WO1995014915A1

WO1995014915A1 - A method and an apparatus for controlling leakage from a closed container

Info

Publication number: WO1995014915A1
Application number: PCT/SE1994/001132
Authority: WO
Inventors: Bertil Ritzling; Ingvar Lindgren; Rolf Schopfer
Original assignee: Åf-Industriteknik Ab
Priority date: 1993-11-26
Filing date: 1994-11-25
Publication date: 1995-06-01
Also published as: SE9303941D0; SE9303941L; SE501693C2; AU1126395A

Abstract

The invention relates to a method and an apparatus for checking leakages in a closed container having at least one flexible wall. According to the method, in a first operation a container (1) is disposed with one of its edge surfaces or sides (6) engaging against a printed circuit board (5), which has at least two conductors (7, 8) in closely spaced relationship facing towards the container (1), a first excess pressure being generated in it for a given time interval, subsequent to which it is turned over or twisted round in a second operation, and a second excess pressure is generated in it, thus achieving, in the case of a leaking container, that the contents in the portion of the container (1) covered by the contents are pressed outwards, and in contact with the printed circuit board result in that decreased resistance can be indicated in the circuit formed by the conductors on the printed circuit board, thus indicating leakage. The inventive apparatus includes a printed circuit board (5), against which a container (1) to be tested may be placed, and which is provided with at least two conductors (7, 8), a means (12) coacting with the printed circuit board for generating an excess pressure, and at least one indicating means (11) for determining change in resistance in the conductors (7, 8) extending on the printed circuit board (5).

Description

A METHOD AND AN APPARATUS FOR CONTROLLING LEAKAGE FROM

A CLOSED CONTAINER

The present invention relates to a method and an appa- ratus for checking leakage from a closed container having at least one flexible wall. The leakage test in question is primarily intended for products in the pharmaceutical industry.

At the present time, there are no methods or equipments for performing leakage testing on the products in question, namely containers having at least one flex¬ ible wall, where good function is required for the leakage test, particularly for containers with non- conductive contents.

The object of the present invention is to provide a method and an apparatus for checking leakage from containers of the kind mentioned, whereby the testing problems outlined above have been eliminated. The distinguishing features of the invention are disclosed in the following claims.

Due to the invention there have, now been provided a method and an apparatus for checking leakage from such a container, both of which fulfil their objects in an excellent manner, while at the same time the method is readily carried out with the apparatus, the latter being simple as well as cheap in manufacture. With the aid of the invention, leakage testing is afforded a very good function, since very small leakages may be discovered. The method of achieving this in accordance with the invention is with the aid of a printed circuit board (PCB) . When the container is subjected to an excess pressure of at least two excess pressures with intermediate turning over or twisting round, any leak¬ ing material thus urged from the container is brought into contact with the PCB. The latter is provided with at least two conductors extending in mutually close relationship and can have a recess in it with a con¬ figuration completely or partially conforming to the shape of the container, the conductors being bounded by, or extending along, the outer surface of the con¬ tour formed in the PCB to suit the shape of the con¬ tainer. Since these two conductors are very close to each other, leaking material will create a conductive path between them, thus forming a closed circuit on the PCB, indicating that there is a leak, and that conse¬ quently the container should be rejected. When the containers have been subjected to the same procedure, but resistance across the conductive paths on the PCB is found to be infinite, this indicates that no mate- rial has leaked from the container to form any circuit on the PCB, the container thus being leak-free and fit for approval.

The invention will now be described in more detail below, with the aid of some preferred embodiment examples, and with reference to the accompanying draw¬ ings, where

Fig. 1 is a schematic view of an apparatus for checking leakage from a closed container,

Fig. 2 is a plan of an embodiment example of a PCB in the apparatus of Fig. 1, and which is used for leakage testing,

Fig. 3 is a schematic side view of an apparatus for turning containers upside-down in their con¬ veying direction,

Fig. 4 is a schematic, perspective view of an alter¬ native embodiment example of a PCB provided with a recess conforming to the shape of the elongate half of a container to be tested. Fig. 5 is a schematic perspective view of another embodiment of a PCB in laminated fabrication with conductive paths and insulation material alternatingly placed one on top of the other and having a similar recess to the one in

Fig. 4, and

Fig. 6 is a schematic, general view of an apparatus for checking leakage in separate containers, taken from magazines on a conveying line, with the aid of vertically oriented PCB's according to Figs. 4 or 5, but which are parted transverse their longitudinal direc¬ tion.

