WO2007122201A1 - Method and assembly for determining the pressure prevailing in a package - Google Patents

Method and assembly for determining the pressure prevailing in a package Download PDF

Info

Publication number
WO2007122201A1
WO2007122201A1 PCT/EP2007/053906 EP2007053906W WO2007122201A1 WO 2007122201 A1 WO2007122201 A1 WO 2007122201A1 EP 2007053906 W EP2007053906 W EP 2007053906W WO 2007122201 A1 WO2007122201 A1 WO 2007122201A1
Authority
WO
WIPO (PCT)
Prior art keywords
package
measurement chamber
rigid element
pressure
substantially rigid
Prior art date
Application number
PCT/EP2007/053906
Other languages
French (fr)
Inventor
L. C. Aarts
Original Assignee
Interprise Brussels S.A.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Interprise Brussels S.A. filed Critical Interprise Brussels S.A.
Publication of WO2007122201A1 publication Critical patent/WO2007122201A1/en

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65B—MACHINES, APPARATUS OR DEVICES FOR, OR METHODS OF, PACKAGING ARTICLES OR MATERIALS; UNPACKING
    • B65B31/00—Packaging articles or materials under special atmospheric or gaseous conditions; Adding propellants to aerosol containers
    • B65B31/04—Evacuating, pressurising or gasifying filled containers or wrappers by means of nozzles through which air or other gas, e.g. an inert gas, is withdrawn or supplied
    • B65B31/046—Evacuating, pressurising or gasifying filled containers or wrappers by means of nozzles through which air or other gas, e.g. an inert gas, is withdrawn or supplied the nozzles co-operating, or being combined, with a device for opening or closing the container or wrapper
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65B—MACHINES, APPARATUS OR DEVICES FOR, OR METHODS OF, PACKAGING ARTICLES OR MATERIALS; UNPACKING
    • B65B31/00—Packaging articles or materials under special atmospheric or gaseous conditions; Adding propellants to aerosol containers
    • B65B31/04—Evacuating, pressurising or gasifying filled containers or wrappers by means of nozzles through which air or other gas, e.g. an inert gas, is withdrawn or supplied
    • B65B31/08—Evacuating, pressurising or gasifying filled containers or wrappers by means of nozzles through which air or other gas, e.g. an inert gas, is withdrawn or supplied the nozzle being adapted to pierce the container or wrapper
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
    • G01M3/00—Investigating fluid-tightness of structures
    • G01M3/02—Investigating fluid-tightness of structures by using fluid or vacuum
    • G01M3/26—Investigating fluid-tightness of structures by using fluid or vacuum by measuring rate of loss or gain of fluid, e.g. by pressure-responsive devices, by flow detectors
    • G01M3/32—Investigating fluid-tightness of structures by using fluid or vacuum by measuring rate of loss or gain of fluid, e.g. by pressure-responsive devices, by flow detectors for containers, e.g. radiators
    • G01M3/3236—Investigating fluid-tightness of structures by using fluid or vacuum by measuring rate of loss or gain of fluid, e.g. by pressure-responsive devices, by flow detectors for containers, e.g. radiators by monitoring the interior space of the containers
    • G01M3/3272—Investigating fluid-tightness of structures by using fluid or vacuum by measuring rate of loss or gain of fluid, e.g. by pressure-responsive devices, by flow detectors for containers, e.g. radiators by monitoring the interior space of the containers for verifying the internal pressure of closed containers
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
    • G01M3/00—Investigating fluid-tightness of structures
    • G01M3/02—Investigating fluid-tightness of structures by using fluid or vacuum
    • G01M3/36—Investigating fluid-tightness of structures by using fluid or vacuum by detecting change in dimensions of the structure being tested
    • G01M3/366—Investigating fluid-tightness of structures by using fluid or vacuum by detecting change in dimensions of the structure being tested by isolating only a part of the structure being tested

