuum suction pump. Or inactivate the leak test device. 57. The method of any one of claims 45 to 56, wherein the test cavity is large enough to accommodate two or more of the vessels, preferably a multi-container batch of the vessels. Leak test device. 58. A leak test apparatus according to any one of claims 45 to 57, wherein the test cavity is sufficiently larger than the container and is adapted to flexibly accommodate containers of various shapes and various volumes. 59. The method of any one of claims 45 to 58, wherein the cavity comprises a removable cover, wherein one or more pairs of seals are positioned around the opening opened by the cover and the space between the two seals is pumped. Leakage test device. 60. The set of inspection cavities of any one of claims 45-59 for in-line inspection of a plurality of vessels, wherein the set of inspection cavities to which the relevant number of vessels are supplied for inspection is such that the vessel previously inspected in any inspection cavity has leaked. And further comprising control means for preventing the inspection cavity from being filled in at least one container to be inspected after it has been found. 61. A leak test apparatus according to any of claims 45 to 60, further comprising one or more cleaning gas lines leading into the inspection cavity and connected to a cleaning gas tank, preferably a cleaning gas tank containing nitrogen. 62. A leak test apparatus according to any of claims 45 to 61, comprising a plurality of test cavities installed in a rotary circle shelf for in-line leak testing of the containers. 63. The method of any of claims 45 to 62, An evaluation device having at least one pressure signal input, said evaluation device At least one comparator device with one input operatively connected to said at least one pressure signal input and a second input operatively connected to an adjustable threshold device; An average device tunably operatively connected to said input, The evaluation device generates a leak indication signal, The leak indication signal regulates the operative connection of the input and the average device, The output of the average device adjusts the adjustable limit device, Leak detection device. Use of one of the methods of claims 1-44 or the apparatus of claims 45-63 for leak testing blisters, medicine bottles, medicine containers, food or beverage bottles, tanks. Use of one of the methods of claims 1-44 or the apparatus of claims 45-63 to permanently inspect the tank plant for leakage.