US3855531A - Method of testing the seals of food containers and containers suitable therefor - Google Patents

Method of testing the seals of food containers and containers suitable therefor Download PDF

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Publication number
US3855531A
US3855531A US26693972A US3855531A US 3855531 A US3855531 A US 3855531A US 26693972 A US26693972 A US 26693972A US 3855531 A US3855531 A US 3855531A
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Prior art keywords
container
electrode
containers
product
electrical
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J Fielibert
Rooijen A Van
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Lever Brothers Co
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Lever Brothers Co
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    • GPHYSICS
    • G01MEASURING; TESTING
    • G01MTESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING STRUCTURES OR APPARATUS NOT OTHERWISE PROVIDED FOR
    • G01M3/00Investigating fluid-tightness of structures
    • G01M3/40Investigating fluid-tightness of structures by using electric means, e.g. by observing electric discharges

Abstract

A thin-walled flexible container containing sterilised foodstuff is tested by measuring the electrical conductivity of a path from the interior of the container through the seal to the outside. A container which can be so tested non-destructively is described.

Description

United States Patent [191 Fielibert et a1.

[ Dec. 17, 1974 METHOD OF TESTING THE SEALS OF FOOD CONTAINERS AND CONTAINERS SUITABLE THEREFOR [75] Inventors: Jozef Frans Fielibert, Zevenaar;

Adrianus Van Rooijen, Didam, both of Netherlands [73] Assignee: Lever Brothers Company, New

York, NY.

221 Filed: June 28,1972

21 Appl. No.: 266,939

30 Foreign Application Priority Data July 1, 1971 Netherlands 7109071 52 US. Cl 324/65 R, 53/78, 73/52, 324/65 P 51 Int. Cl GOlr 27/02 [58] Field of Search 324/65 R, 65 P; 73/52; 53/78 Primary Examiner-Robert .1. Corcoran Attorney, Agent, or FirmLever Brothers Company [5 7] ABSTRACT A thin-walled flexible container containing sterilised foodstuff is tested by measuring the electrical conductivity of a path from the interior of. the container through the seal to the outside. A container which can be so tested non-destructively is described.

2 Claims, 3 Drawing Figures PATEF-ITED W SHEET 1 BF 2 lrIIIIIIIl/lIl/r PATENTEDBEBTYIBH sumzurg METHOD OF TESTING THE SEALS OF FOOD CONTAINERS AND CONTAINERS SUITABLE THEREFOR This invention relates to the control of packaging, particularly for foodstuffs in sealed containers, and specifically to checking the seals of such containers.

Semi-rigid and flexible containers are being used more and more for the packaging of products, particularly foodstuffs which have been preserved by sterilisation. These semi-rigid or flexible containers, manufactured from materials such as metal (e.g., aluminium) coated on one or both sides with plastic or optionally made entirely of plastic, give good protection as regards tightness with respect to the surroundings as long as no damage occurs, for example as a result of rough handling. However, a source of trouble is provided by the seals for which it is not possible to guarantee tightness in 100 percent of cases, no matter what method of sealing is used, for example heat-sealing, electric or acoustic welding, etc. It will be realised that if a sterilised food container has a leak in its seal, the contents rapidly become contaminated.

Therefore, during the packaging of foodstuffs according to the above mentioned method, random test ing of the tightness of the seals is regularly carried out by the industry during production. Not only are these random tests extremely time consuming with the methods used up to now (e.g., a biological test), but they also generally have the disadvantage that they must be carried out in a manner which is wholly destructive for the containers which have been filled with the product, closed and possibly thereafter sterilised.

A quick and non-destructive method was sought according to which all the containers, if necessary, could be subjected to an effective control of the imperviousness to leakage as they leave the production line. We have realised that measurement of electric resistance across the seal yields favourable and reproducible results. Although electrical resistance testing is known from the prior art for other purposes, eg, for rubber articles (Austrian patent specification No. 147,124), it

cannot be used for the purpose aimed at here without the necessary adjustment.

