System and method for detecting possible loss of integrity of flexible bag for biopharmaceutical product

Abstract

To provide a system and a method for detecting a possible loss of integrity of a flexible packaging, for example, a flexible bag intended for receiving a biopharmaceutical fluid.SOLUTION: The integrity of a flexible bag is verified by a testing system (1) that detects the existence of a possible hole by using helium. The flexible bag (2) is preliminary placed in a vacuum chamber (CH) of a fluid-tightly isolated enclosure (10). After connecting a port (11) of the bag to a helium feeding pipe (3a), vacuum suction is executed to obtain vacuum outside the bag in the enclosure. Then, a first amount of helium is diffused in the internal volume (10a) through a gas permeable wall, to increase the helium partial pressure outside the flexible bag. Subsequently, in a test phase while the vacuum suction is still performed, the bag is filled with a second amount of helium. Helium detection means (9) of the system (1) detects information representative of the helium partial pressure in the internal volume (10a), and analyzes a helium partial pressure drop to detect helium escaping from the bag.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a system and method for detecting the possible loss of integrity of flexible packaging, for example, a flexible bag intended to receive biopharmaceutical fluids.

[0002] The term "biopharmaceutical fluids" is understood to mean products resulting from biotechnology (culture media, cell cultures, buffers, artificial nutrients, blood products and derivatives of blood products) or products intended for use in the pharmaceutical or, more generally, medical fields. Such products are in the form of liquids, pastes or possibly powders. The invention also applies to other products subject to similar requirements regarding their packaging. Such products are usually of high added value and it is important to ensure the integrity of the packaging in which they are contained, in particular that they are free from contamination. [Background technology]

[0003] For storage and transport purposes, such biopharmaceutical liquids are customarily placed in bags with plastic walls that are flexible, closed and sterile. It is essential that such bags are liquid-tight when receiving the biopharmaceutical fluid before or during its use, or at least have a sufficient level of liquid-tightness to preserve their possible contents from degradation occurring outside the bag, such as contamination. It is therefore necessary to be able to easily detect loss of integrity of the bag before, during or after use.

[0004] Various methods are currently known to verify the integrity of bags suitable for containing biopharmaceutical fluids. The first known methods consist of physical tests to determine whether there are leaks or holes in the wall of the bag. European Patent No. EP2238425 describes a method in which pressure inside an empty sterile bag is increased between two plates, limiting its expansion.

[0005] A porous material is placed between the walls of the bag and each plate, preventing contact between the walls and the expansion limiting plates from masking a leak. After inflating the bag, the change in pressure inside the bag (with the bag sandwiched or restrained between the two plates) is measured. The pressure drop inside the bag is analyzed. If there is a bag leak, in such a restrained state, the measured pressure will drop below a given threshold over time, allowing a loss of integrity to be concluded.

[0006] US2014 / 0165707 discloses another method for testing the integrity of a bag: the bag is placed in a compartment and a structured permeable receiving layer is placed between the bag and the compartment. The bag is then connected to a source of fill fluid to generate a predetermined positive pressure therein.

[0007] The pressure variations in the bag are then analyzed to determine whether the bag is liquid-tight and therefore intact. Similarly, US8910509 or US2014 / 0083170 are known which describe portable devices for verifying the integrity of a bag, where the bag is preferably filled with sterile air before measuring the pressure in the bag to detect loss of integrity.

[0008] There are also other known methods for verifying integrity using an inert tracer gas. For example, in an integrity test using helium as the gas tracer, the entire bag is placed in a liquid-tight enclosure, which is sealed around the bag, and then a vacuum is created within the enclosure. A specific amount of helium (He) is then introduced into the bag. If there is a bag leak, a mass spectrometer detects the presence of helium outside the bag within the enclosure volume.

[0009] These physical test methods are suitable for testing the integrity of flexible containers or bags, provided that they can demonstrate the absence of leakage paths up to a size that would prevent microbiological ingress. The most sensitive method known at the time and suitable for flexible containers is the gas tracer method.

[0010] Current gas tracer measurement equipment (mass spectrometers) can detect low partial pressures representing micro-leaks well below 2 μm. However, there are other limitations to detecting leak sizes below 2 μm. To obtain a sufficient signal-to-noise ratio, with a 2 μm leak size, the residual He level in the vacuum chamber must be kept above 1000 mbar (5.10 -3 The test must be performed below the natural concentration / partial pressure of He in air (1000 psi, ...

[0011] For flexible plastic containers, measurements of compliant products are subject to several noise sources (one of which is the natural He concentration / partial pressure) that increase the signal amplitude, so the leak rate cannot be easily determined (the signal representing the measured rate for a good bag that should pass the test may resemble a kind of signal representing a defective product).

[0012] The noise can be caused by a variety of conditions, depending on the humidity level within the enclosure, the flexibility, and / or the physicochemical state of the bag. Despite the gas barrier film typically present in the flexible bags or similar devices under test, the penetration of helium through the plastic film will produce a leak rate even in a solid product.

[0013] Extremely high levels of sensitivity (10 -8 A method is needed to provide a pressure drop of up to 1000 psi (up to 1000 psi) in a single step, .... This allows the process to be partially or fully automated, with the possibility of being directly integrated into the production line if desired.

[0014] Current physical methods are ineffective in detecting micro-leaks in bags, e.g., pores less than 2 microns in diameter. Also, detection of leaks due to pores less than 2 microns is difficult because the leak rate is often too small to be distinguished from background leak rates and bag-specific noise (even the use of oxygen barrier layers such as EVOH does not prevent helium penetration). However, it is known that some microorganisms can pass through pores smaller than this size, especially sub-micrometer sized pores under certain conditions, e.g., during immersion bacteriological challenge testing. Thus, the use of the above physical testing methods does not guarantee the absence of microbial ingress into the bag under such specific conditions. Summary of the Invention [Problem to be solved by the invention]

[0015] Thus, in the particular field of the present invention, there is a need to efficiently test bags intended to be filled with biopharmaceutical fluids while detecting the smallest possible micrometer and sub-micrometer pores, and to simply test the integrity of such bags prior to use with the same or even higher level of reliability than currently known or used methods. [Means for solving the problem]

[0016] To remedy the situation, an embodiment of the present invention provides a testing system for verifying the integrity of a flexible bag using a gas tracer, the system comprising: - a housing defining a vacuum chamber, the housing having an internal volume that is liquid-tightly isolated from an exterior of the housing in an operative configuration; a first helium supply device with a supply pipe for filling the flexible bag with helium in a filling step via an outlet of the supply pipe when the flexible bag is placed in the vacuum chamber so as to be surrounded by an internal volume; a vacuum suction assembly for performing vacuum suction and extracting gas from an interior volume outside the flexible bag in a suction mode; at least one pressure measuring member for detecting a partial pressure of helium in a detection region of the internal volume, the detection region being in communication with a suction inlet of the vacuum suction assembly; at least one source of pressurized helium adapted and intended to be introduced into the flexible bag.

[0017] The test system also includes: a second helium supply device for adding helium (e.g. from at least one source of pressurized helium) to the internal volume of the vacuum chamber outside the flexible bag, the second helium supply device comprising: -Unlike the supply pipe, in communication with a gas source, which may be at least one pressurized helium source; the second helium supply including a supply member; - a control unit for controlling the first helium supply device and the second helium supply device, the control unit being adapted to trigger the second helium supply device before the first helium supply device; an analysis module that uses information representative of the change over time in the helium partial pressure detected by the pressure measuring element before and after the filling step, said analysis module being configured to detect a helium leak based on said information.

[0018] The information representing the change in helium partial pressure over time is given as the time derivative and / or the leak rate (mbar.Ls -2 or mbar.Ls -1 Such information can be analyzed taking into account similar information recorded on integrated (defect-free) test samples.

[0019] Typically, the analysis module is adapted to use information representative of the change over time in the helium partial pressure detected by the pressure measuring member before and after the filling step to obtain a test result representative of the helium partial pressure drop in the detection area, the analysis module comprising: - using information representative of the helium partial pressure detected by the pressure measuring member after the addition of helium by the second helium supply device during a period including a period after the filling step when the vacuum suction assembly is in the suction mode; - when the vacuum suction assembly is in the suction mode, prior to the filling step, determining a background value determined based on information representative of the helium partial pressure detected by the pressure measuring member, and then subtracting the determined background value from the raw measurement value; and configured to compare the test result to at least one reference result to identify whether the helium-filled flexible bag passed integrity verification.