Definitions

  • the invention relates to a method for determining the pressure prevailing a package, such as a vacuum package filled with a product such as nuts, wherein the package is at least partly manufactured from packaging film.
  • the invention also relates to a method for determining whether a package is leaky.
  • the invention further relates to an assembly of a package and a rigid element suitable for carrying out such a method, a kit of parts comprising a measurement chamber and a rigid element.
  • a method for determining the pressure prevailing in a package is known in the art, wherein the package is placed in a vacuum chamber. A vacuum is then created in an inner volume within the vacuum chamber.
  • the vacuum chamber also comprises a pressure sensor for measuring the pressure prevailing in the vacuum chamber. When the vacuum chamber is being evacuated, the variation in pressure in the vacuum chamber is subsequently monitored for a certain period. The pressure at which the pack bulges is detected. The pressure prevailing in the package is thus determined, albeit indirectly.
  • the chamber can be ventilated again. Once the package has been back in an atmospheric environment for some time, the pressure in the package will rise as a result of any leak. Repeating the first pressure measurement allows the increase in pressure to be measured and a leak to be detected.
  • the bulging of the package is not only caused by the decrease of pressure around the package, but also by an outwardly directed force of the packed product that has been compressed by atmospheric pressure and wants to regain its original volume.
  • a further disadvantage is that the entire package must be placed in an airtight compartment, which is extremely impractical in the case of bulk packages of, for example, 1,000 litres.
  • the above method can be used for measuring leaks by performing the measurement twice and, where applicable, determining a pressure difference and using this as a leak indicator.
  • a large waiting time must be present between the first and second measurement.
  • the present invention concerns a method for determining the pressure prevailing in a package suitable for holding a vacuum and filled with a product, wherein said package is at least partially made of a packaging film, said method comprising the following steps:
  • the package is at least partially made of packaging film, and wherein a substantially rigid element, comprising a first and second main surfaces separated by the element's thickness and comprising at least one opening fluidly connecting said first main surface to said second main surface, is positioned in the interior of the package, such that the first main surface of the rigid element substantially contacts the inner surface of the packaging film.
  • the rigid element is fixed to the packaging film by e.g., welding, gluing, etc.
  • a kit of parts which is suitable for carrying out the above method, comprising:
  • a substantially rigid element comprising a first and second main surfaces separated by the element's thickness and comprising at least one opening fluidly connecting said first main surface to said second main surface;
  • a measurement chamber comprising an inner volume with a suction opening which perimeter fits into the perimeter of the rigid element; wherein the perimeter of the measurement chamber can rest on a film laid on one of the first and second main surfaces of the rigid element to define a gas tight inner volume.
  • the substantially rigid element defined above can be used for determining the pressure prevailing in a package at least partially made of a packaging film and: or to determine whether t comprises a leak.
  • Fig. 1 shows a schematic representation of a first embodiment of a device for determining a pressure prevailing in at least one package
  • Fig. 2 shows an example of a variation in pressure in the measurement chamber over time
  • Fig. 3 shows a schematic representation of a second embodiment of a device for determining a pressure prevailing in at least one package
  • Fig. 4 shows a schematic representation of a third embodiment of a device for determining a pressure prevailing in at least one package
  • Fig. 5a shows a schematic representation of a fourth embodiment of a device for determining a pressure prevailing in at least one package in a first state
  • Fig. 5b shows the device of Fig. 5a in a second state .
  • Fig. 6 shows the pressure evolution in the inner volume, Pi, in the volume filled with an incompressible fluid, V 2 , and in the package, P 1n , as the inner volume is being evacuated using a device as depicted in Figure 5.
  • Fig. 1 shows a schematic representation of a first embodiment of a device (1) for determining a pressure prevailing in at least one package.
  • Fig. 1 shows a package
  • the package (2) containing a product (4) .
  • the package also contains a fluid, such as air.
  • the pressure of the fluid in the package is less than atmospheric pressure.
  • the package (2) thus forms a vacuum package.
  • the package (2) is at least partly manufactured from a packaging film (6) .
  • the film (6) is, for example, flexible and/or elastic.
  • a substantially rigid element (8) is placed against an inner side of the film (6) .
  • the substantially rigid element (8) is designed as a plate, for example a round disc.
  • the substantially rigid element (8) has a perforation (10) .
  • a measurement chamber (12) is placed against an outer side of the package (2) .
  • the measurement chamber (12) comprises a rigid housing, an opening, and is provided with a sealing rim (14) round the edge of the opening.
  • an inner volume (16) of the measurement chamber (12) is a fluid communication with a pressure sensor 18 via a connection.
  • the inner volume (16) of the measurement chamber (12) is in a fluid communication with an, e.g. pneumatic, valve (22), a flow restriction (24) and a vacuum pump (26) .
  • the device described thus far can be used as follows to determine the pressure prevailing in a package.
  • the opening of the measurement chamber (12) is pressed against the substantially rigid element (8), and is separated therefrom by at least part of the packaging film
  • the film (6) is thus, at least partly, arranged between the measurement chamber (12) and the substantially rigid element (8) .
  • the valve (22) is opened and the vacuum pump (26) switched on.
  • the vacuum pump (26) will lower the pressure in the inner volume (16) of the measurement chamber (12) .
  • the pressure in the measurement chamber (12) will decrease until the pressure in the measurement chamber (12) is substantially equal to the pressure in the package
  • Fig. 1 shows the bulging film (6) with the dotted line 6' . If the volume of the inner volume (16) of the measurement chamber (12) enclosed by the package (2) and the measurement chamber (12) is considerably smaller than the volume of the package (2), the pressure in the measurement chamber (12) will substantially remain constant while the film (6) is bulging. Then, the pressure in the measurement chamber (12) is substantially equal to the pressure in the package (2) .
  • the pressure in the measurement chamber (12) is determined while the film (6) is bulging, but is not touching the inner wall of the measurement chamber. After all, the pressure in the measurement chamber (12) is then substantially equal to the pressure in the package (2) .
  • the device shown in Fig. 1 it is possible to determine whether the film (6) is bulging by means of the displacement sensor (20) . It will be appreciated that it is also possible to determine whether the film (6) is bulging from the variation in the pressure in the measurement chamber (12) over time. For example, thereto the signal from the pressure sensor 18 can be transmitted to a differentiating circuit. When the film (6) begins to bulge, the pressure in the measurement chamber (12) remains substantially constant, and an output signal of the differentiating circuit then turns to zero.
  • Fig. 2 shows an example of the variation in the pressure in the measurement chamber (12) over time, while the inner volume (16) of the measurement chamber is being evacuated.
  • ti the pressure in the measurement chamber (12) decreases.
  • t2 the pressure in the measurement chamber (12) remains substantially constant.
  • ts the pressure in the measurement chamber (12) decreases.
  • the second period t2 is associated with the period during which the film (6) is bulging in the measurement chamber (12), but is not touching the inner wall of the measurement chamber.
  • the pressure in the measurement chamber (12) is therefore substantially equal to the pressure in the package (2) .
  • the valve (22) If after draining the inner volume (16) of the measurement chamber (12) the valve (22) is closed, the pressure in the measurement chamber, and with it the pressure in the package (2), can be followed and any leak in the package detected. Tests have shown that a variation in pressure of 1/100 mbar over 10 seconds can be measured. At a variation in pressure of 1/100 mbar due to a leak a package, calculated from an initial pressure of 50 mbar, will become soft after 20 days. In this case, the greater the area of that part of the film (6) that is arranged between the measurement chamber (12) and the substantially rigid element (8), the greater the sensitivity to changes in pressure.
  • a displacement of the film (6) can also be detected in other ways, for example by means of a capacitive sensor.
  • the capacitive sensor has the advantage that no mechanical loading of the film (6) is necessary.