Accordingly the invention provides a sealed container containing a product and incorporating an'electrode which provides an electrically conductive path between the product and the exterior of the container, said electrode being electrically insulated in such a manner as to enable conductivity between the product and the exterior of the container to be measured when at least the seal of the container is immersed in an electrolyte.

The conductivity (or resistance) can be measured in conventional manner by measurement of the current flow produced by a constant potential between the electrolyte and electrode while the container is suitably immersed, and this provides a measure of the effectiveness of the seal.

It should be realised that the invention is only applicable to the measurement of containers containing a product which is electrically conductive. This applies to most sterilised foodstuffs.

The electrode may be incorporated in the container permanently during formation of the container or during the sealing of its lid, or may be only temporarily incorporated during the testing operation.

A particularly convenient form of the former makes use of a strip of foil, or wire which passes through the container seal, i.e., it is sandwiched between the mating sealed surfaces at the seal, from outside the container to the product inside.

Desirably the wire or strip at points outside the container should have an insulating coating to prevent risk of direct electrical contact between the wire or strip and the electrolyte, and there should be no electrical contact with the walls of the container if the latter includes a layer of metal foil.

A method according to the invention comprises incorporating an electrode in said container which provides an electrically conductive path between the product and the exterior of the container immersing the container in an electrolyte, making an electrical connection to the exterior of said electrode while maintaining electrical insulation between said electrode and the electrolyte, measuring the conductivity between said electrical connection and the electrolyte, and removing the container from said electrolyte and from the electrical connection.

In a particularly convenient form where the electrode is only temporarily incorporated in the container, said electrode is a conductive needle which is injected through a point in the walls of the container and is subsequently removed, and the method further comprises resealing thev container at said point in its walls.

A convenient apparatus for carrying out this form of the process according to the invention incorporates both a conductive needle electrode and means for provision of a drop of molten plastic to re-seal the hole formed by the needle.

This latter method is particularly suitable for containers manufactured entirely from plastic.

In certain cases however this method could also be useful for semi-rigids made of metal. It is then neces sary though that, at least during the measuring, the product cannot come into contact with the cut edge caused in the metal by the conductive probe needle, or alternatively that the needle is insulated from the metal.

The device for carrying out the method according to the invention is provided with a bath filled with electroconductive and satisfactorily moistening liquid (electrolyte) in which the containers, and at least the part of them that is to be controlled, can be partially or wholly immersed, and further with a measuring device comprising a voltage source, a micro-ammeter and two electrodes, one of which sticks into the electrolyte and one of which is intended for contact with the product present in the container to be immersed in the bath. The second electrode may simply be the wall of the bath if it is electrically conductive.

For this we preferably make use of containers provided with a conductor which is electrically insulated from the wall of the container. This can be provided in the wall previously or can be inserted right through the seal during the sealing operation.

In another embodiment the electrode intended for contact with the product consists, according to the invention, of a conductive probe needle which is provided with a driving device for limited longitudinal movement of the needle between a measuring position and a withdrawn resting position, while means are present for dosing a measured amount of liquid plastic after each measuring operation. Except for the part at and near the extremity, the conductive probe needle can be provided with an insulating coating.

Containers which have been controlled according to the methods indicated are easy to identify either because of the plugging of the control hole in their bottom wall or because of the presence of an electrode.

The invention will be further explained with reference to the drawing. In this:

FIG. 1 is a sketch showing the principle involved in carrying out a measuring on a container provided with a plate electrode;

FIG. 2 shows, on an enlarged scale, the arrangement with a container provided with a tape electrode;

FIG. 3 shows schematically an apparatus for measuring the imperviousness to leakage, more particularly intended for containers made entirely from plastic.

In the figures an electrolyte bath is indicated by 1, containers to be investigated by 2 and a product present in the containers by 3.