[0020] Subtraction of the determined background value can be performed after adding a tracer gas to the internal volume. Assuming that helium is the tracer gas, the injection of helium can be a step that depends on the value of the first derivative of the helium partial pressure in the detection area. The injection is usually performed after a calculation routine and only if a condition is met (such a condition may usually reflect an unsuitable situation for direct analysis).

[0021] In fact, for each test, the analysis module calculates the first derivative of the helium partial pressure in the detection area. When the measured helium partial pressure in the detection area reaches the trigger point (meaning that the noise is small enough to trigger the measurement phase), it is checked whether the first derivative of the helium partial pressure is in a predefined range (between a lower and upper limit). If the "slope" (in the leak rate graph) is outside the appropriate range (i.e. not representing measurements that are considered reproducible), a helium injection is performed by a second supply device. This allows a stabilizing effect to detect lower leak rates.

[0022] Conversely, if the first derivative of the partial pressure of helium is within a given range, there is no need for an injection (no need for a stabilizing effect). Subtraction of the determined background value can be performed without such an injection and the test conclusions are obtained in a more conventional manner. The test result may represent the end of the helium partial pressure drop in the detection region and therefore may be determined at the end of a typical duration of partial pressure fluctuation due to bag inflation (e.g., a period of about 2.5 seconds).

[0023] If the test results reflect a sufficient reduction in helium partial pressure, then such reduction in helium partial pressure will be observed in the absence of leaks in the bag being tested. Such an arrangement mitigates the effects of the following limitations on the test system: i) The flexibility of the bag or similar container, which artificially increases the helium velocity (leak rate) when measured during filling with helium (the reduction in the internal volume around the inflated bag causes an increase in pressure (partial pressure of helium) in the chamber). ii) Varying release of tracer gas during the test due to tracer gas desorption from the tested material and the vacuum chamber walls.

[0024] Indeed, injecting helium around the flexible bag before the filling step while the test system is in suction mode ensures that desorption (from the chamber surfaces and the surface of the bag material) is more uniform and adjusts the background value of the helium leak rate remaining in the vacuum chamber (despite the vacuum).

[0025] The second supply device can be considered as part of a regulation system for regulating the amount of helium present in the internal volume that can be desorbed just prior to the filling step. The inventors have found that when specifically adding a fixed amount of helium to the internal volume, a low leak rate (typically 10 -8It is observed that it takes longer for the bag to have a constant flow rate (below the threshold of less than mbar.L / sec), for example about 2 or 4 minutes, and ultimately there is less variation due to movement of the bag walls as they expand during the desorption and / or filling steps, making the measurements accurate and reproducible.

[0026] For flexible bags with volumes comprised between 50 mL and 50 L, it has been advantageously observed that the test system can efficiently detect leaks with a leak size of less than 2 micrometers in the flexible bag. This means that the test system is also efficient in efficiently detecting leaks of micrometer size or about 1 or 2 micrometers for large volume bags.

[0027] More generally, such test systems increase the efficiency of testing pouches having a wide range of volumes, including larger volume pouches, e.g., from 50 L to 650 L (e.g., using a specially sized test system for pouch volumes greater than 50 L). In some cases, the time required to reach the threshold may be reduced if leak detection (for micrometer sized leaks) is sufficient to validate / void the integrity of the bag.

[0028] If a subtraction step is performed to subtract a background value determined in a preparatory phase (before the filling step), the analysis module can typically use information representing the time-dependent change in the helium partial pressure detected by the pressure measuring member before the filling step to determine such a background value (e.g. a leak rate value) to be subtracted from the raw measurement value (for leak rate) obtained immediately after the filling step.

[0029] In some embodiments, the specific injection of helium around the bag prior to the filling step can be performed through a porous material. The porous material can be selected to be similar to the background fall rate typically observed due to helium desorption from the material of the bag being tested. Optionally, there is a tolerance threshold to determine whether the bag passes the integrity test, which is 2.00·10 -8 mbar.Ls -1 It may be lower than that.

[0030] Since the helium partial pressure is selectively injected in a controlled manner around the flexible bag after the first suction stage and before a low threshold of leak rate is reached, the helium background value associated with the helium remaining in the vacuum chamber (despite the vacuum) cannot vary with different profiles as in previous methods. In other words, the test method is suitable to reduce the standard deviation of the leak rate measurement after subtracting the background value from the raw measurement.

[0031] Furthermore, the test system may be operated with a very short test time (e.g., about 3-4 seconds after starting the filling step) to avoid any negative effects due to the penetration of helium through the plastic film of the bag under test. The conditioning effect of helium injection into the internal volume around the bag prevents the drawbacks that (within such a short test time) the leak rate measurement of a conforming flexible container is randomly influenced by the bag flexibility (i) and the tracer gas desorption (ii).

[0032] Finally, at the end of the test, the flexible bag (which may have a single package) is considered compliant to prevent the migration of microorganisms from the outside to the inside of the bag if no detectable increase in the helium leakage rate is observed. More precisely, the increased precision allows to ensure that there are no pores of a size larger than the minimum sub-micrometer size detectable when adjusting the amount of helium present in the internal volume just before the filling step.

[0033] The comparison of the test results with the reference results can be based on test results reflecting the change over time of the helium partial pressure in a time slot comprised between 1 and 10 seconds, preferably between 3 and 10 seconds, from the start of the filling step. In such a time slot, the effects of penetration are sufficiently low or insignificant, thus making the test highly accurate. Needless to say, the steps can be controlled in a time sequence and the addition of a certain amount of helium can be carried out at a given moment, usually before the filling step, with a time interval (between the introduction of the amount of helium in the internal volume and the start of the filling step), adapted to adjust the bump or pressure drop present in the graph of the leak rate in the vacuum chamber. The bump is a short-term increase in the helium partial pressure due to the expansion of the bag.

[0034] Furthermore, in order to reproduce the background fall rate usually observed due to helium desorption from the bag material, a certain amount of helium can be injected (in compatible conditions to observe the same desorption phenomenon as after the filling step) through a porous material, for example a thin silicone tube. It may be interesting to perform a subtraction of the background values ​​with respect to the raw measurements obtained at an appropriate period after the filling step.

[0035] Indeed, even if the desorption rate may vary within the same bag having exactly the same conditions before testing, such desorption rate is proportional to a given physical constant for a given bag. As a result, if one first determines the pressure drop that represents the physical constant (the desorption constant for the bag under test) and has a background value corresponding to the same bag, one can better distinguish between deviation effects in the leak rate drop and leakage effects during the testing phase, prior to the filling step.

[0036] Optionally, the control unit is configured to control: a first valve allowing the circulation of helium in the supply pipe during the filling step; and A second valve allowing circulation of helium within the supply member.

[0037] According to another embodiment, the second helium supply includes a valve, preferably a solenoid valve, on the supply member having a gas permeable wall upstream of the supply member for limiting the rate at which helium is added to the interior volume.

[0038] According to one embodiment, the second helium supply further comprises an additional valve, preferably an electromagnetic valve, downstream of the supply member. Such an additional valve, which may allow communication between the conditioning chamber or a similar compartment and the vacuum chamber, is important to avoid lengthening the cycle when not necessary.

[0039] In various embodiments of the invention, one and / or the other of the following details may also be used, possibly separately or in combination. - a second helium supply device for adding helium to the internal volume is disconnected from the mechanical connector for connecting to the flexible bag (the second helium supply device has no opening for communicating with the internal volume of the chamber, and the first helium supply device includes a connector that separates the supply pipe outlet and forms the free end of the supply member in the disconnected state). The -port is typically a port that connects the flexible bag to a pressurized system that includes a first helium supply using a supply pipe. The gas-permeable wall (contained in the supply member) comprises a microporous and / or mesoporous membrane of silicone rubber or glass.