  • substantially rigid when referring to element (8) in the present context means that the element should have structural properties sufficient to ensure a smooth enough contact surface on the packaging film (6) to form a gas tight contact with the opening of the measuring device (12) .
  • the substantially rigid element (8) can, for instance, comprise a plastic plate. The plate thickness depends on the stiffness required to ensure a smooth surface, which varies depending on the type of product contained in the package, e.g., ground coffee and nuts do not require the same stiffness. Typically, the thickness of the substantially rigid element may be comprised between 0.5 and 5 mm, preferably 1 and 4 mm, most preferably 1 to 3 mm.
  • the substantially rigid element is substantially designed as a plate-shaped body, which perimeter forms a disc, ellipse, polygon with or without rounded corners, or any customized shape specially adapted to the geometry of the package (2) .
  • the substantially rigid element is round disk.
  • a surface of the substantially rigid element is such that it can seal the suction opening.
  • the substantially rigid element comprises a substantially rigid support member comprising at least one aperture, and a filter laminated on the second main surface of said support member, facing away from the packaging film, said filter being permeable to the fluid and substantially impermeable to the product contained in the package.
  • a substantially rigid support member comprising at least one aperture
  • a filter laminated on the second main surface of said support member facing away from the packaging film, said filter being permeable to the fluid and substantially impermeable to the product contained in the package.
  • the second surface of the substantially rigid element facing away from the packaging film, is provided with at least one groove in fluid communication with the at least one opening of the element.
  • the groove substantially prevents the fluid connection between the first and second main surfaces of the substantially rigid element from being sealed off by the product. If the package contains a coarse-grained product, the coarse grains will abut against upright walls of at the least one groove, but are unable to completely seal off said groove, so that the fluid connection remains open. If the package contains a fine-grained product, this product will substantially form a porous mass, which will not seal off the fluid connection.
  • a filter which is permeable to the fluid and substantially impermeable to the product is fixed to said second surface of the substantially rigid element, which is provided with at least one groove in fluid communication with the at least one opening of the element.
  • This laminated geometry is particularly advantageous in that it optimizes the air flow through the rigid element while preventing the passage of the finest powder particles. This effect is enhanced if a network of grooves covering the entire area of said second surface is in fluid communication with the at least one opening. Any structured surface forming a fluid communication network connected to the at least one opening can be envisaged.
  • the measurement chamber (12) can, for example, be round.
  • the size of the opening depends on the size of the package to be tested, and can, for example, have a diameter of approximately between 20 and 100 mm, preferably 25 and 50 mm and a depth of 0.5 to 10 mm, preferably, 1 to 5 mm, more preferably of 1 to 3 mm.
  • Fig. 3 shows a schematic representation of a second embodiment of a device for determining the pressure prevailing in at least one package.
  • the measurement chamber (12) includes a perforating device.
  • the perforating device comprises a needle 30.
  • the needle 30 is connected to a movement device (32) for moving the needle 30.
  • the movement device (32) is designed as a pneumatic cylinder whose cylinder rod can be moved up and down by means of air valves (34) and (36) .
  • the needle is connected to the cylinder rod.
  • the substantially rigid element (8) has the perforation (10), going through the substantially rigid element (8), and a blind hole (38).
  • the blind hole (38) is situated on the side of the substantially rigid element facing the film (6), and preferably is situated in a position that lies on a (virtual) line along which the needle 30 can be moved.
  • the substantially rigid element is connected fluid-tightly to the film (6) along its peripheral edge, for example by means of a seal seam.
  • the device (1) shown in Fig. 3 can be used as follows to carry out the method for determining a pressure prevailing in at least one package.
  • the measurement chamber (12) is placed against the substantially rigid element (8), so that the film (6) is at least partly arranged between the substantially rigid element (8) and the measurement chamber (12) .
  • An initial check can now be made to see whether the measurement chamber abuts against the package (2) fluid-tightly, for example air- tightly.
  • the valve (22) is opened and a partial vacuum created in the inner volume (16) of the measurement chamber 2 by means of the pump (26) .
  • the pressure in the measurement chamber is determined by means of pressure sensor 18.
  • the valve (22) is then closed. If the pressure in the measurement chamber (12) substantially remains constant, it can be concluded that the measurement chamber is applied fluid-tightly.
  • the needle 30 is subsequently pushed through the film (6) by means of the movement device (32) to create a perforation.
  • the blind hole (38) in the substantially rigid element (8) facilitates the formation of the perforation.
  • the needle 30 can then be moved again so that the needle does not remain in the film (6) .
  • the pressure in the measurement chamber (12) is higher than the, expected, pressure in the package, for example approximately 800 mbar. In that case the pressure in the measurement chamber will ensure that the film is substantially abuts against the substantially rigid body. If fluid-sealing paste (for example, air-sealing paste) is applied around the blind hole
  • the pressure in the measurement chamber (12) is reduced using the pump (26) to such an extent that the film (6) bulges.
  • the film (6) comes loose from the substantially rigid element (8), creating a fluid connection between the inner volume (16) of the measurement chamber (12) via the perforation (10) with the inner volume of the package (2) .
  • the valve (22) is closed.
  • the pressure in the measurement chamber (12) will then become substantially equal to the pressure in the package (2), because fluid flows from the measurement chamber into the package or from the package into the measurement chamber. If no fluid flows, and the pressure in the measurement chamber remains substantially constant, the pressure in the measurement chamber can be determined, for example using pressure sensor 18. It is further possible to follow a variation in the pressure in the measurement chamber (12) to be able to detect a possible leak in the package (2) .
  • the pressure in the measurement chamber can be increased.
  • the pressure in the measurement chamber is increased quickly, for example by means of opening a valve (40), which is connected to air under atmospheric pressure, wherein the valve (40) has a much larger throughput for air than the perforation in the film (6) . If the pressure in the measurement chamber (12) is increased very quickly, the film (6) is pressed against the substantially rigid element, thereby sealing through-going perforation (10). If necessary, using the pump (26), a partial vacuum is applied to the inner volume (16) of the measurement chamber (12) at a higher pressure than the partial vacuum in the package (2) to measure (using the pressure sensor 18) whether the perforation (10) is sealed.
  • the film (6) around the blind hole (38) can be connected to the substantially rigid element fluid-tightly, for example by means of a seal seam, so that no fluid connection is created via the perforation between the inner volume of the package and an environment.
  • the perforation can also be sealed on the outer side of the package, for example taped up, for example with airtight tape .
  • Fig. 4 shows a schematic representation of a third embodiment of a device for determining the pressure prevailing in at least one package.
  • the device (1) shown in Fig. 4 substantially corresponds to the device shown in Fig. 3.
  • the device shown in Fig. 4 is further fitted with sealing means (42) .
  • the seals (42) are designed as a seal-ring for welding the film to the substantially rigid element (8) .
  • the seal-ring is connected to the rod of the cylinder.
  • the device (1) shown in Fig. 4 can be used to carry out the method for determining the pressure prevailing in at least one package according to what has been explained in relation to Fig. 3.
  • the seal ring If the needle 30 is moved forwards and backwards by means of the movement device (32) for perforating the film, the seal ring is cold and the film (6) cannot yet adhere to the substantially rigid element (8). Once the measurement has been made, using the movement device (32), the seal-ring, which is now heated, presses the film (6) against the substantially rigid element. When the film (6) around the blind hole (38) has been welded fluid-tightly, the seal-ring can be removed from the film (6) using the movement device.
  • the pressure in the measurement chamber (12) can be increased to e.g. 800 mbar, for example by opening and then closing the valve (40) . It is then possible to determine, for example using the pressure sensor 18, whether the perforation in the film is actually sealed.