As seen schematically in Fig. 1, an apparatus for checking leakage from a closed container 1, in accord¬ ance with a preferred embodiment of the invention, includes a conveyor 2, on which the container or con- tainers 1 for testing are urged forwards with the aid of flights 3. These are fixed to, and urged forwards by drive means not more closely illustrated on the draw¬ ing. The container 1 is closed, and includes at least one flexible wall 4. Its contents may be electrically conductive or non-conductive, e.g. sterile or distilled water. The apparatus also includes at least one PCB 5, and using one of its sides 6, opposite to its side 4, the container to be tested may be placed in direct or indirect contact with the upper side of the PCB 5.

As will be seen more closely in Fig. 2, the PCB 5 has two conductors 7 and 8 in mutually closely spaced relationship, respectively having a large number of branches 9 and 10. The branch conductors 9 and 10 lie alternatingly at given spacing side by side in mutual parallelism, preferably such as to extend over the whole of the upper side of the PCB, and are of substan¬ tially the same length, which is such that the ends of conductors 9 and 10 do not meet respective stem conduc¬ tors 8 and 7. Conductors 7-10 consist of metal coatings deposited on the PCB. The branch conductors may also be given a pattern other than the one illustrated on the drawing, e.g. they may extend in zig-zag or wave forma¬ tion in relation to each other. In the illustrated embodiment the conductors 9 and 10 have a mutual spac- ing of about 1 mm, which may vary depending on the type of contents in the container 1 that is to be tested. From the PCB 5 the conductors 7 and 8 are connected to an indication means 11, which may be a measuring in¬ strument suitable for the purpose. The means 11 is intended to measure the resistance between the branch conductors 9 and 10, thus to determine whether there is conductive communication between any conductor pair 9, 10. This would mean that the circuit thus formed on the PCB will cause the means 11 to indicate reduced resis- tance, i.e. that there is a leak. In the case where the container to be tested has contents that are not elect¬ rically conductive per se, the PCB 5 can be previously treated with a saline solution or other soluble salts. When the solution has dried on the PCB, the salt, e.g. sodium chloride, (NaCl) remains on its surface. Accor¬ dingly, if there is a leakage of non-conductive con¬ tents from the container, e.g. sterile or distilled water, the salt in question will be dissolved and the solution caused by the leak will be electrically con- ductive. In manufacture, the PCB 5 may also be provided with material having the property of becoming electri¬ cally conductive, e.g. in contact with distilled water. The apparatus in accordance with the invention also includes at least one means 12 for generating an excess pressure in the container 1, e.g. by squeezing. The means 12 is intended to apply a given compressive force to depress one of the side walls or edge surfaces of the container 1, its side 4 in the illustrated example, to increase the internal pressure therein, but of course this pressure may be obtained in some other way. In the illustrated example, the means 12 includes a plunger 13 operating hydraulically or pneumatically in a reciprocating motion such as to generate the excess pressure. As will be seen from Fig. 1, the plunger 13 is intended to press against the upper side 4 of the container 1 at its rearward portion. In addition, the apparatus includes a means 14, with the aid of which a compressed air stream 16 is directed via at least one jet 15 to the upper side of the PCB 5, for urging any contents pressed out of the container into contact with the PCB. In order further to guarantee that any leaking contents is brought into contact with the conductors 7-10 of the PCB, the conveyor 2 and the PCB disposed thereon may slope at a given angle in the conveying direction, while the branch conductors 9 and 10 on the PCB may have a diagonal orientation on the upper side thereof.

In an alternative embodiment, not illustrated per se on the drawing, apertures in the form of slits or holes may be arranged in the PCB between conductors 9 and 10 extending over it. With the aid of sub-pressure an air stream may then be created in the apertures such as to urge any contents pressed out of the container 1 during the squeezing operation, e.g. in the form of one or more drops, into contact with the PCB and thus into contact with the branch conductors thereon.

According to another embodiment, the container may be subjected to vibration during the squeezing operation, using a vibrator (unillustrated on the drawing) , for urging any contents pressed out of the container into contact with the PCB.

The apparatus in accordance with the invention may, in an embodiment schematically illustrated in Fig. 3, include a turning device implemented as a rotatable sector drum 17 for turning the container, 180°. After the container has, in a second operation, been sub¬ jected to a first excess pressure, it is turned 180° by the drum, subsequent to which it may be subjected, in a third operation, to a second excess pressure of prefer¬ ably the same magnitude as the first. The position the container then has is either on or in contact with the first PCB 5, or when it has been taken to a second PCB. This embodiment, where the container 1 is turned 180° and subjected twice to an excess pressure, i.e. once on either side, is advantageous, when the container to be tested is not completely filled.