[0040] The supply member comprises a tube made of silicone and is adapted to supply helium by diffusion through the silicone wall of the tube. the at least one source of pressurized helium is a helium source including a single tank outside the interior volume for containing all helium to be injected into the chamber, the single tank being operably coupled to a first helium supply and a second helium supply. A helium source, preferably pressurized helium, extends adjacent to the bag and / or is embedded as part of the bag (operation of a valve associated with such an embedded helium source may optionally be performed by remote control means). The testing system comprises two plates, preferably parallel, in a spaced relationship and a housing for receiving a flexible bag between the two plates, the plates preferably forming a restraining plate for restraining the expansion of the flexible bag when filled with helium during the filling step. -Two plates are fixed plates.

[0041] In various embodiments according to the invention, one or more of the following may be used, optionally separately or in combination: -The bag has an outer packaging / wall that defines a single internal space of the bag. The outer wall of the bag includes a port suitable to be closed or connected in a liquid-tight and removable manner to a source of gas or fluid. -The bag is provided with a fill and / or discharge tube located outside the outer packaging / wall. The bag may include one or more connectors, filters, and sensors.

[0042] Also optionally provided is a system for verifying the integrity of a bag according to the present invention, comprising: a bag according to the invention, a source of pressurized gas intended to be introduced into the intermediate space of the bag; - a member for measuring the pressure of the gas in the intermediate space to compare the pressure drop in the expanded intermediate space with a predefined pressure drop threshold; and - two fixed expansion limiting plates facing each other at a distance, adapted not to prevent leakage of the wall of a second packaging arranged against them;

[0043] In particular, the expansion limiting plates are each covered with a lining that is porous to gas (helium). The present invention also relates to a test method using a tracer gas to verify the integrity of a flexible bag to detect the presence of a possible hole, the test method comprising: -In the preparation stage: providing a test system including a housing defining a vacuum chamber adapted to be liquid-tightly isolated from an exterior of the housing in an operational configuration of the housing; providing an injection device suitable for supplying a tracer gas into the vacuum chamber, the tracer gas preferably being helium; placing a flexible bag in a vacuum chamber and connecting a port of the bag to a supply pipe in communication with a tracer gas source, the tracer gas being typically helium; performing vacuum suction to obtain a vacuum outside the flexible bag within the interior volume of the vacuum chamber; performing a gas tracer injection by injecting a quantity of tracer gas (typically helium) into the exterior interior volume of the flexible bag by an injection device;

[0044] - during a test phase, while said vacuum suction is still being performed: filling the flexible bag with helium in a filling step; detecting information representative of a partial pressure of helium outside the flexible bag in the interior volume, to enable detection of helium escaping from the flexible bag, by using at least one pressure measuring member; Then, in a next step, the test result, which is indicative of the helium partial pressure drop in the interior volume outside the flexible bag, obtained using the at least one pressure measuring member, is compared with at least one reference result to determine whether the flexible bag has passed the integrity verification. Includes.

[0045] Such methods provide higher sensitivity due to more stable conditions. All steps can be performed in the same measurement cycle (e.g., with substantially constant suction performed by at least one vacuum pump or similar vacuum means). Thus, 1 μm leak detection limits (and sub-micrometer leak detection) can be efficiently utilized, for example, to ensure / verify microbial integrity under immersion BCT (Bacterial Challenge Testing) conditions.

[0046] Unlike previous methods involving the analysis of pressure drop, the detection method is risk-free in larger containers (such as 3D bags, typically with volumes of 10 L, 50 L or more) due to the reduction in the standard deviation of the leak rate measurements after subtracting the background value from the raw measurements.

[0047] Using such methods, one can calculate a leak rate based on a determination of the helium partial pressure in the test chamber (usually using a mass spectrometer) and then compare such calculated leak rate to an acceptance criterion (threshold) to determine whether the tested flexible bag passes or fails the test.

[0048] To ensure sufficient sensitivity of the measurement, background subtraction increases the efficiency and reliability of the test. Additionally, the second supply can be configured to add helium slowly, thus mimicking / replicating the background drop rate typically observed due to helium desorption from the plastic material of the bag under test. Silicone tubing can be placed in the tubing before the solenoid valve to avoid long cycles when not needed.

[0049] According to a particular embodiment, in the testing phase: The comparison of the test result with the reference result is carried out based on the helium partial pressure measured in a time slot comprised between 3 seconds and 10 seconds, preferably in a time slot comprised between 3 seconds and 6 seconds, after starting the filling step. - and / or the comparison of the test result with the reference result is carried out taking into account the pressure drop background value obtained before the filling step after injecting the determined gas tracer into the outer internal volume of the flexible bag, the test result being determined on the basis of raw measurement values ​​obtained in a time slot comprised between 3 seconds and 10 seconds after the start of the filling step.

[0050] The tracer gas is helium and the test method, in preparation, is: performing a vacuum suction inside the flexible bag to empty the interior space of the flexible bag; - measuring the partial pressure of helium in a detection area in the internal volume (outside the bag); - calculating the first derivative of the helium partial pressure in the detection region (using a sensor, mass spectrometer, or similar pressure measuring component); Including, When the helium partial pressure measured in the detection region reaches a trigger point (meaning that such pressure is sufficiently reduced (high vacuum) and the noise is small enough to trigger the measurement step), it is checked whether the first derivative of the helium partial pressure is within a predefined range between a lower limit and an upper limit, and helium injection is performed by an injection device in the chamber only if the first derivative of the helium partial pressure is outside the predefined range.

[0051] According to a particular embodiment, in a preparation step, a certain amount of helium is provided to the interior volume outside the flexible bag after a helium partial pressure is measured in the interior volume below a predetermined threshold. Such threshold is 5.10 -3 Less than mbar (typically 4.10 -5 mbar or less), which means that the threshold value typically corresponds to a helium pressure that is lower than the helium partial pressure in ambient air.

[0052] This means that before the test phase (i.e. before the measurements are used for helium integrity testing), a portion of the helium (including the helium recently injected in the supply step) is evacuated by suction from the chamber of the housing in which the flexible bag is located. Optionally, the reference result is or reflects a predefined pressure drop threshold obtained by calculating the time derivative of the helium leak rate detected by at least one pressure measuring member in the detection area of ​​the internal volume.

[0053] If helium leaks from the bag, the partial pressure drop (sudden drop in pressure) that would normally be present when there is no leak will be reduced or eliminated, which may allow detection. According to a particular embodiment, the filling step is carried out to maintain the flexible bag between two expansion limiting plates, facing each other at a distance so as not to prevent leakage of the walls of the flexible bag placed against them. This may be interesting to control the expansion of the interior space of the bag. A porous layer may be used to form a contact against the outer wall of the bag.

[0054] According to a particular embodiment, the flexible bag constitutes or is part of the device under test intended to receive a biopharmaceutical product and comprises several flexible pipes, each connected to a respective port of the device under test, the device under test being placed in the chamber before performing the vacuum suction.

[0055] Optionally, in the preparation stage, performing vacuum suction means evacuating gas in different suction areas of the housing to obtain a vacuum inside and outside the flexible bag in the housing.

[0056] Specifically, the amount of helium injected when performing gas tracer injection into the interior volume outside the flexible bag is a first amount of helium, and the flexible bag is filled with a second amount of helium in a filling step, the first amount of helium being less than the second amount of helium.

[0057] The invention also relates to a system for verifying the integrity of a bag according to the invention, comprising a gas sensing element. In various embodiments of the invention, one and / or the other of the following may also be used, optionally separately or in combination: -The system: A bag according to the invention, a source of pressurized gas intended for introduction into the intermediate space; a control unit including a gas pressure control and management member; and The system further includes an outer container or housing adapted and intended to receive the entire bag. [Brief description of the drawings]

[0058] [Figure 1] FIG. 1 is a schematic diagram of a test system according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a top view of an exemplary flexible bag in which the device to be tested may be formed when carrying out the testing method according to the present invention. [Diagram 3] FIG. 3 is a timing diagram illustrating the operation of the test system, showing the limitations in effectively identifying leaks when the leak size is equal to or slightly smaller than 2 micrometers. [Figure 4] FIG. 4 is a timing diagram similar to FIG. 3 illustrating operation of a test system according to an embodiment of the invention by opening a valve to inject a fixed amount of helium.