  • the pressure in the measurement chamber (12) can be increased such that the measurement chamber can be removed.
  • the needle 30 can also be a hollow needle which is in a fluid communication with the inner volume (16) of the measurement chamber (12) .
  • the substantially rigid element (8) can be manufactured from a material that can be pierced by the needle 30, such as a substantially rigid rubber.
  • the hollow needle and/or the substantially rigid element (8) are dimensioned such that the hollow needle completely pierces the substantially rigid element (8), so that the hollow needle forms a fluid connection between the inner volume of the package (2) and the inner volume (16) of the measurement chamber (12) .
  • the perforation (10) is made in the substantially rigid element (8) beforehand. It is also possible for the material of the substantially rigid element (8) to be chosen such that the perforation formed by the needle 30 closes once the needle is removed from the substantially rigid element.
  • the Package (2) is thus substantially sealed fluid-tightly once the needle 30 is removed.
  • Figs. 5a and 5b show schematic representations of a particularly advantageous embodiment of a device for determining the pressure prevailing in a package.
  • the opening of the measurement chamber (12) is sealed with a flexible membrane (44) defining a first inner volume
  • the measurement chamber (12) is sealingly abutted to the outer surface of the packaging film (6) such that the perimeter (14) of the suction device's opening rests entirely on the rigid element (8) separated therefrom by the thickness of the packaging film (6); a second, thin volume
  • FIG. (16) is thus defined between the membrane (44) and the packaging film (6) .
  • Said second volume (16) is evacuated with means (52) for making vacuum, such as for example a vacuum pump.
  • Figure 6 illustrates how, as the pressure, Pi, in said second volume (16) is reduced by actuating a vacuum pump
  • the packaging film (6) starts bulging, thus reducing the volume (16) and momentarily stabilizing the pressures, Pi, and, V 2 , in volumes (16) and (54), respectively.
  • This process goes on until the packaging film (6) contacts the membrane (44) and the thus formed interface grows as the second volume (16) becomes smaller, until the packaging film (6) cannot be strained further.
  • the pressure, V 2 in the volume (54) filled with an incompressible liquid (46), equilibrates with the pressure, P 1n , prevailing in the package.
  • the membrane (44) should be positioned with respect to the device's opening such as to minimize the depth of the second volume (16) formed upon application of the measuring device against the packaging film (6) .
  • the speed and accuracy of the pressure measurement increase as the depth of volume
  • the optimal distance of the membrane (44) to the device's opening depends on the opening size and the flexibility of the packaging film (6), and the system must be designed to allow substantial contact between the membrane (44) and the packaging film (6) as the pressure, Pi, in volume (16) decreases below the pressure, P 1n , in the package.
  • the membrane (44) is fixed to the measuring device at a distance from the opening thereof comprised between 0.5 and 5 mm, preferably; 0.5 and 3 mm, most preferably 0.5 and 2 mm. The measurement can be very quick, in a matter of a fraction of a second, which renders this embodiment particularly advantageous for the pressure measurement in packages produced in a large scale.
  • the accuracy can be as fine as 0.01 mbar. This means that with a 1 min test, wherein the pressure in the volume (54) is balanced with the one in the package as described above, the vacuum pump is switched off and the pressure evolution monitored, one can determine a leak in the package leading to a 500 mbar loss of pressure in about 35 days. Alternatively, two measurements, each requiring less than a second, may be performed at different intervals, and the difference between the pressures obtained at these two intervals can be extrapolated to determine the vacuum "life" in the package.
  • the invention is in no way limited to the examples shown in the figures.
  • the substantially rigid element (8) can abut against the inside of the package (2) free from mechanical connections.
  • the substantially rigid element (8) can also be joined to the package (2), for example glued or sealed. It is important here that at least part of the film (6) is free from any mechanical connection with the substantially rigid element (8), so that the film can bulge as described above.
  • the substantially rigid element can be provided with a surface structure on the side adjacent to the package (2) .
  • the substantially rigid element (8) can be corrugated. While packaging the product (4) the film (6) can abut against the substantially rigid element under the influence of vacuum pressure and follow the surface structure.
  • the film that is flat prior to packing can become deformed against the substantially rigid element, for example into a corrugated membrane.
  • the deformed film can bulge more easily if the pressure in the measurement chamber (12) is substantially equal to the pressure in the package (2) . This allows a greater sensitivity to be achieved, or a smaller substantially rigid element to be used. It should be pointed out that the ⁇ bulging' of the film
  • the substantially rigid element (6) can also include the turning flat of the film (6), for example by its coming loose from the surface structure. It is also possible for the substantially rigid element to have a surface structure on the side facing away from the package. This substantially prevents the products from sliding along the substantially rigid element. This has the advantage of reducing the chance of the product in the package blocking the perforation in the substantially rigid element . In the examples the substantially rigid element substantially abuts against the package across its entire surface. It is also possible for the substantially rigid element to have a lowered section, so that the fluid in the package is present between the film and at least part of the substantially rigid element. The film can thus bulge very easily, as the film cannot remain stuck to the substantially rigid element.
  • the substantially rigid element is provided with a single through-going perforation (10).
  • the substantially rigid element can also be designed as a grid or as a plate comprising an open porosity.
  • the substantially rigid element can also be designed as a grid or as a plate comprising an open porosity.
  • the substantially rigid element can also be designed as a grid or as a plate comprising an open porosity.
  • the substantially rigid element can also have at least one groove in the side of the substantially rigid element adjacent to the package, to allow the fluid in the package to flow through the groove to the volume between the film and the substantially rigid element, for example if the film bulges.
  • the substantially rigid element (8) is provided with text, for example if the film (6) is substantially transparent.
  • the substantially rigid element (8) is provided with identifying marks that allow the measurement chamber, for example a transparent measurement chamber, to be placed on the substantially rigid element positioned correctly, for example centred. Identifying marks can also be applied that can be read by a measuring robot in an automated system. If opaque film is used, an identifying mark can be applied to the outer side of the package to relocate a position of the substantially rigid element.
  • the present invention can be applied to a broad selection of products varying in size and texture.
  • it can be applied to any product being solid, powdery, pasty or liquid, which packing under vacuum permits the conservation, volume reduction, integrity (e.g., against counterfeit), protection against moisture, insects, oxidation, contamination, stain, pollution, etc. of said product.
  • the product may belong to any of the groups of foodstuff, consumer's goods, pharmaceutical, cosmetics, healthcare, hygiene, and industrial products.
  • foodstuff comprise without being restricted to drinks, powders of reconstitution for drinks, egg based, meat, fruit, vegetable, spices, food additives like dyes, binders, coagulants flour; yeast, infants' food, dietetic and organic products, cooked preparations; seafood, dairy products, frozen products, animal food, etc.
  • consumer's goods include textile; cloths, linen, house and office equipment, documents, paper, banknotes, artwork, electronic components, and the like.
  • Pharmaceutical, cosmetics, healthcare, and hygiene products include inter alia medicines and treating products in the form of pastes, creams, pills, tablets, powders, liquids, syrups.
  • industrial products comprise cleaning products, parts for any type of equipment in the field of transportation, electricity, electronics, manufacturing, chemistry; heavy industry, agriculture, like seeds and fertilizers, packaging, like corks for wine bottles, etc. It can also be used to apply vacuum to a package containing packed goods for saving space and hence transportation and storage costs.
  • the applications are infinite and they can be implemented at a small, laboratory scale to large industrial sizes, passing through all the intermediate scales from domestic and office applications to small and medium companies needs. All it requires is to adapt the size and power of the pump to the size of the package.
  • the claimed method is simple to carry out and can be applied to large series as well as to occasional uses.