As applied to a first embodiment example, the method in accordance with the invention can be executed in the following manner: In a first operation the container 1 is disposed with one of its sides 6 engaging against a first PCB 5, and in a second operation the outer side 4 of it is subjected for a given time interval to an excess pressure with the aid of the plunger 13. If the container is pierced, the contents in the portion of it covered by the contents are urged to leak out, and to achieve in contact with the PCB a conductive connection between the branch conductors 9 and 10 on the PCB. The resistance of the circuit of which the conductors 9 and 10 are a part will be reduced, thus establishing the presence of leakage. In an alternative embodiment, primarily used when the container is not entirely filled, it is turned 180° after the second operation, when it is subjected to the first excess pressure, and then once again subjected to the same pressure, which may take place after transfer to a second PCB 5.

In order to indicate possible leakage from a container 1 there is used in accordance with the invention a PCB 5 including at least two conductors extending in mutu¬ ally close relationship. By subjecting a container 1 in contact with the PCB to at least one application of excess pressure, any contents pressed out of it will come into contact with the PCB and achieve a conductive connection between the conductors 9 and 10 thereon.

This connection reduces the resistance in the circuit formed by the conductors on the PCB, such as to enable determination of any leakage.

In an alternative embodiment of the PCB 5, illustrated in more detail in Fig. 4, it has a recess 18 of a configuration completely or partially conforming to the shape of the container. Here, the recess encloses substantially half of the container longitudinally. In this case the stem conductors 7 and 8 and their associ¬ ated branch conductors 9 and 10 extend over the contour of the recess in the PCB accommodating the container. These conductors may be provided by depositing an electrically conductive layer on the PCB, including the recess in it, the conductors 7 - 10 then being produced by selected portions of the deposited layer being removed, e.g. by etching. For the leakage test the container is placed in the recess 18 in this embodi¬ ment, the recess enveloping substantially half of the container longitudinally. The container is then put under pressure for providing an excess pressure inside it, which is maintained for a given time interval. Should there be any aperture in the container, its contents will be urged outwards, some of which will come into direct contact with the conductors 9 and 10 extending along the recess contour. Conductive connec- tion will then occur between the conductors, leading to reduced resistance in the circuit of which the conduc¬ tors are a part, such as to enable leakage determina¬ tion. The other side of the container may now be tested by taking it out of the recess 18 in the PCB 5 and twisting it 180° so that its former upper side is against the recess, whereon the same measures as described above are taken to determine possible leak¬ age. If there is no indication of leakage now, then the container is hermetically sealed.

In a further alternative embodiment of the PCB 5 as illustrated in Fig 5, the stem conductors 7 and 8 with their branch conductors 9 and 10 extend in closely spaced relationship in a plurality of layers one on top of the other with intermediate insulating layers 19, thus forming a laminated PCB 5. These laminae are suitably dimensioned in the direction of thickness so that the conductive laminae 7 - 10 have the same spac- ing as the spacing between horizontal conductors 7 and 8 including the branch conductors 9 and 10. The conduc¬ tive laminae 7 - 10 in the PCB extend along the recess 18 in its longitudinal direction, at right angles thereto, or both one and the other. The orientation of the conductive laminae is dependent on the shape of the container to be tested. The method of determining possible leakage is the same as that for the embodiment in Fig. 4.

Fig. 6 depicts a method of testing containers picked out for testing from magazines 24 on a conveying line. Schematically seen, leakage testing of containers 1 is performed with the aid of two mutually opposing PCB's 5' and 5", which may be moved towards and away from each other. They are respectively provided with recesses 18" and 18", which substantially conform to the shape of the portion of the container half intended to be enveloped by the respective PCB. The latter may be of the type illustrated in Figs. 4 or 5, but in this case they have been parted transversely, and in the testing procedure they have been oriented vertically. The lower half portion 21 of the container is checked here by an excess pressure being generated inside the container for a given time interval. The parting line 25 passing through the juxtaposed PCB:s 5¹ and 5" coincides with the plane of symmetry of the container 1. As will be noted from Fig. 6, the next operation in leakage testing is for the magazine 24, with container 1 placed in it, to be turned 180°. One container 1 at a time or a plurality of containers disposed adjacently with their openings downwardly directed are placed between two PCB:s 5"' and 5^M", both of which together envelope the upper portion 21 of the container half. An excess pressure is then generated inside the container 1 for a given time interval to check whether this container portion is also free from leakage. If the container is thus found to be free from leakage, it is once again placed in its magazine and when the latter is filled it is returned to the conveyor line for magazines filled with checked and approved containers, while any leaking containers are rejected. For rationalised operation, a plurality of containers placed adjacently may be tested simultaneously, if the requisite number of PCB:s is used for enveloping lower and upper portions 21, 22, respectively, of the con- tainers.