[0059] [Diagram 5] FIG. 5 is a schematic diagram of another embodiment of a system for verifying the integrity of a bag as shown in FIG. 2, which includes a source of pressurized helium intended to be introduced into the interior space of the bag on the one hand and around the bag on the other hand, a valve assembly and members provided to manage and control the helium injected into and around the bag.

[0060] [Figure 6] Figure 6 shows the leak rate versus time waveforms obtained using the same conventional leak rate test cycle. The bags are all compliant (no leaks considering the subsequent test / inspection) and in particular, it shows four situations where deviations in the leak rate measurements prevent an effective distinction between intact bags and those with micrometer or sub-micrometer sized leaks. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0061] A detailed description of some embodiments of the present invention, together with examples, is provided below with reference to the drawings. In the various figures, the same references are used to denote the same or similar elements. 1, a test system 1 for verifying the integrity of a flexible bag 2 is shown, the system comprising an enclosure 10, one or more sources of pressurized helium 4 and a pressure measuring member 9, which is typically suitable for providing a measurement reflecting the partial pressure of helium within a chamber CH bounded by the enclosure 10. Within the chamber CH forms a space that is airtight (and thus isolated from the surrounding air).

[0062] The housing 10 may have opposing faces that delimit a receiving compartment for the flexible bag 2. Optionally, two plates 12, 14, e.g. two rigid plate members, are provided to delimit the compartment in which the bag 2 is located. The bag 2 is typically introduced into the chamber CH, here the compartment, in an uninflated / unfilled state.

[0063] In the bag 2 introduced into the chamber CH, only a small amount of air may be initially present due to pressure balance, which is advantageous to limit the amount of gas that is expelled. At least one port, here only one port 11 of the bag 2, may provide communication between the interior space SP of the bag 2 and the source of pressurized helium 4.

[0064] When the housing 10 is tightly closed, the outer wall W of the bag 2 can be considered as a partition wall made of a plastic material (usually a plastic without mineral or metal layers) between the internal space SP inside the bag 2 and the internal volume 10a around the bag 2, which is liquid-tightly isolated from the outside of the housing 10.

[0065] The enclosure 10 has at least two feed parts to allow the tracer gas to be introduced respectively into the internal space SP and into the chamber CH of the internal volume 10a outside the bag 2. The expression "outside the flexible bag 2" means that the gas tracer is injected into the area around the outermost wall of the flexible bag: typically, the outer wall W of the bag 2 is the wall that expands directly when filling the bag with helium, this outer wall W directly separating the internal space SP from the internal volume 10a.

[0066] For example, as shown particularly in Figures 1 and 5, the test system 1 may include a first helium supply 3 having a supply pipe 3a or similar inlet line 27 for connecting a source of pressurized helium 4 to a given port 11 of the flexible bag 2.

[0067] In the embodiment of FIG. 1, at least one valve V1 is included in the first helium supply 3, such valve V1 being arranged between a tank of the source of pressurized helium 4 and an outlet 3b for connection to a port 11 of the bag 2. The source of pressurized helium 4 includes or is itself a helium supply comprising a single tank (outside the chamber CH) for containing all the helium to be injected into the chamber CH. The single tank is operatively coupled to the first helium supply 3 and preferably also to a supply member 5 (e.g. a pipe or similar duct) of the second helium supply 6. In variants, several tanks or separate helium sources can be used.

[0068] The test system 1 comprises a pressure measurement member 9, a housing 10, a control unit 13, and a leak detector assembly including a control and management assembly 28 coupled to the control unit 13, and valves V1, V2, V3, V5 actuated during a measurement cycle by the control and management assembly 28 and / or the control unit 13. The control unit 13 may comprise an analysis module 15 that uses information representative of the helium partial pressure detected by the pressure measurement member 9 during a measurement cycle as shown in FIG.

[0069] A mass spectrometer is typically provided to form the pressure measuring member 9, such mass spectrometer having or communicating with a detection area 10d, capable of measuring and analyzing the pressure drop PD (due to the sudden change in the helium partial pressure in the chamber CH around the just expanded bag 2). The pressure drop PD is systematically created after starting to fill the bag 2 with helium (with an increase in the concentration in the internal volume 10a), since a pressure difference is obtained between the internal space SP of the bag 2 and the internal volume 10a around the bag 2.

[0070] The mass spectrometer is suitable for tracer gas detection (helium detection), especially when a vacuum is created in the enclosure 10 prior to the step of testing the bag 2 in the system 1 . In the embodiment of Figures 1 and 5, the test system 1 is used to detect the integrity of the outer wall W of the bag 2, such wall W extending entirely within the chamber, typically between two plates 12, 14 present inside the chamber CH.

[0071] The housing 10 of the test system 1 is here an outer container in which the bag 1 according to the invention can be placed. The outer container is larger than the bag 2 (or symmetrically the bag 2 is smaller than such an outer container), so that the bag 2 in the inflated state remains in the chamber CH. Optionally, the housing 10 may include a lining that is porous to the gas in the chamber 10, such lining being at least the contact part that is in contact with the bag 2 when it is in the inflated state after the filling step in which the bag 2 is filled with helium (the inert tracer gas). The lining on which the bag 2 is placed does not block the leakage of the outer wall W when the bag 2 to be tested is placed inside the chamber CH.

[0072] The outer container forming the housing 10 may in particular consist of a box or a rigid or semi-rigid fluid-tight shell. More specifically, in one configuration, the housing has the shape of a parallelepiped. The housing 10 may include an opening for introducing the bag 1, which can be selectively opened and closed. To this end, the outer container of the housing 10 may for example include a removable cover or door provided with members for gripping and handling. Preferably, gripping members are provided for quickly locking the cover in a closed position and for capping the opening.

[0073] Referring to FIG. 1, the test system 1 includes a source 4 of pressurized gas (here, in this non-limiting embodiment, pressurized helium) that can be in fluid communication with, or can be in fluid communication with, an outlet of a port 11 of the bag 1, and a line including a supply pipe 3a for injecting the pressurized helium. The first helium supply 3 is connected to the housing 10 at a location different / remote from the port 30 or the pipe connecting the pressure measuring member 9 to the chamber CH.

[0074] A quantity of helium is intended to be inserted into the interior space SP of the bag 2 via the port 11 and a suitable connecting element of the first helium supply device 3. It is understood that helium (or an equivalent inert gas) is a gas that is neutral and non-toxic with respect to the biopharmaceutical fluids that may form the contents of the bag 2, so as not to contaminate the biopharmaceutical fluids. Although FIG. 1 shows the outer wall W under a single wall form of the bag, the bag 2 may in a variant be provided with one or more external components which partially cover the outer wall W and are in a spaced relationship relative to the outer wall W.

[0075] As shown in Figure 2, the flexible bag 2 in the folded state has two opposing flat faces, and the ports 11 and 12a-12 are provided in one of these main faces. The other two faces are folded. The bag parts forming these other two faces are sheets of plastic material, having the shape of a flat bellows (forming two opposing gussets), inserted between two initially flat sheets forming the opposing faces.

[0076] The flat state of the flexible bag 2 obtained immediately after production is made possible by the overlapping of the welded seams 61, 61' and 62, 62'. The free ends 2e and 2f can be straight edges of the bag 2. Thanks to the typical hexagonal shape of the opposite faces, the bag 2 can easily reach a parallelepiped shape by expansion of the gussets and folding along the parallel fold lines FL1, FL2 (L1 is the distance separating the fold lines FL1, FL2 of the same plastic sheet of the bag 2).

[0077] This is a non-limiting example of a 3D flexible pouch or bag 2. The parallel fold lines FL1, FL2 obtained in the inflated / filled state of the bag 2 are predefined fold lines formed on opposite main faces of the bag 2 (unlike a 2D container).

[0078] Such a bag 2 comprises a bottom wall, a top wall and flexible side walls that can be in two extreme states - folded flat or unfolded and deployed - and can be reshaped to change from one of these states to the other or to any intermediate state. When the flexible bag 2 is filled with biopharmaceutical fluid or filled with gas during testing, it expands more or less. It may form a parallelepiped container. Its bottom wall can rest on the inner surface of the base of the housing 10 or on the inner surface of the restraining plates 12, 14, while its side walls are deployed towards the inner surface of the side walls of the housing.