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Chemical & Material Sciences (AREA)
  • Dispersion Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Examining Or Testing Airtightness (AREA)
  • Packages (AREA)
  • Measuring Fluid Pressure (AREA)

Abstract

Method and assembly for determining the pressure prevailing in a package, such as a vacuum pack filled with nuts, wherein the package is at least partly manufactured from packaging film, wherein the package is provided with a substantially rigid element that on an inner side of the package substantially lies in contact with the packaging film, wherein use is made of a measurement chamber that has an open side, wherein the open side sealingly abuts against an outer side of the package, on a location where the substantially rigid element substantially abuts against the inner side of the package, thus forming an enclosed volume between the measurement chamber and the package, wherein the pressure in the measurement chamber is substantially made equal to the pressure in the package and wherein subsequently the pressure in the measurement chamber is then determined.

Description

Method and assembly for determining the pressure prevailing in a package.
FIELD OF THE INVENTION
The invention relates to a method for determining the pressure prevailing a package, such as a vacuum package filled with a product such as nuts, wherein the package is at least partly manufactured from packaging film. The invention also relates to a method for determining whether a package is leaky.
The invention further relates to an assembly of a package and a rigid element suitable for carrying out such a method, a kit of parts comprising a measurement chamber and a rigid element.
BACKGROUND OF THE INVENTION
A method for determining the pressure prevailing in a package is known in the art, wherein the package is placed in a vacuum chamber. A vacuum is then created in an inner volume within the vacuum chamber. The vacuum chamber also comprises a pressure sensor for measuring the pressure prevailing in the vacuum chamber. When the vacuum chamber is being evacuated, the variation in pressure in the vacuum chamber is subsequently monitored for a certain period. The pressure at which the pack bulges is detected. The pressure prevailing in the package is thus determined, albeit indirectly.
Once the pressure in the package has been determined, the chamber can be ventilated again. Once the package has been back in an atmospheric environment for some time, the pressure in the package will rise as a result of any leak. Repeating the first pressure measurement allows the increase in pressure to be measured and a leak to be detected.
However, there are disadvantages to said method. When determining the pressure, the drop in pressure must occur not too fast, as otherwise the detection of the point at which the package bulges cannot be determined with sufficient accuracy. The measurement therefore takes a long time .
The bulging of the package is not only caused by the decrease of pressure around the package, but also by an outwardly directed force of the packed product that has been compressed by atmospheric pressure and wants to regain its original volume. A further disadvantage is that the entire package must be placed in an airtight compartment, which is extremely impractical in the case of bulk packages of, for example, 1,000 litres.
The above method can be used for measuring leaks by performing the measurement twice and, where applicable, determining a pressure difference and using this as a leak indicator. However, because of the inaccuracy of the method used a large waiting time must be present between the first and second measurement. It results from the foregoing that there remains a need in the art for a method allowing to determine the pressure prevailing in a package and/or to determine whether the package comprises a leak, which is simple, reliable; accurate, quick, and cheap. The present invention offers all the foregoing advantages over the prior art. SUMMARY OF THE INVENTION
The present invention is defined in the appended independent claims. Preferred embodiments are defined in the dependent claims. In particular, the present invention concerns a method for determining the pressure prevailing in a package suitable for holding a vacuum and filled with a product, wherein said package is at least partially made of a packaging film, said method comprising the following steps:
(a) providing a package containing in its interior a product and a substantially rigid element comprising a first and second main surfaces separated by the element's thickness and comprising at least one opening fluidly connecting said first main surface to said second main surface, said substantially rigid element being positioned such that said first main surface thereof substantially lies in contact with the inner surface of the packaging film;
(b) providing a measurement chamber comprising an inner volume with a suction opening which perimeter fits into the perimeter of the rigid element;
(c) sealingly abutting the measurement chamber to the outer surface of the packaging film such that the perimeter of the suction device's opening rests entirely on the rigid element separated therefrom by the thickness of the packaging film;
(d) reducing the pressure in the measurement chamber until the pressure in the inner volume of the measurement chamber is substantially the same as the one inside the package; (e) determining the pressure in the inner volume of the measurement chamber. It also concerns a package suitable for performing a method as described above wherein the package is at least partially made of packaging film, and wherein a substantially rigid element, comprising a first and second main surfaces separated by the element's thickness and comprising at least one opening fluidly connecting said first main surface to said second main surface, is positioned in the interior of the package, such that the first main surface of the rigid element substantially contacts the inner surface of the packaging film. Preferably, the rigid element is fixed to the packaging film by e.g., welding, gluing, etc.
A kit of parts is described which is suitable for carrying out the above method, comprising:
(a) a substantially rigid element comprising a first and second main surfaces separated by the element's thickness and comprising at least one opening fluidly connecting said first main surface to said second main surface; and
(b) a measurement chamber comprising an inner volume with a suction opening which perimeter fits into the perimeter of the rigid element; wherein the perimeter of the measurement chamber can rest on a film laid on one of the first and second main surfaces of the rigid element to define a gas tight inner volume. Finally, the substantially rigid element defined above can be used for determining the pressure prevailing in a package at least partially made of a packaging film and: or to determine whether t comprises a leak..
The invention will now be explained in greater detail by means of the drawing and detailed description. DESCRIPTION OF THE DRAWINGS
Fig. 1 shows a schematic representation of a first embodiment of a device for determining a pressure prevailing in at least one package; Fig. 2 shows an example of a variation in pressure in the measurement chamber over time;
Fig. 3 shows a schematic representation of a second embodiment of a device for determining a pressure prevailing in at least one package; Fig. 4 shows a schematic representation of a third embodiment of a device for determining a pressure prevailing in at least one package;
Fig. 5a shows a schematic representation of a fourth embodiment of a device for determining a pressure prevailing in at least one package in a first state; and
Fig. 5b shows the device of Fig. 5a in a second state .
Fig. 6 shows the pressure evolution in the inner volume, Pi, in the volume filled with an incompressible fluid, V2, and in the package, P1n, as the inner volume is being evacuated using a device as depicted in Figure 5.
DETAILED DESCRIPTION OF THE INVENTION
Fig. 1 shows a schematic representation of a first embodiment of a device (1) for determining a pressure prevailing in at least one package. Fig. 1 shows a package
(2) containing a product (4) . The package also contains a fluid, such as air. Preferably, the pressure of the fluid in the package is less than atmospheric pressure. The package (2) thus forms a vacuum package. The package (2) is at least partly manufactured from a packaging film (6) . The film (6) is, for example, flexible and/or elastic. A substantially rigid element (8) is placed against an inner side of the film (6) . In this example the substantially rigid element (8) is designed as a plate, for example a round disc. In the example the substantially rigid element (8) has a perforation (10) .
A measurement chamber (12) is placed against an outer side of the package (2) . In this example the measurement chamber (12) comprises a rigid housing, an opening, and is provided with a sealing rim (14) round the edge of the opening. In this example an inner volume (16) of the measurement chamber (12) is a fluid communication with a pressure sensor 18 via a connection. A displacement sensor
(20) may be fitted to an inner side of the measurement chamber (12) . In Fig. 1, the inner volume (16) of the measurement chamber (12) is in a fluid communication with an, e.g. pneumatic, valve (22), a flow restriction (24) and a vacuum pump (26) .
The device described thus far can be used as follows to determine the pressure prevailing in a package. The opening of the measurement chamber (12) is pressed against the substantially rigid element (8), and is separated therefrom by at least part of the packaging film
(6) . The film (6) is thus, at least partly, arranged between the measurement chamber (12) and the substantially rigid element (8) . Subsequently, the valve (22) is opened and the vacuum pump (26) switched on. The vacuum pump (26) will lower the pressure in the inner volume (16) of the measurement chamber (12) . The pressure in the measurement chamber (12) will decrease until the pressure in the measurement chamber (12) is substantially equal to the pressure in the package
(2) . As soon as the pressure in the measurement chamber
(12) is equal to the pressure in the package (2), further evacuating the measurement chamber (12) using the pump (26) results in bulging of the film (6) . Here, some of the fluid in the package (2) will flow through the perforation (10) . In this example the film (6) bulges in the direction of the measurement chamber (12), away from the substantially rigid element (8) . Fig. 1 shows the bulging film (6) with the dotted line 6' . If the volume of the inner volume (16) of the measurement chamber (12) enclosed by the package (2) and the measurement chamber (12) is considerably smaller than the volume of the package (2), the pressure in the measurement chamber (12) will substantially remain constant while the film (6) is bulging. Then, the pressure in the measurement chamber (12) is substantially equal to the pressure in the package (2) .
If evacuating of the measurement chamber (12) is continued once the film (6) has started bulging, the film (6) will abut against an inner wall of the measurement chamber (12) . Once the film abuts against the inner wall, continued evacuating of the measurement chamber (12) will result in a decrease in the pressure in the measurement chamber.