In FIG. 1 is represented schematically a measuring operation on a container which has previously been provided with a plate electrode which at 4 on the bottom, electrically isolated from the metal outer side of the container, can be connected to the measuring system. The latter is only very schematically illustrated in the drawing and consists of a voltage source and a ,u-ammeter connected to it in series.

In FIG. 2 a more easily realised tape or wire electrode 5 is shown which can be welded within the seal when the latter is being affected. This can be carried out with standard containers in the production line, irrespective of the kind of container. In FIG 2 a container with an outside of metal (e.g., aluminium) is shown; the tape or wire electrode can, however, also be applied to containers made entirely of plastic. The electrode carries an external insulating coating to provide electrical insulation from the electrolyte.

Finally, in FIG. 3 an apparatus is shown which is preferably intended for measuring the imperviousness to leakage of containers made entirely of plastic, e.g., polypropene. Herein a conductive probe needle 6 is carried by a driving device 7 and moved manually from a withdrawn resting position to the measuring position, as shown in the figure. In doing so, the bottom wall of the container 2 is pierced and the needle is caused to extend into the conductive product. The conductivity measurement is then made.

On the upper side of the needle, a piston 8 is attached which, when the needle is subsequently withdrawn, is forced down by the driving device 7 (a form of screw jack) and pushes in front of it a measured amount of liquid plastic, in the present case also polypropene, which is present in the reservoir 9. The plastic is kept at the right temperature by the heating spiral 10 which surrounds the reservoir 9.

The liquid plastic flows on to the bottom wall of the container, whereby the hole that has been made in the bottom is closed.

As has already been mentioned in the introduction to the description, it is possible to use the aforementioned apparatus for metallic semi-rigids but only, however, if the cut edge is sufficiently insulated electrically from the product and/or the needle.

What is claimed is:

1. A method of testing the effectiveness of the seal of a free-standing thin-walled container containing therein an electrically conductive food product said container providing an electrically insulated barrier between the food product and the exterior of the container comprising the steps of inserting an electrode in a wall of the container, the electrode being in electrical contact at one portion thereof with the food product and in electrical contact at another portion thereof with a point outside of the container while being electrically insulated from the container immersing the container in an electroltye, connecting the portion of the electrode outside of the container with a source of electrical current while maintaining electrical insulation between said electrode and the electrolyte, removing the container from the electrolyte and removing the electrode. from the wall of the container.

2. A method according to claim 1 in which said electrode is a conductive needle which is injected through a point in the walls of the container and is subsequently removed, and the method further comprises rescaling the container at said point in its walls.

Claims (2)

1. A method of testing the effectiveness of the seal of a freestanding thin-walled container containing therein an electrically conductive food product said container providing an electrically insulated barrier between the food product and the exterior of the container comprising the steps of inserting an electrode in a wall of the container, the electrode being in electrical contact at one portion thereof with the food product and in electrical contact at another portion thereof with a point outside of the container while being electrically insulated from the container immersing the container in an electroltye, connecting the portion of the electrode outside of the container with a source of electrical current while maintaining electrical insulation between said electrode and the electrolyte, removing the container from the electrolyte and removing the electrode from the wall of the container.
2. A method according to claim 1 in which said electrode is a conductive needle which is injected through a point in the walls of the container and is subsequently removed, and the method further comprises resealing the container at said point in its wAlls.
US3855531A 1971-07-01 1972-06-28 Method of testing the seals of food containers and containers suitable therefor Expired - Lifetime US3855531A (en)

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NL7109071A NL7109071A (en) 1971-07-01 1971-07-01

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BE (1) BE785743A (en)
CA (1) CA959936A (en)
DE (1) DE2231441A1 (en)
ES (1) ES404421A1 (en)
FR (1) FR2144425A5 (en)
GB (1) GB1399161A (en)
NL (1) NL7109071A (en)