[0079] The flexible bag 2 is shown here as having a hexagonal shape in an unfilled state. Each sheet forming the bag 2 may have a length L1 that is longer than the long side L2 of the hexagonal flexible bag 2 in the uninflated / unfilled state (the shape clearly visible in FIG. 2). It is understood that the length L1 of the flexible bag 2 in its initial state before filling, when measured from the lower end 2a to the upper end 2b, is greater than the height of the flexible bag or pouch 2 in its deployed and filled state (e.g., this height is substantially equal to the length L2).

[0080] The flexible pouch or bag 2 here has one or more inlet or filling or supply openings, especially in the form of ports 12a-12b (which may form upper ports), especially in the top wall, and one or more outlet or discharge or ejection openings, especially in the form of port 11, especially in the bottom wall. The outer wall W of the bag 2 may thus be provided with at least two orifices, in other words two passages, at least one for filling with a biopharmaceutical fluid and at least one for ejecting the biopharmaceutical fluid.

[0081] Preferably, any lines 7, 9a, 9b, 2b connected to the bag 2, here on the same side of the bag, are referred to as flexible supply lines. Furthermore, each of the flexible lines 7 and 9a-9b is preferably provided with a clamping member, such as clamps C1, C2, C3.

[0082] The inlet openings are adapted to close when required and / or clamp members C1-C2 are used to block access to the interior of the flexible pouch 2. Similarly, one or more outlet openings are adapted to open when required and / or clamp member C3 is used to allow passage of the flexible line 7. The fill and discharge orifices of the wall W are associated by a fluid-tight connection with the fill tubes, respectively. For example, the fill orifices of ports 12a-12b are associated with flexible line 9a and flexible line 9b (typically clamps C1 and C2 are shifted away from ports 12a-12b).

[0083] Although the illustrated embodiment shows the use of port 11 for filling with helium, any one of the filling orifice and the outlet opening can be used to fill the interior space SP of the flexible bag 2 with helium, provided that the other flexible line is connected to a source of pressurized helium 4 by a corresponding flexible line, with the other flexible line closed. In FIG. 5, the port 11 through which helium is injected into the interior space of the flexible bag 2 can be the outlet orifice. The other line can be attached using a fixing device 39, while a clamp (here clamps C1, C2) prevents the helium present in the bag 2 from escaping to the chamber CH, in the interior volume 10a around the bag 2.

[0084] 5, it can be seen that clamps C1, C2, C3 can be used to seal the flexible bag 2 when placed in the housing 10. In a variant, the flexible lines 7, 9a, 9b of the bag 2 can each be connected to a vacuum circuit, for example to the same vacuum circuit.

[0085] In some variants, the bag 2 comprises a packaging that may be 2D, with two wall members directly connected to each other. The bag 2 may also have a 3D type, in other words a three-dimensional packaging. The wall W then typically comprises two parts forming the main faces, such two parts being fixed and hermetically connected to two side gussets by four longitudinal liquid-tight welded seams 61, 61' and 62, 62' (and two transverse welded seams).

[0086] As shown in FIG. 3-4, it can be seen that suction must be performed to reduce the pressure in the chamber CH. If the residual pressure is low enough, the monitoring phase (test phase) of the measurement cycle can be performed. The test phase now starts at t0. At the start of the measurement cycle, the test system 1 can be similar to known systems in that it must reach a low pressure threshold after a waiting period T1. The valve V1 is actuated at t0 in order to obtain an inflated bag 2 adapted for testing.

[0087] The control and management assembly 28 may for example include a pressure controller for the pressurized expansion gas in the supply pipe 3, commanding the injection of gas (helium) on demand (here at t0) and controlling the injection at the desired pressure. Such an assembly 28 may comprise a pressure gauge, an adjustable valve and / or control lines between them. A control line 28a may link the control and management assembly 28 to the control unit 13 in order to regulate the steps in the measurement cycle. The assembly 28 may form part of the control unit 13.

[0088] According to a preferred embodiment, as shown in Fig. 4, the valve V2 for the operation of the second helium supply device 6 allows the circulation of helium towards the internal volume 10a and can be temporarily opened before opening the valve V1 to fill the bag 2. Unlike the conventional preparation stage (as shown in Fig. 3) in which no helium is added around the bag 2, a specific injection 18 is carried out during the period when the suction is carried out, here using the vacuum pump P1, while the bag 2 is not filled with helium. Such injection 18 increases the partial pressure of helium in the internal volume 10a.

[0089] With reference to Figures 3 and 6, when comparing the leak rate curves of some of the conforming products tested, it is clear that after t0, the leak rate measured by the pressure measuring member 9 may deviate (not form a pressure drop PD with the expected significant leak rate), so that curve 51 for a completely intact bag 2 may be similar to curve 52, which reflects a situation in which the bag 2 has a hole of about 1 or 2 micrometers in size, causing leakage. Using a particular injection 18 as shown in FIG. 4, such deviations are greatly minimized and / or testing of a compliant product is easier to conclude.

[0090] Since the injection 18 provides an overview of the profile of the background values ​​(as it causes the reference drop profile), it is easy to extract the background values ​​relevant for the improvement of the test phase carried out after the start of the filling step. The end of the drop in the preparation phase (reference drop profile over time) may reflect background values ​​that should be taken into account. As a result, the problematic case reflected by the curve 51 in FIG. 3 can be optionally solved by subtracting the background values ​​from the raw measurements obtained based on the drop caused by the injection 18 (for example taking into account the level of the leak rate at the end of the reference drop profile).

[0091] 1, it is understood that a certain injection 18 is possible before the gas, here helium, flows through the supply pipe 3a of the first supply device 3. A vacuum pump P1 is involved to evacuate the gas from the chamber CH. The pump P1 acts as or is part of a vacuum suction assembly to perform a vacuum suction and to extract gas from the interior volume 10a outside the flexible bag 2 in suction mode.

[0092] A vacuum pump P2 may be associated with the first supply device 3. The vacuum pump P2 communicates with the supply pipe 3a, for example, via a lateral passage downstream with respect to the position of the valve V1. This vacuum pump P2 is not used in the test phase of the measurement cycle (valve V5 is just closed at t0, and immediately after such closing, valve V1 is opened). The vacuum pump P2 is important to evacuate air from the flexible bag 2 to have a reproducible test gas amount or concentration (He) in the bag 2, otherwise the helium of the source 4 would mix with the remaining air in the bag 2.

[0093] In a preferred option, as shown in Figure 4, pump P2 can be operated immediately in a warm-up phase after starting suction by the main vacuum pump P1 to prevent over-inflation of bag 2. Suction by pump P2 is stopped well before t0 by closing the associated valve V5. Vacuum pump P2 can optionally be used for suction before and possibly after the measurement cycle.

[0094] The pressure measuring member 9 comprises one or more mass spectrometers, typically a mass spectrometer suitable for detecting the helium concentration (partial pressure) in a detection region 10d of the internal volume 10a, which is here in direct communication with a suction inlet of a vacuum suction assembly, which in the embodiment shown in Fig. 1 is for example the inlet of a vacuum pump P1.

[0095] At least one vacuum pump P3 can be associated with the mass spectrometer. Another pump (secondary pump, not shown) can be embedded in the mass spectrometer to form the member 9. The valve V3 can be a conventional valve for such a mass spectrometer. It typically comprises a turbo pump assembly or similar pumping means. The detection assembly forming or including the pressure measuring member 9 can be selected from among several commercially available products and is optionally improved to increase the accuracy of the measurement.

[0096] In a variant, the main vacuum pump P1 can be placed downstream of the valve V3, in a line directly communicating with the duct 30a. The principle of the leak detector of such a detection assembly can be based on a sector field mass spectrometer. The analyzed entry gas (helium in this case) is ionized in the vacuum. The helium ions are accelerated using an added voltage and further separated in a magnetic field. The ion current is converted into an electric current, for example, using a special detector (known per se). This current is accelerated and displayed on a screen using a leak detection unit. The measured current is directly proportional to the helium partial pressure and therefore equal to the measured leak.