Preferably, therefore, to determine the pressure prevailing in the package (2), the pressure in the measurement chamber (12) is determined while the film (6) is bulging, but is not touching the inner wall of the measurement chamber. After all, the pressure in the measurement chamber (12) is then substantially equal to the pressure in the package (2) . With the device shown in Fig. 1 it is possible to determine whether the film (6) is bulging by means of the displacement sensor (20) . It will be appreciated that it is also possible to determine whether the film (6) is bulging from the variation in the pressure in the measurement chamber (12) over time. For example, thereto the signal from the pressure sensor 18 can be transmitted to a differentiating circuit. When the film (6) begins to bulge, the pressure in the measurement chamber (12) remains substantially constant, and an output signal of the differentiating circuit then turns to zero.
Fig. 2 shows an example of the variation in the pressure in the measurement chamber (12) over time, while the inner volume (16) of the measurement chamber is being evacuated. During an initial period ti the pressure in the measurement chamber (12) decreases. During a second period t2 the pressure in the measurement chamber (12) remains substantially constant. During a third period ts the pressure in the measurement chamber (12) decreases. As described above, the second period t2 is associated with the period during which the film (6) is bulging in the measurement chamber (12), but is not touching the inner wall of the measurement chamber. During the second period t2 the pressure in the measurement chamber (12) is therefore substantially equal to the pressure in the package (2) .
If after draining the inner volume (16) of the measurement chamber (12) the valve (22) is closed, the pressure in the measurement chamber, and with it the pressure in the package (2), can be followed and any leak in the package detected. Tests have shown that a variation in pressure of 1/100 mbar over 10 seconds can be measured. At a variation in pressure of 1/100 mbar due to a leak a package, calculated from an initial pressure of 50 mbar, will become soft after 20 days. In this case, the greater the area of that part of the film (6) that is arranged between the measurement chamber (12) and the substantially rigid element (8), the greater the sensitivity to changes in pressure.
It will be appreciated that instead of the displacement sensor (20) of Fig. 1 a displacement of the film (6) can also be detected in other ways, for example by means of a capacitive sensor. The capacitive sensor has the advantage that no mechanical loading of the film (6) is necessary.
"Substantially rigid" when referring to element (8) in the present context means that the element should have structural properties sufficient to ensure a smooth enough contact surface on the packaging film (6) to form a gas tight contact with the opening of the measuring device (12) . The substantially rigid element (8) can, for instance, comprise a plastic plate. The plate thickness depends on the stiffness required to ensure a smooth surface, which varies depending on the type of product contained in the package, e.g., ground coffee and nuts do not require the same stiffness. Typically, the thickness of the substantially rigid element may be comprised between 0.5 and 5 mm, preferably 1 and 4 mm, most preferably 1 to 3 mm. The substantially rigid element
(8) is substantially designed as a plate-shaped body, which perimeter forms a disc, ellipse, polygon with or without rounded corners, or any customized shape specially adapted to the geometry of the package (2) . Preferably, the substantially rigid element is round disk. Preferably a surface of the substantially rigid element is such that it can seal the suction opening.
Preferably, the substantially rigid element comprises a substantially rigid support member comprising at least one aperture, and a filter laminated on the second main surface of said support member, facing away from the packaging film, said filter being permeable to the fluid and substantially impermeable to the product contained in the package. Hence, there is no risk that the product inside the package leaks from the package and/or clogs the aperture during measurement. It is thus also possible to measure the pressure in a package containing (very fine) powder, such as, for example, cocoa powder, wherein the powder does not leak from the package and/or clog the aperture. This solution allows a standard base element to be used, comprising at least one aperture of sufficient size and permeability to allow air to be evacuated from the package at a high rate, independently of the content of the package, and to select the filter as a function of the size and properties of the product contained in the package. Preferably, the second surface of the substantially rigid element, facing away from the packaging film, is provided with at least one groove in fluid communication with the at least one opening of the element. The groove substantially prevents the fluid connection between the first and second main surfaces of the substantially rigid element from being sealed off by the product. If the package contains a coarse-grained product, the coarse grains will abut against upright walls of at the least one groove, but are unable to completely seal off said groove, so that the fluid connection remains open. If the package contains a fine-grained product, this product will substantially form a porous mass, which will not seal off the fluid connection.
Most preferably, a filter which is permeable to the fluid and substantially impermeable to the product is fixed to said second surface of the substantially rigid element, which is provided with at least one groove in fluid communication with the at least one opening of the element. This laminated geometry is particularly advantageous in that it optimizes the air flow through the rigid element while preventing the passage of the finest powder particles. This effect is enhanced if a network of grooves covering the entire area of said second surface is in fluid communication with the at least one opening. Any structured surface forming a fluid communication network connected to the at least one opening can be envisaged.
The measurement chamber (12) can, for example, be round. The size of the opening depends on the size of the package to be tested, and can, for example, have a diameter of approximately between 20 and 100 mm, preferably 25 and 50 mm and a depth of 0.5 to 10 mm, preferably, 1 to 5 mm, more preferably of 1 to 3 mm. Fig. 3 shows a schematic representation of a second embodiment of a device for determining the pressure prevailing in at least one package. In the embodiment in Fig. 3 the measurement chamber (12) includes a perforating device. In this example the perforating device comprises a needle 30. In this example the needle 30 is connected to a movement device (32) for moving the needle 30. In Fig. 3 the movement device (32) is designed as a pneumatic cylinder whose cylinder rod can be moved up and down by means of air valves (34) and (36) . The needle is connected to the cylinder rod. In Fig. 3 the substantially rigid element (8) has the perforation (10), going through the substantially rigid element (8), and a blind hole (38). The blind hole (38) is situated on the side of the substantially rigid element facing the film (6), and preferably is situated in a position that lies on a (virtual) line along which the needle 30 can be moved. In this example the substantially rigid element is connected fluid-tightly to the film (6) along its peripheral edge, for example by means of a seal seam.
The device (1) shown in Fig. 3 can be used as follows to carry out the method for determining a pressure prevailing in at least one package.
The measurement chamber (12) is placed against the substantially rigid element (8), so that the film (6) is at least partly arranged between the substantially rigid element (8) and the measurement chamber (12) . An initial check can now be made to see whether the measurement chamber abuts against the package (2) fluid-tightly, for example air- tightly. To do this, the valve (22) is opened and a partial vacuum created in the inner volume (16) of the measurement chamber 2 by means of the pump (26) . The pressure in the measurement chamber is determined by means of pressure sensor 18. The valve (22) is then closed. If the pressure in the measurement chamber (12) substantially remains constant, it can be concluded that the measurement chamber is applied fluid-tightly. To determine the pressure in the package (2), the needle 30 is subsequently pushed through the film (6) by means of the movement device (32) to create a perforation. The blind hole (38) in the substantially rigid element (8) facilitates the formation of the perforation. The needle 30 can then be moved again so that the needle does not remain in the film (6) .
Preferably before the film is perforated the pressure in the measurement chamber (12) is higher than the, expected, pressure in the package, for example approximately 800 mbar. In that case the pressure in the measurement chamber will ensure that the film is substantially abuts against the substantially rigid body. If fluid-sealing paste (for example, air-sealing paste) is applied around the blind hole
(38), or if the surface of the substantially rigid element
(8) around the blind hole (38) is very smooth, because the film is pressed against the substantially rigid element substantially no fluid communication will be created between an inner volume of the package and the inner volume (16) of the measurement chamber (12), not even if the film is perforated.
After the film (6) has been perforated, the pressure in the measurement chamber (12) is reduced using the pump (26) to such an extent that the film (6) bulges. The film (6), thus, comes loose from the substantially rigid element (8), creating a fluid connection between the inner volume (16) of the measurement chamber (12) via the perforation (10) with the inner volume of the package (2) .
Subsequently, the valve (22) is closed. The pressure in the measurement chamber (12) will then become substantially equal to the pressure in the package (2), because fluid flows from the measurement chamber into the package or from the package into the measurement chamber. If no fluid flows, and the pressure in the measurement chamber remains substantially constant, the pressure in the measurement chamber can be determined, for example using pressure sensor 18. It is further possible to follow a variation in the pressure in the measurement chamber (12) to be able to detect a possible leak in the package (2) .
Once the measurement has been made, the pressure in the measurement chamber can be increased. Preferably, the pressure in the measurement chamber is increased quickly, for example by means of opening a valve (40), which is connected to air under atmospheric pressure, wherein the valve (40) has a much larger throughput for air than the perforation in the film (6) . If the pressure in the measurement chamber (12) is increased very quickly, the film (6) is pressed against the substantially rigid element, thereby sealing through-going perforation (10). If necessary, using the pump (26), a partial vacuum is applied to the inner volume (16) of the measurement chamber (12) at a higher pressure than the partial vacuum in the package (2) to measure (using the pressure sensor 18) whether the perforation (10) is sealed. Although the package (2) is hermetically re-sealed after the measurement, the film (6) around the blind hole (38) can be connected to the substantially rigid element fluid-tightly, for example by means of a seal seam, so that no fluid connection is created via the perforation between the inner volume of the package and an environment. The perforation can also be sealed on the outer side of the package, for example taped up, for example with airtight tape .