Cited By (21)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4503710A (en) * 1983-06-08 1985-03-12 Conoco Inc. Crack detection by electrical resistance
US5285678A (en) * 1986-12-04 1994-02-15 Seal Integrity Systems, Inc. Container seal testing and pressurization
WO1996024036A1 (en) * 1995-01-31 1996-08-08 The Quaker Oats Company Seal integrity evaluation method
US5562024A (en) * 1993-01-22 1996-10-08 Polny, Jr.; Thaddeus J. Apparatus for electroheating food employing concentric electrodes
US5572123A (en) * 1995-06-07 1996-11-05 University Of Alaska Apparatus and method for on-line inspection of electrically conductive food products using liquid electrolyte
US5583960A (en) * 1994-06-01 1996-12-10 David Reznik Electroheating apparatus and methods
US5607613A (en) * 1993-09-23 1997-03-04 Reznik; David Electroheating of food products using low frequency current
US5741539A (en) * 1995-06-02 1998-04-21 Knipper; Aloysius J. Shelf-stable liquid egg
US5760295A (en) * 1995-07-12 1998-06-02 Joven Denki Kabushiki Kaisha Method for inspecting sealed package
US5900270A (en) * 1997-09-22 1999-05-04 Cobe Laboratories, Inc. Technique for testing and coating a microporous membrane
US5962776A (en) * 1997-05-07 1999-10-05 Lehmann; Martin Method for tightness testing of closed vessels, test chamber tester and testing system therefor
US6029421A (en) * 1995-08-18 2000-02-29 Tetra Laval Holdings & Finance S. A. Method of quality control and appropriately prepared packaging container and blank
WO2001075414A1 (en) * 2000-04-04 2001-10-11 Chubpak Australia Pty Ltd Perforation detection method
US6411110B1 (en) * 1999-08-17 2002-06-25 Micron Technology, Inc. Apparatuses and methods for determining if protective coatings on semiconductor substrate holding devices have been compromised
US20020174711A1 (en) * 2000-06-23 2002-11-28 Leonard John J. Mobile pneumatic apparatus and method for testing a container seal
US20060112758A1 (en) * 2004-11-29 2006-06-01 Yuanpei Institute Of Science And Technology Method for detecting defects in a package containing metal foil by cyclic voltammetry
US20070266773A1 (en) * 2005-01-10 2007-11-22 Mocon, Inc Instrument and Method for Detecting Leaks in Hermetically Sealed Packaging
US20080092635A1 (en) * 2005-02-02 2008-04-24 Mocon, Inc Instrument And Method For Detecting And Reporting The Size Of Leaks In Hermetically Sealed Packaging
US20080163677A1 (en) * 2005-02-14 2008-07-10 Mocon, Inc Detecting And Reporting The Location OF A Leak In Hermetically Sealed Packaging
US20100237850A1 (en) * 2009-03-19 2010-09-23 Ahmed Abdullah Salem Al-Ghamdi Device and method for testing food quality
WO2011081801A1 (en) * 2009-12-29 2011-07-07 Nestec S.A. Seal integrity evaluation device and method of use thereof

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE8632565U1 (en) * 1986-12-05 1987-04-16 Henkel, Wolfgang Eberhard, 6832 Hockenheim, De
DE68911930T2 (en) * 1988-11-07 1994-04-21 Nikka Densok Ltd An apparatus for detecting abnormal conditions of part of a device relative to the moving object.
FR2810733A1 (en) * 2000-06-23 2001-12-28 Bonduelle Sa Ets Method and equipment for testing watertightness of a container, comprises application of electric potential to conductor in contact with contents while container is immersed in conducting medium
DE102011050371A1 (en) * 2011-05-16 2012-11-22 Dbk David + Baader Gmbh Method for testing leakage of enclosure of heater for selective catalytic reduction system, involves detecting adjustable testing current after applying testing voltage to electrodes, where current is shut dependent on leakage of enclosure

Citations (5)