[0097] An embodiment of the second supply device 6, optionally the second helium supply device, will now be described in relation to FIGS. The second helium supply 6 for adding helium to the internal volume 10a includes a supply member 5, here separate from the supply pipe 3a, from a source of pressurized helium 4, a tube 32 or a similar part for diffusion of helium through a wall having an outer surface within the chamber CH of the internal volume 10a, or for delimiting all or part of an area in direct communication with the internal volume 10a.

[0098] The tube 32 is typically made of silicone adapted to supply helium by diffusion through a silicone or porous type glass wall of the tube 32. A surface, preferably an inner surface, of the tube 32 defines an area in communication with at least one source of pressurized helium 4 via a pipe of the supply member 5. Valve V2 may be an electromagnetic valve controlled by the control unit 13 via a control line 28a. Using a routine in the control unit 13, valve V2 may be selectively opened to cause helium injection 18 and increase the helium partial pressure in the interior volume 10a around the bag 2.

[0099] 1 embodiment, the second helium supply 6 includes at least one valve V2, preferably a solenoid valve, upstream of the diffusion portion or tube 32 of the supply member 5 ("upstream" should be considered in relation to the flow of gas tracer circulating from the gas tracer source towards the interface where the tracer gas reaches the interior volume 10a around the bag 2). It will be understood that the diffusion portion of the supply member 5 typically has a gas permeable wall to limit the rate at which helium is added to the interior volume 10a.

[0100] In the variant of FIG. 5, the second helium supply device 6 comprises at least one valve V2′, preferably an electromagnetic valve, upstream of the tube, tube 32′ or similar diffusion section of the supply member 5. The second helium supply device 6 also comprises an additional valve V2″, preferably an electromagnetic valve, downstream of the supply member 5. The valve V2″ can extend adjacent to or into the chamber CH. In the tube 32′, the supply member 5 has a gas-permeable wall. Optionally, as in the embodiment of FIG. 1, the permeable wall is adapted to limit the helium rate added to the conditioning chamber CR before being injected into the internal volume 10a (by means of a helium porous material).

[0101] The additional valve V2″, which may allow communication between the conditioning chamber CR or a similar compartment and the vacuum chamber CH, is important to avoid long cycles when not needed. The silicone or glass tube forming the gas permeable wall of the supply member 5, while extending into the conditioning chamber / compartment CR, is placed in the tube in front of the additional valve V2″, so that with the additional valve V2″ closed, no helium is supplied to the vacuum chamber CH.

[0102] In Fig. 5, the control and management assembly 28 may be suitable for controlling the helium circulation in the line 27 of the first helium supply 3 and in the second helium supply 6. In this particular embodiment, the control unit 13 is linked to the control and management assembly 28, so that coordination with the measurements is possible. Needless to say, many other options are suitable for forming and controlling the first helium supply 3 and the second helium supply 6.

[0103] The second helium supply device 6 may be provided with a gas-permeable wall comprising a microporous and / or mesoporous membrane of silicone rubber (or optionally a porous glass member) suitable for diffusing helium towards the interior volume 10a.

[0104] The second helium supply device 6 can be activated by a command from the control unit 13 depending on the result of a calculation performed at an earlier stage when a low vacuum is reached. Typically, the first derivative of the helium partial pressure in the detection area 10d is analyzed. If such a slope is too high or too low, the measurement is not considered reproducible. Now, the injection of helium by using the second helium supply device 6 is performed if the analyzed / determined slope does not reflect the appropriate situation for a reproducible measurement. Such an analysis is performed when the helium partial pressure is as low as 4E-5 mbar (see for example the slope on the left side in Figures 3 and 4).

[0105] When the helium partial pressure measured in the detection area 10d reaches the trigger point (meaning that the noise is small enough to trigger the measurement phase), the first derivative of the helium partial pressure is checked if it is within a predefined range between a lower and an upper limit. Only if the slope observed in the leak rate graph (e.g. in Figures 3-4) is outside the appropriate range, a specific injection 18 (helium injection) is performed by the second helium supply device 6. A calculation routine to detect the need for an injection 18 is performed with each test, which is interesting for some tests, as it gives accurate results quickly, without an injection 18 and without an additional waiting period for the helium partial pressure to drop.

[0106] In the next section, we will discuss some preliminary options, which should preferably be used only if the initial slope is determined to be outside the appropriate range (the situation in Figure 4).

[0107] With reference to Fig. 1, the control unit 13 is configured to trigger the second helium supply 6 before the first helium supply 3, so that during the measurement cycle of a given bag 2 to be tested, valve V1 is actuated after valve V2. The control unit 13 also triggers pumps, for example vacuum pumps P1 and P2, possibly in a conventional manner. When pump P1 is actuated to suck the gas present in chamber CH (at step a / ), a waiting period T1' is usually necessary before starting the filling step to inflate bag 2. Indeed, it is usually necessary to wait for a stabilization period to finish before continuing with the test itself.

[0108] During this waiting period T1', as shown in Figure 4, valve V2 is opened when the helium partial pressure is low enough, so that a helium injection 18 is performed around bag 2. This is performed well before the filling step (i.e. well before t0) in order to generate the reference drop.

[0109] Then, in a next step, the pressure drop in the intermediate space or inner volume 10a is compared with a predefined pressure drop threshold by a pressure measuring member 9 coupled to a control unit 13. This threshold is for example the value of the pressure drop for the bag 2 to have undergone an integrity verification and be considered intact.

[0110] However, if a pressure drop PD is detected (at the end of the normal period) greater than the threshold value, then the outer wall W is deemed to have failed the integrity verification (bag 2 fails the test).

[0111] A measurement is optionally taken in preparation and is used to determine a background value of the reference drop due to injection 18 . Such an option could be implemented in the case of series of bags where pressure deviations pose problems for adequate detection of leaks and / or in situations where it is necessary to systematically find sub-micrometer sized leaks that form a passage for specific bacteria.

[0112] A background value can be determined at the end of the reference drop (end of the peak) if the drop in helium partial pressure is low enough. Such a background value is interesting because it reflects the physical conditions of the chamber CH around the bag 2 and the way in which helium escapes under such conditions. In fact, such a situation shows the profile of the helium leak rate upon an instantaneous increase in the helium partial pressure in the internal volume 10a.

[0113] The test phase can be initiated when the level of helium partial pressure falls below a threshold value, optionally at the same or a similar threshold value, e.g., 4.10 -5 mbar or less may be used by the control unit 13 to trigger the second helium supply device 6 and the first secondary helium supply device 3 only after a leak rate below a predetermined threshold such threshold has been reached.

[0114] Measurements during the test phase reflect the end of the profile of the pressure drop PD. The analysis module 15 uses such measurements (helium partial pressure detected by the pressure measuring member 9) to generate information representative of the change in the detected helium partial pressure over time. The analysis module 15 includes a comparison routine for detecting a helium leak based on such information. Typically, a reference result corresponding to a predefined threshold (a predefined pressure drop threshold) is also used by the comparison routine.

[0115] In some embodiments, the reference result is a predefined pressure drop threshold value obtained by calculating the time derivative of the helium leak rate detected by the pressure measuring member of the detection area 10d. In a variant, the reference result can be determined taking into account the duration of the pressure drop PD and compared with a test result obtained at the same or similar time reflecting the peak / end of the pressure drop.

[0116] More generally, it can be seen that the analysis module 15 can be configured as follows: - when the suction mode is active, using information representative of the helium partial pressure detected by the pressure measuring member 9 after the addition of helium by the second helium supply device 6 for a period including the period following the filling step; and -Comparing the test result to at least one reference result to determine whether the helium-filled flexible bag 2 has passed integrity verification.

[0117] The analysis module 15 may include or be part of a control unit 13, configured for example as a computer unit, including a central processing unit (CPU), a random access memory (RAM), a read only memory (ROM), a flash memory for storing backup data etc., an input interface, and an output interface. Typically, the control unit 13 is an electronic control unit (ECU) that electrically controls the valves V1, V2, V3, V5, for example by including a control and management member 28. The control and management member 28 may be equipped with control lines 28a that allow actuation and / or transmission of commands to the valves.

[0118] The ROM of the control unit 13 stores a program for operating the computer unit as the control unit 13. When the CPU executes the program stored in the ROM by using the RAM as a working area, the computer unit functions as the control unit 13 in this embodiment. A mass spectrometer or similar pressure measuring member 9 for detecting gas within the housing 10 is connected to an input interface of the control unit 13 to provide data to the analysis module 15. Various control objects including valves are connected to an output interface of the control unit 13.