Fig. 4 shows a schematic representation of a third embodiment of a device for determining the pressure prevailing in at least one package. The device (1) shown in Fig. 4 substantially corresponds to the device shown in Fig. 3. The device shown in Fig. 4 is further fitted with sealing means (42) . In this example the seals (42) are designed as a seal-ring for welding the film to the substantially rigid element (8) . In this example the seal-ring is connected to the rod of the cylinder. The device (1) shown in Fig. 4 can be used to carry out the method for determining the pressure prevailing in at least one package according to what has been explained in relation to Fig. 3.
If the needle 30 is moved forwards and backwards by means of the movement device (32) for perforating the film, the seal ring is cold and the film (6) cannot yet adhere to the substantially rigid element (8). Once the measurement has been made, using the movement device (32), the seal-ring, which is now heated, presses the film (6) against the substantially rigid element. When the film (6) around the blind hole (38) has been welded fluid-tightly, the seal-ring can be removed from the film (6) using the movement device.
Subsequently, if desired, the pressure in the measurement chamber (12) can be increased to e.g. 800 mbar, for example by opening and then closing the valve (40) . It is then possible to determine, for example using the pressure sensor 18, whether the perforation in the film is actually sealed.
Finally, the pressure in the measurement chamber (12) can be increased such that the measurement chamber can be removed.
It will be appreciated that in the examples in Fig. 3 and 4 the needle 30 can also be a hollow needle which is in a fluid communication with the inner volume (16) of the measurement chamber (12) . Thus, as soon as the needle pierces the film (6) fluid can flow from the package to the measurement chamber or vice versa. It is also possible for the substantially rigid element (8) to be manufactured from a material that can be pierced by the needle 30, such as a substantially rigid rubber. In a special embodiment the hollow needle and/or the substantially rigid element (8) are dimensioned such that the hollow needle completely pierces the substantially rigid element (8), so that the hollow needle forms a fluid connection between the inner volume of the package (2) and the inner volume (16) of the measurement chamber (12) . It is, thus, not necessary for the perforation (10) to be made in the substantially rigid element (8) beforehand. It is also possible for the material of the substantially rigid element (8) to be chosen such that the perforation formed by the needle 30 closes once the needle is removed from the substantially rigid element. The Package (2) is thus substantially sealed fluid-tightly once the needle 30 is removed.
Figs. 5a and 5b show schematic representations of a particularly advantageous embodiment of a device for determining the pressure prevailing in a package. In Figs. 5a and 5b, the opening of the measurement chamber (12) is sealed with a flexible membrane (44) defining a first inner volume
(54) filled completely with an incompressible fluid (46), like water. In use, the measurement chamber (12) is sealingly abutted to the outer surface of the packaging film (6) such that the perimeter (14) of the suction device's opening rests entirely on the rigid element (8) separated therefrom by the thickness of the packaging film (6); a second, thin volume
(16) is thus defined between the membrane (44) and the packaging film (6) . Said second volume (16) is evacuated with means (52) for making vacuum, such as for example a vacuum pump. Figure 6 illustrates how, as the pressure, Pi, in said second volume (16) is reduced by actuating a vacuum pump
(52), the pressure, P2, in first volume (54) filled with an incompressible fluid initially decreases at the same rate, since the membrane (44) tends to reduce the volume (16) but is impeded to do so by the incompressible liquid (46) in volume (54) . When the pressure, Pi, in said second volume
(16) becomes smaller than the pressure, Pm, to be determined in the package (2), the packaging film (6) starts bulging, thus reducing the volume (16) and momentarily stabilizing the pressures, Pi, and, V2, in volumes (16) and (54), respectively. This process goes on until the packaging film (6) contacts the membrane (44) and the thus formed interface grows as the second volume (16) becomes smaller, until the packaging film (6) cannot be strained further. At said point in time, the pressure, V2, in the volume (54) filled with an incompressible liquid (46), equilibrates with the pressure, P1n, prevailing in the package. By measuring the pressure, P2, with pressure gauge (18) one can therefore determine the pressure, P1n, in the package.
The membrane (44) should be positioned with respect to the device's opening such as to minimize the depth of the second volume (16) formed upon application of the measuring device against the packaging film (6) . The speed and accuracy of the pressure measurement increase as the depth of volume
(16) decrease. The optimal distance of the membrane (44) to the device's opening (i.e., the depth of volume (16)) depends on the opening size and the flexibility of the packaging film (6), and the system must be designed to allow substantial contact between the membrane (44) and the packaging film (6) as the pressure, Pi, in volume (16) decreases below the pressure, P1n, in the package. Typically the membrane (44) is fixed to the measuring device at a distance from the opening thereof comprised between 0.5 and 5 mm, preferably; 0.5 and 3 mm, most preferably 0.5 and 2 mm. The measurement can be very quick, in a matter of a fraction of a second, which renders this embodiment particularly advantageous for the pressure measurement in packages produced in a large scale. The accuracy can be as fine as 0.01 mbar. This means that with a 1 min test, wherein the pressure in the volume (54) is balanced with the one in the package as described above, the vacuum pump is switched off and the pressure evolution monitored, one can determine a leak in the package leading to a 500 mbar loss of pressure in about 35 days. Alternatively, two measurements, each requiring less than a second, may be performed at different intervals, and the difference between the pressures obtained at these two intervals can be extrapolated to determine the vacuum "life" in the package. The invention is in no way limited to the examples shown in the figures. For example, the substantially rigid element (8) can abut against the inside of the package (2) free from mechanical connections. However, the substantially rigid element (8) can also be joined to the package (2), for example glued or sealed. It is important here that at least part of the film (6) is free from any mechanical connection with the substantially rigid element (8), so that the film can bulge as described above.
The substantially rigid element can be provided with a surface structure on the side adjacent to the package (2) . for example, the substantially rigid element (8) can be corrugated. While packaging the product (4) the film (6) can abut against the substantially rigid element under the influence of vacuum pressure and follow the surface structure. Thus, for example, the film that is flat prior to packing can become deformed against the substantially rigid element, for example into a corrugated membrane. The deformed film can bulge more easily if the pressure in the measurement chamber (12) is substantially equal to the pressure in the package (2) . This allows a greater sensitivity to be achieved, or a smaller substantially rigid element to be used. It should be pointed out that the Λbulging' of the film
(6) can also include the turning flat of the film (6), for example by its coming loose from the surface structure. It is also possible for the substantially rigid element to have a surface structure on the side facing away from the package. This substantially prevents the products from sliding along the substantially rigid element. This has the advantage of reducing the chance of the product in the package blocking the perforation in the substantially rigid element . In the examples the substantially rigid element substantially abuts against the package across its entire surface. It is also possible for the substantially rigid element to have a lowered section, so that the fluid in the package is present between the film and at least part of the substantially rigid element. The film can thus bulge very easily, as the film cannot remain stuck to the substantially rigid element.
In the examples the substantially rigid element is provided with a single through-going perforation (10). However, it is also possible for the substantially rigid element to have several through-going perforations. For example, the substantially rigid element can also be designed as a grid or as a plate comprising an open porosity. It is also possible for the substantially rigid element to have at least one groove in the side of the substantially rigid element adjacent to the package, to allow the fluid in the package to flow through the groove to the volume between the film and the substantially rigid element, for example if the film bulges. In a special embodiment the substantially rigid element (8) is provided with text, for example if the film (6) is substantially transparent.
It is also possible that the substantially rigid element (8) is provided with identifying marks that allow the measurement chamber, for example a transparent measurement chamber, to be placed on the substantially rigid element positioned correctly, for example centred. Identifying marks can also be applied that can be read by a measuring robot in an automated system. If opaque film is used, an identifying mark can be applied to the outer side of the package to relocate a position of the substantially rigid element.
The present invention can be applied to a broad selection of products varying in size and texture. In particular, it can be applied to any product being solid, powdery, pasty or liquid, which packing under vacuum permits the conservation, volume reduction, integrity (e.g., against counterfeit), protection against moisture, insects, oxidation, contamination, stain, pollution, etc. of said product. For example, the product may belong to any of the groups of foodstuff, consumer's goods, pharmaceutical, cosmetics, healthcare, hygiene, and industrial products.
Examples of foodstuff comprise without being restricted to drinks, powders of reconstitution for drinks, egg based, meat, fruit, vegetable, spices, food additives like dyes, binders, coagulants flour; yeast, infants' food, dietetic and organic products, cooked preparations; seafood, dairy products, frozen products, animal food, etc. Examples of consumer's goods include textile; cloths, linen, house and office equipment, documents, paper, banknotes, artwork, electronic components, and the like.
Pharmaceutical, cosmetics, healthcare, and hygiene products include inter alia medicines and treating products in the form of pastes, creams, pills, tablets, powders, liquids, syrups.
Finally, industrial products comprise cleaning products, parts for any type of equipment in the field of transportation, electricity, electronics, manufacturing, chemistry; heavy industry, agriculture, like seeds and fertilizers, packaging, like corks for wine bottles, etc. It can also be used to apply vacuum to a package containing packed goods for saving space and hence transportation and storage costs.
The applications are infinite and they can be implemented at a small, laboratory scale to large industrial sizes, passing through all the intermediate scales from domestic and office applications to small and medium companies needs. All it requires is to adapt the size and power of the pump to the size of the package. The claimed method is simple to carry out and can be applied to large series as well as to occasional uses.