Claims

1. Method for checking leakage from a closed container having at least one flexible walls, said container being disposed for lying against at least one printed circuit board (5) , which has at least two conductors (7, 8) in mutually closely spaced relationship, an excess pressure being generated in said container (1) for urging outwards the contents thereof, should it not be hermetically sealed, on coming into contact with the printed circuit board (5) , said contents achieving a conductive connection between said conductors, said connection indicating decreased resistance in the circuit of the conductors for determining leakage, characterized in that in a first operation the con¬ tainer (1) is disposed with one of its edge surfaces or sides (6) engaging against the printed circuit board (5) , a first excess pressure being generated inside said container for a given time interval, subsequent to which it is turned over or twisted round in a second operation, and a second excess pressure is generated inside it for a given time interval, thus to achieve, in the case of a leaking container, that the contents in the portion of said container covered by said con- tents are pressed outwards.

2. Method as claimed in claim 1, characterized in that during the operation applying excess pressure to the container (1) it is subjected to a sub-pressure from at least one aperture through the printed circuit board

(5) between the conductors (7, 8) for urging, with the aid of an air stream, contents pressed out from said container into contact with said printed circuit board and its conductors (7, 8) .

3. Method as claimed in claim 1, characterized in that during the operation applying excess pressure to the container (1) it is subjected to vibration for urging contents pressed out from said container into contact with the conductors (7, 8) on the printed circuit board (5).

4. Method as claimed in claim 1, characterized in that during the operation applying excess pressure to the container (1) it is subjected to an air stream (16) directed towards the printed circuit board (5) for urging contents pressed out from said container into contact with the conductors (7, 8) on said printed circuit board.

5. Method as claimed in claim 1, characterized in that, for the case where the container contents are not electrically conductive, and before, or in connection with the leakage test, the printed circuit board (5) is provided with a material in the form of a saline solu- tion or other soluble salts, such as to cause leaking container contents to become electrically conductive on contact with said printed circuit board (5) .

6. Apparatus for checking whether there is leakage from a closed container having at least one flexible wall (4) ; said apparatus including at least one printed circuit board (5) ; a container (1) to be tested being placeable against said printed circuit board, which has at least two conductors (7, 8) in mutually closely spaced relationship; a means (12) for generating an excess pressure in coaction with said printed circuit board, intended to increase the interior pressure in said container; and at least one indicating means (11) for determining whether the resistance between said conductors on said printed circuit board changes, characterized in that said printed circuit board (5) has a recess (18) with a configuration completely or partially conforming to that of said container (1) , said conductors (7, 8) being contiguous with, or extend along the surface layer of the recess contour conform- ing to the shape of said container (1) in said printed circuit board (5) .

7. Apparatus as claimed in claim 6, characterized in that the surface layer of the recess (18) conforming to the shape of the container (1) has been treated with a saline solution or other soluble salts, such as to cause leaking container contents to become electrically conductive on contact with said surface layer, should said contents consist of such as sterile or distilled water.

8. Apparatus as claimed in claim 6, characterized in that the conductors (7, 8) including branch conductors (9, 10) extend in closely spaced relationship in a plurality of layers disposed one above the other, with intermediate insulating layers (19) such as to form a laminated printed circuit board (5) , said conductors (7, 8) and their associated separately extending branch conductors (9, 10) forming said plurality of layers extend in said printed circuit board (5) in the longi¬ tudinal direction of the recess (18) in said printed circuit board (5) , transverse thereto, or both one and the other.

9. Apparatus as claimed in claim 6 or 8, characterized in that it includes two mutually opposing printed circuit boards (5) , which may be moved towards or away from each other, each of which being provided with a recess (18) substantially conforming to the shape of half of the container (1) , seen in its longitudinal direction, and where the parting line between juxt- aposed printed circuit boards coincides with the plane of symmetry of said container (1) .

10. Apparatus as claimed in claim 9, characterized in that each of the coacting, mutually opposing printed circuit boards (5) is parted transverse its and the container's longitudinal direction to form four sepa¬ rate printed circuit boards (5', 5", 5^IM, 5""), two printed circuit boards (5¹, 5") surrounding the lower half portion (21) of the container (1) being intended to sense leakage in a first testing station (20) , and two PCB:s (5"', 5"") surrounding the upper half portion (22) of said container being intended to sense leakage in a second testing station (23) after turning said container 180°.