[0119] With reference to FIG. 1, the test system 1 can be a complete system with one or more sources 4 of pressurized tracer gas (here helium or SF6), an enclosure 10, and the following modules: a helium mass spectrometer leak detector, comprising a mass spectrometer 9 adapted to function as a pressure measuring member, and optionally an inlet interface 19 for communication between the chamber CH and a port 30 or a pipe for circulating gas towards the pressure measuring member 9, a vacuum system coupled to the housing 10 to maintain a sufficiently low pressure within the mass spectrometer;

[0120] a vacuum pump, including a pump P2 for evacuating the tested flexible bag 2 (usually step b / shown in Figures 3 and 4), another pump P3 for circulating helium towards the mass spectrometer forming the pressure measuring member 9 (if the mass spectrometer is located outside the chamber CH, as in the embodiment shown in Figure 1), and possibly a main pump P1 used to evacuate the internal volume 10a around the bag 2, Valves V1, V2, V3, V5, which control the individual steps of the measurement cycle (preparation and test phases are part of such a measurement cycle), from evacuation to testing to ventilation,

[0121] An electronic measuring and control system adapted to act as a control unit 13; Power supplies for individual components - valves, circuits, etc. · Fixtures and positioning members (which may include a supply pipe 3, a fixing device 39 and two plates 12, 14) that in particular connect the test product, here a flexible bag 2, into the chamber CH of the housing 10.

[0122] Such a testing system 1 detects leaks in the outer wall W of the bag 2, since here it is a complete system suitable for detecting leaks, by simply continuously measuring the helium partial pressure and analysing, by the analysis module 15 of the control unit 13, the changes over time in the information representative of such helium partial pressure.

[0123] The test method uses a so-called tracer gas - helium - which is used to fill a bag 2 placed in a chamber CH, the internal volume 10a surrounding / outside the bag 2 being connected to a detection assembly equipped with a pressure measuring member 9.

[0124] If helium quickly leaks out of the test bag 2 into the detection area 10d, where the helium partial pressure is measured (and possibly displayed on the screen), no significant pressure drop PD can be identified by the analysis module 15, which means that the detected helium is helium coming from the internal space SP through the holes in the bag 2. Indeed, the permeability through the bag 2 (which typically has a plastic wall W with a thickness of more than 150 or 200 micrometers) allows the helium to escape only after a minimum period that can be better than 4 seconds.

[0125] With reference to Figures 3-4 and 6, it can be seen that after time t0, which reflects the moment of filling the bag 2 with helium (step c / , when valve V1 opens to allow such filling), there is a pressure drop PD, although a minimum period has not yet elapsed. The duration of the pressure drop PD is usually shorter than the minimum period and can be considered to be substantially constant. In fact, in all experiments the start and end of the pressure drop PD are substantially the same. The duration of the pressure drop PD is here around 2.5 or 2.6 seconds, and not longer than 3 seconds, depending on the arrangement of the housing 10 and the type of detection means used in the test system 1.

[0126] During the first few seconds of the test period, after the helium is injected into the bag 2, the flexible bag 2 expands and accordingly compresses the remaining air in the vacuum chamber CH outside the bag 2 (ie, the internal volume 10a decreases).

[0127] As a result, the partial residual helium pressure in the chamber CH increases briefly before decreasing again due to continued evacuation. This is read by the mass spectrometer as an increase and then a decrease in the leak rate, which is usually called the pressure loss PD; meanwhile, the bag 2 is completely liquid-tight. In FIG. 6, it can be seen that all bags 2 under test are completely liquid-tight, but there is no injection of helium into the internal volume 10a. This creates an artifact (bump) that reduces the separation force by a factor of 1000 for leak detection. The leak rate curve 38 is an exemplary curve (worst case for a bag 2 to be identified as compliant with the test) that reflects a high deviation and causes a large loss of separation force.

[0128] In some tests, it was surprisingly found that when injecting helium by the second helium supply device 6, if suction is performed efficiently after such a particular injection, the curves 38 do not actually collide (or collide less), which means that the period during which the mass spectrometer measures the partial pressure of helium remaining in the vacuum chamber CH before helium is filled into the bag 2 is longer compared to the situation where no helium is specifically added to the internal volume 10a.

[0129] As a result, if there is only a slow increase in the leak rate after the pressure drop period has elapsed, such as curve 50 of FIG. 6 with a slow increase in the leak rate after the pressure drop PD, or curve 50' of FIG. 6 with a relatively rapid increase in the leak rate after the pressure drop PD, the analysis module 15 can use a comparison with a pre-set reference result that reflects a no-leak condition, for example a reference result as in the case of curve 50'. Indeed, if the leak rate is measured to be low or below a suitable threshold, for example 10 seconds after t0 (or within a time slot before or after that moment), the analysis module 15 can use a comparison with a pre-set reference result that reflects a no-leak condition, for example a reference result as in the case of curve 50'. -7 mbar.L / sec, it can be effectively concluded that the flexible bag 2 filled with helium has passed the integrity verification.

[0130] In Figure 3-4, step d / corresponds to the period starting from t0 or immediately thereafter, during which monitoring is performed based on measurements (measurements made at least since t0) to analyze the pressure loss. The horizontal scale may be exaggerated in such step d / to better illustrate the pressure drop PD. Step e / shows that the helium partial pressure usually increases after some time after the end of the pressure drop PD in normal situations (see especially curve 50) when the bag 2 is leak-free.

[0131] Of course, the method of calculating the final leak rate value may be different. For example, the analysis module 15 may first determine the turn-up (down) points of the curves 50, 50' as the pressure drop PD elapses, and then estimate whether the level of the leak rate at such turn-up point is sufficiently low (below the acceptable criteria / threshold). If no such turn-up point exists or is found at a value higher than the acceptable threshold, it is concluded that the tested bag 2 has failed the test.

[0132] Advantageously, the tolerance threshold is optionally 2.00·10 -8 mbar.Ls -1 It may be lower. The above method for verifying the integrity of the bag 2 includes a preparatory phase that may be longer than the test phase, especially due to the time required to have a low helium partial pressure before and after the injection 18.

[0133] In a preparation stage, a bag 2 as described and a system 1 as described are provided, as shown in Fig. 5. The bag 2 is empty (without biopharmaceutical fluid) and may initially be flat. The housing 10 is equipped with a single injection line 27 or similar connection that is part of the first helium supply 3, so that at time t0 it is possible to deliver a pressurized gas, here helium, to inflate the flexible bag 2. Before t0, the second helium supply 6 has already been used to perform an injection 18 and the bag 2 is already in the housing 10 (before the measurement cycle is started before the injection 18).

[0134] In some embodiments, the test system 1 is a two-stage aspiration system, i.e.: a first stage in which a first (low) threshold value of the helium leakage rate measured around the bag 2 under test is reached (this first stage allows a first removal of the adsorbed helium); and A second phase after the injection of a new helium dose 18, in which the remaining adsorbed helium and the new helium are removed because a second (lower) threshold is reached (or a second identical threshold is reached). Any suitable helium injection means may be included to implement

[0135] By means of such a two-stage aspiration, the method advantageously reduces the deviation effects of background noise (background noise that may mask leaks to be detected), in particular the background during the pressure drop following the filling step performed at the beginning of the test phase.

[0136] While the detailed embodiments above show the use of a source of pressurized helium 4 that typically contains helium of normal purity suitable for medical use, the amount of helium injected around the flexible bag 2 may optionally be supplemented using a different type of source, possibly using a gas mixture or helium that is not at the same level of purity. Helium is preferably used for a number of reasons: Non-toxic -Inert and non-condensing -Normally not present in the atmosphere, only in trace amounts, -Due to its small atomic weight, it flows easily even through very small leaks -Non-flammable.

[0137] This test method is suitable for detecting leaks of micrometer and sub-micrometer size, even in large-volume bags 2. The housing 10 may be suitable for receiving bags having a volume of at least 2 L, possibly approaching 500 or 650 L. In some embodiments, the bag 2 has a volume comprised between 20 and 50 L. In such cases, a single outer wall W may be provided to delimit an interior space SP that can be filled with a biopharmaceutical fluid.