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Publication number Priority date Publication date Assignee Title
DE338299C (en) * 1921-08-20 Max Steffen Vakuumpruefer for preserving jars
US1843234A (en) * 1931-03-24 1932-02-02 James C Karnes Testing sealed containers and method of testing containers
US2503992A (en) * 1947-06-20 1950-04-11 Us Rubber Co Inner tube tester
CA604278A (en) * 1960-08-30 Bulpitt And Sons Limited Means for and method of testing reduced pressure in sealed metal containers
US3383863A (en) * 1966-08-03 1968-05-21 Joe R. Berry Pond, tank and pit liner and method of detecting leaks

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE338299C (en) * 1921-08-20 Max Steffen Vakuumpruefer for preserving jars
CA604278A (en) * 1960-08-30 Bulpitt And Sons Limited Means for and method of testing reduced pressure in sealed metal containers
US1843234A (en) * 1931-03-24 1932-02-02 James C Karnes Testing sealed containers and method of testing containers
US2503992A (en) * 1947-06-20 1950-04-11 Us Rubber Co Inner tube tester
US3383863A (en) * 1966-08-03 1968-05-21 Joe R. Berry Pond, tank and pit liner and method of detecting leaks

Cited By (42)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4503710A (en) * 1983-06-08 1985-03-12 Conoco Inc. Crack detection by electrical resistance
US5285678A (en) * 1986-12-04 1994-02-15 Seal Integrity Systems, Inc. Container seal testing and pressurization
US5630360A (en) * 1993-01-22 1997-05-20 Polny, Jr.; Thaddeus J. Apparatus for electroheating food employing concentric electrodes
US5771336A (en) * 1993-01-22 1998-06-23 Polny, Jr.; Thaddeus J. Electrically stable methods and apparatus for continuously electroheating food
US5562024A (en) * 1993-01-22 1996-10-08 Polny, Jr.; Thaddeus J. Apparatus for electroheating food employing concentric electrodes
US5758015A (en) * 1993-01-22 1998-05-26 Polny, Jr.; Thaddeus J. Methods and apparatus for electroheating food employing concentric electrodes
US5571550A (en) * 1993-01-22 1996-11-05 Polny, Jr.; Thaddeus J. Methods for electroheating food employing concentric electrodes
US5607613A (en) * 1993-09-23 1997-03-04 Reznik; David Electroheating of food products using low frequency current
US5609900A (en) * 1993-09-23 1997-03-11 Reznik; David Electroheating of food products using low frequency current
US5863580A (en) * 1994-06-01 1999-01-26 Reznik; David Electroheating methods
US5583960A (en) * 1994-06-01 1996-12-10 David Reznik Electroheating apparatus and methods
US5636317A (en) * 1994-06-01 1997-06-03 Reznik; David Electroheating apparatus and methods
US5768472A (en) * 1994-06-01 1998-06-16 Reznik; David Apparatus and methods for rapid electroheating and cooling
WO1996024036A1 (en) * 1995-01-31 1996-08-08 The Quaker Oats Company Seal integrity evaluation method
US5741539A (en) * 1995-06-02 1998-04-21 Knipper; Aloysius J. Shelf-stable liquid egg
US5572123A (en) * 1995-06-07 1996-11-05 University Of Alaska Apparatus and method for on-line inspection of electrically conductive food products using liquid electrolyte
WO1996041208A1 (en) * 1995-06-07 1996-12-19 Vanderbilt University Apparatus and method for on-line inspection of electrically conductive food products
US5760295A (en) * 1995-07-12 1998-06-02 Joven Denki Kabushiki Kaisha Method for inspecting sealed package
US6223898B1 (en) 1995-08-18 2001-05-01 Tetra Laval Holdings & Finance S.A. Quality control packaging container