Claims

1 Method for determining the pressure prevailing in a package (2) suitable for holding a vacuum and filled with a product (4), said method comprising the following steps:
(a) providing a package (2) at least partially made of a packaging film (6) containing in its interior a product (4) and a substantially rigid element (8) comprising a first and second main surfaces separated by the element's thickness and comprising at least one opening (10) fluidly connecting said first main surface to said second main surface, said substantially rigid element (8) being positioned such that said first main surface thereof substantially lies in contact with the inner surface of the packaging film (6); (b) providing a measurement chamber (12) comprising an inner volume (16) with a suction opening which perimeter (14) fits into the perimeter of the rigid element (8) ;
(c) sealingly abutting the measurement chamber (12) to the outer surface of the packaging film (6) such that the perimeter (14) of the suction device's opening rests entirely on the rigid element (8) separated therefrom by the thickness of the packaging film (6); (d) reducing the pressure in the measurement chamber (12) until the pressure in the inner volume (16) of the measurement chamber (12) is substantially the same as the one inside the package (2); (e) determining the pressure in the inner volume (16) of the measurement chamber (12).
2. Method according to claim 1, wherein the evolution of the difference in pressure between the interior of the package (2) and the inner volume (16) of the measurement chamber (12) is followed by monitoring the level of bulging of the section of packaging film (6, 6') sandwiched between the substantially rigid element (8) and the measurement chamber (12) .
3. Method according to claim 1, wherein prior to step (e) , the packaging film (6) is perforated at a location comprised within the perimeter of the measurement chamber (12) to allow flow of a fluid such as air between the interior of the package (2) and the inner volume (16) of the measurement chamber (12), thus equilibrating the pressures in the package (2) and the measurement chamber (12) .
4. Method according to claim 3, further comprising sealing the aperture (12), after determination of the pressure in the package (2), by welding or by using an adhesive, grease, patch, or combination thereof, or by sealingly joining the inner surface of the packaging film (6) to said first surface of the substantially rigid element (8),
5 Method according to claim 1, wherein the opening of the measurement chamber (12) is sealed with a flexible membrane
(44) defining a first inner volume (54) filled completely with an incompressible fluid (46), and wherein a second, thin volume (16) is defined between the membrane (44) and the packaging film (6) upon abutting the measurement chamber (12) to the outer surface of the packaging film (6); said second volume (16) is evacuated with means (52) for making vacuum until the packaging film (6) bulges and contacts the membrane
(44), and the pressure, V2, in the volume (54) filled with an incompressible liquid (46), stabilizes, the pressure, P1n, prevailing in the package (4) being determined by measuring the stabilized pressure, P2, in the volume (54) .
6. Method according to any one of the preceding claims, wherein the substantially rigid element (8) is permeable to a fluid, such as air or oil, and substantially impermeable to the product contained in the package.
7. Method according to any one of the preceding claims, wherein the at least one opening (10) of the substantially rigid element (8) consists of at least one perforation.
8. Method according to any one of the preceding claims, wherein said first main surface of the substantially rigid element (8) in contact with the packaging film (6) is structured.
9. Method according to any one of the preceding claims, wherein the substantially rigid element is substantially designed as a plate-shaped body, which perimeter forms a disc, ellipse, polygon with or without rounded corners, or any customized shape specially adapted to the geometry of the package (2) .
10. Method according to any one of the preceding claims, wherein the perimeter of the measurement chamber' s opening is provided with a circumferential endless seal (14).
11. Method according to claims 5 and 10, wherein the membrane (44) is fixed to the circumferential endless seal
(14) .
12. Method according to claim 5, wherein the measuring fluid is a liquid.
13. Method according to any one of the preceding claims, wherein the pressure in the measurement chamber is measured with a pressure sensor.
14. Method according to any one of the preceding claims, wherein the presence of leaks in the package (2) is determined by repeating the method of any of the preceding claims or by monitoring the evolution of pressure over time.
15. Method according to any one of the preceding claims, wherein the volume of the inner volume (16) of the measurement chamber (12) is much smaller than the volume of the package (2) .
16. Method according to anyone of the preceding claims, wherein the product contained in the package is solid, powdery, pasty or liquid.
17. Method according to anyone of the preceding claims, wherein the product contained in the package belongs to one of the following groups: foodstuff, consumer's goods, pharmaceutical, cosmetics, healthcare, hygiene, and industrial products.
18. Package (2) suitable for performing a method according to any one of the preceding claims wherein the package is at least partially made of packaging film (6), characterized in that a substantially rigid element (8), comprising a first and second main surfaces separated by the element's thickness and comprising at least one opening (10) fluidly connecting said first main surface to said second main surface, is positioned in the interior of the package
(2), such that the first main surface of the rigid element (8) substantially lies in contact with the inner surface of the packaging film (6) .
19. Package according to claim 18, wherein the substantially rigid element (8) is permeable to a fluid, such as air or oil, and substantially impermeable to the product contained in the package.
20. Package according to of claims 18 or 19, wherein the at least one opening (10) of the substantially rigid element (8) consists of at least one perforation.
21. Package according to any one of claims 18 to 20, wherein at least one of the first and second main surfaces of the substantially rigid element (8) is structured.
22. Package according to any one of claims 18 to 21, wherein the substantially rigid element (8) is substantially designed as a plate-shaped body, which perimeter forms a disc, ellipse, polygon with or without rounded corners, or any customized shape specially adapted to the geometry of the package (2) .
23. Package according to any one of claims 18 to 22, wherein the rigid element (8) substantially adheres to the inner surface of the packaging film (6) .
24. Kit of parts suitable for carrying out the method of anyone of claims 1 to 17, comprising:
(a) a substantially rigid element (8) comprising a first and second main surfaces separated by the element's thickness and comprising at least one opening (10) fluidly connecting said first main surface to said second main surface; and
(b) a measurement chamber (12) comprising an inner volume (16) with a suction opening which perimeter
(14) fits into the perimeter of the rigid element (8);
wherein the perimeter of the measurement chamber (12) can rest on a film laid on one of the first and second main surfaces of the rigid element (8) to define a gas tight inner volume (16) .
25. Kit of parts according to claim 24, wherein the measurement chamber (12) is provided with a piercing device
(30) suitable for creating an aperture in a packaging film.
26. Kit of parts according to claims 24 or 25, wherein the suction device is provided with sealing means suitable for sealing an aperture (12) in a film.
27. Kit of parts according to any one of claims 24 to 26, wherein the perimeter of the suction device's opening is provided with a circumferential endless seal (14) .
28. Kit of parts according to any one of claims 24 to 27, wherein the opening of the measurement chamber (12) is sealed with a flexible membrane (44) positioned near the chamber's opening and defining an inner volume (54) filled with a incompressible fluid.
29. Kit of parts according to claim 28, wherein the membrane (44) is fixed to the circumferential endless seal (14) .
30. Kit of parts according to claims 28 or 29, wherein the incompressible fluid is a liquid.
31. Use of a substantially rigid element (8) comprising a first and second main surfaces separated by the element's thickness and comprising at least one opening (10) fluidly connecting said first main surface to said second main surface, for determining the pressure prevailing in a package (2) at least partially made of a packaging film (6) .
32. Use of a substantially rigid element (8) comprising a first and second main surfaces separated by the element's thickness and comprising at least one opening (10) fluidly connecting said first main surface to said second main surface, for determining whether a package (2) at least partially made of a packaging film (6) comprises a leak.
PCT/EP2007/053906 2006-04-24 2007-04-20 Method and assembly for determining the pressure prevailing in a package WO2007122201A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
NL1031672A NL1031672C2 (en) 2006-04-24 2006-04-24 Method and assembly for determining a pressure prevailing in at least one package.
NLNL1031672 2006-04-24

Publications (1)

Publication Number Publication Date
WO2007122201A1 true WO2007122201A1 (en) 2007-11-01

Family

ID=37401215

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/EP2007/053906 WO2007122201A1 (en) 2006-04-24 2007-04-20 Method and assembly for determining the pressure prevailing in a package

Country Status (4)

Country Link
AR (1) AR060584A1 (en)
NL (1) NL1031672C2 (en)
PE (1) PE20080049A1 (en)
WO (1) WO2007122201A1 (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NL2010016C2 (en) * 2012-12-19 2014-06-23 Aartsleakandpressure B V Method and apparatus for controlling and/or determining a pressure.
EP3409600A1 (en) * 2017-06-02 2018-12-05 MULTIVAC Sepp Haggenmüller SE & Co. KG Tray sealing maschine

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE29709635U1 (en) * 1996-11-13 1998-03-26 Bosch Gmbh Robert Device for checking the tightness of hermetically sealed packaging
EP1357374A1 (en) * 2002-04-24 2003-10-29 imt robot AG Procedure for testing a vacuum package

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE29709635U1 (en) * 1996-11-13 1998-03-26 Bosch Gmbh Robert Device for checking the tightness of hermetically sealed packaging
EP1357374A1 (en) * 2002-04-24 2003-10-29 imt robot AG Procedure for testing a vacuum package

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NL2010016C2 (en) * 2012-12-19 2014-06-23 Aartsleakandpressure B V Method and apparatus for controlling and/or determining a pressure.
WO2014098594A1 (en) * 2012-12-19 2014-06-26 Oxipack B.V. Method and apparatus for controlling and/or determining a pressure
EP3409600A1 (en) * 2017-06-02 2018-12-05 MULTIVAC Sepp Haggenmüller SE & Co. KG Tray sealing maschine

Also Published As

Publication number Publication date
PE20080049A1 (en) 2008-02-23
NL1031672C2 (en) 2007-10-25
AR060584A1 (en) 2008-06-25

Similar Documents

Publication Publication Date Title
EP2054304B1 (en) Package with an element for the controlled change of the gas content inside the package
US20070266773A1 (en) Instrument and Method for Detecting Leaks in Hermetically Sealed Packaging
US3973249A (en) Apparatus for detecting leakage from container and method therefor
CN104040317A (en) Quick leak detection on dimensionally stable/slack packaging without the addition of test gas
CN204666325U (en) Air-leakage test tool
CA2930995C (en) Apparatus and method for the detection of leaks in a sealed container
WO2007122201A1 (en) Method and assembly for determining the pressure prevailing in a package
WO2007143282A2 (en) Device and method for evacuating a storage bag
US20030033857A1 (en) Apparatus and method to detect leaks in sealed packages
CN213364155U (en) Multivariable air tightness testing device
CN105841881A (en) Vacuum degree detection structure and detection method of external compound packaged five-layer coextrusion infusion bag
CN207689327U (en) Gas permeation rate tester and its leakage-proof structure
CN1195208C (en) Leakage amount detector
CN212645993U (en) Sealing performance detection device of sealing member
JP2004284677A (en) Method and device for testing leakage of package seal part
CN203337342U (en) Detection device for leakproofness of plastic bag packaging sealing
CN207580303U (en) Leak-checking apparatus and pack equipment with leak-checking apparatus
NL1032367C2 (en) Pressure prevailing determining method of packet filled with product e.g. nuts involves reducing pressure in measurement chamber until pressure in inner volume of measurement chamber is same as pressure inside package
NL2016717B1 (en) Method and system for measuring leak tightness of a sealed package
JP2922939B2 (en) Leak test method for closed synthetic resin containers
CN210347025U (en) Packaging bag sealing test device
JP2002022593A (en) Leak detection apparatus and leak detection method
CN217321308U (en) Air tightness detection device for solid probiotic powder strip bags
CN102829932A (en) Filter integrality detection device
CN107727329B (en) Method and instrument for testing one-way exhaust valve for packaging bag

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 07728364

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 07728364

Country of ref document: EP

Kind code of ref document: A1