[0138] Needless to say, the present invention is not limited to the above-described embodiments, which are provided only as examples, and which encompass various modifications, alternative forms and other variations that may occur to those skilled in the art within the context of the present invention, in particular any combination of the above-described various operating modes that may be taken separately or in combination.

[0139] In particular, the flexible bag 2 may include more than four plastic sheets for containing the biopharmaceutical fluid, with each additional sheet likely increasing the integrity of the bag 2 to prevent contamination of the biopharmaceutical fluid it contains.

Claims

1. 1. A testing system (1) for verifying the integrity of a flexible bag (2) using a gas tracer, comprising: - a housing (10) delimiting a vacuum chamber (CH), the housing (10) having an internal volume (10a) that is liquid-tightly isolated from the outside of the housing (10) in an operational configuration of the housing (10); a first helium supply device (3) with a supply pipe (3a) for filling the flexible bag (2) with helium in a filling step, via an outlet (3b) of the supply pipe (3a), when the flexible bag (2) is placed in the vacuum chamber (CH) so as to be surrounded by an internal volume (10a); - a vacuum suction assembly (P1, P3) for performing vacuum suction and extracting gas from the interior volume (10a) outside the flexible bag (2) in a suction mode; at least one pressure measuring member (9) for detecting the helium partial pressure in a detection area (10d) of the internal volume (10a), said detection area (10d) being in communication with a suction inlet of a vacuum suction assembly (P1, P3); at least one source (4) of pressurized helium intended to be introduced into the flexible bag (2); The test system (1) further comprises: a second helium supply (6) for adding helium (18) in the outer internal volume (10a) of the flexible bag (2), comprising: - different from the supply pipe (3a), in communication with a gas source; said second helium supply device (6) including a supply member (5); - a control unit (13) for controlling the first helium supply device (3) and the second helium supply device (6), said control unit (13) being adapted to trigger the second helium supply device (6) before the first helium supply device (3); an analysis module (15) using information representative of the variation over time of the helium partial pressure detected by the pressure measuring member (9) before and after the filling step, said analysis module (15) being configured to detect a helium leak on the basis of said information.

2. An analysis module (15) is adapted to use the information representative of the variation over time of the helium partial pressure detected by the pressure measuring member (9), after the filling step, in order to obtain a test result representative of the helium partial pressure drop (PD) in the detection area (10d), the analysis module (15) comprising: - using information representative of the helium partial pressure detected by the pressure measuring member (9) after the addition of helium by the second helium supply device (6) when the vacuum suction assembly (P1, P3) is in suction mode, including the period after the filling step; - when the vacuum suction assembly (P1, P3) is in suction mode, before the filling step, determining a background value determined on the basis of information representative of the helium partial pressure detected by the pressure measuring member (9), and then subtracting the determined background value from the raw measurement value; and The system according to claim 1, configured to compare the test result with at least one reference result to determine whether the helium-filled flexible bag (2) has passed the integrity verification.

3. 3. The system according to claim 1 or 2, wherein the second helium supply (6) comprises a valve (V2'), preferably a solenoid valve, upstream of the supply member (5), the supply member (5) having a gas-permeable wall for limiting the rate at which helium is added to the internal volume (10a).

4. 4. The system according to claim 3, wherein the second helium supply (6) comprises an additional valve (V2''), preferably an electromagnetic valve, downstream of the supply member (5).

5. A control unit (3) a first valve (V1) allowing the circulation of helium in the supply pipe (3) during the filling step; and a second valve (V2; V2') allowing the circulation of helium in the supply member (5); The system according to claim 1 or 2, configured to control

6. 6. The system according to claim 3, 4 or 5, wherein the gas permeable wall comprises a microporous and / or mesoporous membrane of silicone rubber or glass (32; 32').

7. 7. The system according to any one of claims 1 to 6, wherein the supply member (5) comprises a tube (32) made of silicone or glass adapted to supply helium by diffusion through a silicone wall of the tube (32).

8. 8. The system of claim 1, wherein the at least one source of pressurized helium (4) is a helium source comprising a single tank outside the internal volume (10a) for containing all the helium to be injected into the vacuum chamber (CH), the single tank being operatively coupled to the first helium supply (3) and the second helium supply (6).

9. - two plates (12, 14) in a spaced relationship, preferably parallel; a housing for receiving a flexible bag (2) between two plates (12, 14), the plates forming restraining plates for restraining the expansion of the flexible bag (2) when it is filled with helium during the filling step; The system according to any one of claims 1 to 8, comprising:

10. A test method using a tracer gas to verify the integrity of a flexible bag (2) to detect the presence of possible holes, comprising: - In the preparation stage: providing a test system (1) including a housing (10) defining a vacuum chamber (CH) adapted to be liquid-tightly isolated from an exterior of the housing in an operational configuration of the housing; providing an injection device suitable for supplying a tracer gas into the vacuum chamber, the tracer gas being preferably helium; placing a flexible bag (2) in a vacuum chamber (CH) and connecting a port (11) of the bag to a supply pipe communicating with a source of inert tracer gas, the tracer gas being preferably helium; performing a vacuum suction to obtain a vacuum outside the flexible bag (2) within the internal volume (10a) of the vacuum chamber (CH); performing a gas tracer injection (18) by supplying a quantity of tracer gas by an injection device into the interior volume (10a) outside the flexible bag (2); - during the test phase, while the vacuum suction is still running: Filling a certain amount of tracer gas into a flexible bag (2) in a filling step; detecting information representative of the partial pressure of the tracer gas outside the flexible bag in the internal volume (10a) by using at least one pressure measuring member (9) to enable detection of this tracer gas escaping from the flexible bag; Then, in a next step, the test result, which is representative of the tracer gas partial pressure drop (PD) in the external internal volume (10a) of the flexible bag (2), obtained using at least one pressure measuring member (9) is compared with at least one reference result in order to identify whether the flexible bag has passed the integrity verification. The test method comprising:

11. A testing method according to claim 10, wherein in the testing phase the comparison between the test result and the reference result is performed in a time slot comprised between 3 and 10 seconds after starting the filling step.

12. The tracer gas is helium and the test method, in the preparation stage, is: - performing a vacuum suction inside the flexible bag (2) in order to empty its internal space (SP); - measuring the partial pressure of helium in a detection area (10d) of the internal volume (10a); - calculating the first derivative of the helium partial pressure in the detection area (10d); Further comprising:

12. The test method according to claim 10 or 11, wherein when the helium partial pressure measured in the detection area (10d) reaches a trigger point, it is checked whether the first derivative of the partial pressure of helium is within a predetermined range between a lower limit and an upper limit, and the injection (18) is performed by the injection device only if the first derivative of the partial pressure of helium is outside the predetermined range.

13. 13. The test method according to claim 10, 11 or 12, wherein the gas tracer is helium and, in a preparation step, a certain amount of helium is supplied into the inner volume (10a) outside the flexible bag (2) after a partial pressure of helium has been measured in the inner volume (10a) below a predetermined threshold value.

14. The gas tracer is helium and the reference result is: - a predefined pressure at a given time after the start of the filling step, or - or a predefined pressure drop threshold value obtained at a given time after the start of the filling step by calculating the time derivative of the helium leak rate detected by at least one pressure measuring member (9) in a detection area (10d) of the internal volume (10a).

15. 15. A test method according to claim 10, 11, 12, 13 or 14, in which the filling step is carried out in order to hold the flexible bag (2) between two expanding limiting plates (12, 14) facing away from each other and adapted not to hinder leakage in the wall (W) of the flexible bag (2) placed against them.

16. a flexible bag (2) constituting or being part of a device under test intended to receive a biopharmaceutical product, the device being provided with several flexible pipes (7, 9a, 9b), each connected to a respective port (11, 12a, 12b) of the device under test, the device being placed in a chamber (CH) before applying a vacuum; 16. The test method according to claim 10, 11, 12, 13, 14 or 15, wherein in the preparation stage, performing vacuum suction means evacuating gas in different suction areas of the housing (10) in order to obtain a vacuum inside and outside the flexible bag (2) in the housing (10).

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