US6029421A (en) * 1995-08-18 2000-02-29 Tetra Laval Holdings & Finance S. A. Method of quality control and appropriately prepared packaging container and blank
US5962776A (en) * 1997-05-07 1999-10-05 Lehmann; Martin Method for tightness testing of closed vessels, test chamber tester and testing system therefor
US6185987B1 (en) 1997-05-07 2001-02-13 Martin Lehmann Method for tightness testing of closed containers, test chamber, test system, and tester therefor
US5900270A (en) * 1997-09-22 1999-05-04 Cobe Laboratories, Inc. Technique for testing and coating a microporous membrane
US6411110B1 (en) * 1999-08-17 2002-06-25 Micron Technology, Inc. Apparatuses and methods for determining if protective coatings on semiconductor substrate holding devices have been compromised
US6593759B2 (en) 1999-08-17 2003-07-15 Micron Technology, Inc. Apparatuses and methods for determining if protective coatings on semiconductor substrate holding devices have been compromised
WO2001075414A1 (en) * 2000-04-04 2001-10-11 Chubpak Australia Pty Ltd Perforation detection method
US20030110833A1 (en) * 2000-04-04 2003-06-19 Jolic Karlo Ivan Perforation detection method
US20020174711A1 (en) * 2000-06-23 2002-11-28 Leonard John J. Mobile pneumatic apparatus and method for testing a container seal
US6807846B2 (en) * 2000-06-23 2004-10-26 The Quaker Oats Company Mobile pneumatic apparatus and method for testing a container seal
US20060112758A1 (en) * 2004-11-29 2006-06-01 Yuanpei Institute Of Science And Technology Method for detecting defects in a package containing metal foil by cyclic voltammetry
US7624623B2 (en) 2005-01-10 2009-12-01 Mocon, Inc. Instrument and method for detecting leaks in hermetically sealed packaging
US20070266773A1 (en) * 2005-01-10 2007-11-22 Mocon, Inc Instrument and Method for Detecting Leaks in Hermetically Sealed Packaging
US20080092635A1 (en) * 2005-02-02 2008-04-24 Mocon, Inc Instrument And Method For Detecting And Reporting The Size Of Leaks In Hermetically Sealed Packaging
US7578170B2 (en) * 2005-02-02 2009-08-25 Mocon, Inc. Instrument and method for detecting and reporting the size of leaks in hermetically sealed packaging
US7571636B2 (en) * 2005-02-14 2009-08-11 Mocon, Inc. Detecting and reporting the location of a leak in hermetically sealed packaging
US20080163677A1 (en) * 2005-02-14 2008-07-10 Mocon, Inc Detecting And Reporting The Location OF A Leak In Hermetically Sealed Packaging
US20100237850A1 (en) * 2009-03-19 2010-09-23 Ahmed Abdullah Salem Al-Ghamdi Device and method for testing food quality
CN102686993B (en) * 2009-12-29 2015-06-10 雀巢产品技术援助有限公司 Seal integrity evaluation device and method of use thereof
WO2011081801A1 (en) * 2009-12-29 2011-07-07 Nestec S.A. Seal integrity evaluation device and method of use thereof
CN102686993A (en) * 2009-12-29 2012-09-19 雀巢产品技术援助有限公司 Seal integrity evaluation device and method of use thereof
JP2013515967A (en) * 2009-12-29 2013-05-09 ネステク ソシエテ アノニム Using sealing integrity evaluation device and the device
US8973425B2 (en) 2009-12-29 2015-03-10 Nestec S.A. Seal integrity evaluation device and method of use thereof

Also Published As

Publication number Publication date Type
FR2144425A5 (en) 1973-02-09 application
CA959936A1 (en) grant
DE2231441A1 (en) 1973-01-11 application
CA959936A (en) 1974-12-24 grant
BE785743A (en) 1973-01-02 grant
NL7109071A (en) 1973-01-03 application
BE785743A1 (en) grant
ES404421A1 (en) 1976-01-01 application
GB1399161A (en) 1975-06-25 application

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