WO2001094903A1

WO2001094903A1 - Method and apparatus for pressure testing sealed packages

Info

Publication number: WO2001094903A1
Application number: PCT/AU2001/000687
Authority: WO
Inventors: Robert Steven Stojanovic; Michael J. O'connor; John Albert Mitchell
Original assignee: Amcor Limited
Priority date: 2000-06-09
Filing date: 2001-06-08
Publication date: 2001-12-13
Also published as: AUPQ809300A0

Abstract

An apparatus and a method for pressure testing a sealed package is disclosed. The apparatus includes a test chamber 3 which is adapted to contain a medium that allows visual identification of leaks in the package. The apparatus also includes suction members in the form of vacuum pads 13 for supporting the package immersed in the medium within the test chamber. The apparatus also includes a needle 17 that can be inserted into the package and can supply a fluid to the interior of the package to generate a positive pressure within the package while the package is being held by the support means submerged in the test chamber.

Description

METHOD AND APPARATUS FOR PRESSURE TESTING SEALED PACKAGES

The present invention relates to a method and an apparatus for pressure testing sealed packages .

The present invention relates particularly, although by no means exclusively, to a method and an apparatus for pressure testing sealed packages to locate leaks or to determine parameters such as burst strength of the packages.

The pressure testing method and apparatus of the present invention can be used in relation to a wide range of packaged products, such as food, medicines, pharmaceuticals, and cosmetics, and in relation to a wide range of packaging materials and types of packages .

The pressure testing method and apparatus of the present invention can be used in relation to packaged products that are solids (including powders) and liquids.

In general terms, important requirements of packaging materials and packaging equipment are that the packages that are formed %

(a) have leak-proof seals at joins in the packages; and

(b) can resist being ruptured during normal handling at a production site, transportation to a retail outlet, handling at the retail outlet, and after purchase by a customer.

Leak testing of packaged food products at a production site is an important aspect in identifying at an early stage potential problems with packaging equipment and/or packaging materials .

The present invention is an alternative to known submerged vacuum chamber leak test systems that rely on trapped air inside a package being tested expanding and stressing the package in response to an externally applied vacuum.

The present invention is a positive pressure test system that is based on;

(a) supplying a fluid to the interior of a package being tested and generating a positive pressure within the package while the package is immersed in a medium that allows visual identification of fluid leaking from the packaging; and

(b) identifying fluid leaks from the package.

The term "positive pressure" is understood to mean that the pressure within the package is greater than in the medium in which the package is immersed.

According to the present invention there is provided an apparatus for pressure testing a sealed package, the apparatus including:

(a) a test chamber which is adapted to contain a medium that allows visual identification of leaks in the package;

(b) a means for supporting the package immersed in the medium within the test chamber; and

(c) a means for supplying a fluid to the interior of the package to generate a positive pressure within the package while the package is being held by the support means submerged in the test chamber.

The medium may be any suitable gas or liquid.

By way of example, in a situation where the fluid supplied to the interior of the package is a gas (such as air), the medium may be a liquid (such as water) which allows visual identification of leaks by virtue of gas emerging from the leak or leaks in the package forming bubbles in the liquid.

By way of further example, the medium may be a liquid or gas that undergoes a color change or other detectable change when it is contacted by fluid supplied to the interior of a package that escapes via a leak or leaks from the package and thereby identifies the location of the leak or leaks.

The fluid supplied to the interior of the package may be any suitable gas or liquid.

Preferably the fluid is air.

Preferably the medium is water when the fluid is air.

The water may include one or more additives, such as surfactants, which assist in visual identification of fluid leaking from the packaging.

Preferably the support means includes a means for lowering the package into the test chamber and for raising the package from the test chamber. - 5 -

Preferably the fluid supply means includes a piston attached to the hollow tube and a housing in which the piston can move in a forward direction towards the package so that the hollow tube can pierce the package and in a rearward direction away from the package so as to withdraw the hollow tube from the package.

Preferably the fluid supply means includes a means for applying either a positive pressure or a negative pressure to move the hollow tube in the forward or the rearward directions.

In one embodiment the pressure supply means is adapted to apply a negative pressure to move the hollow tube in the forward direction to pierce the package.

With this embodiment preferably the pressure supply means is adapted to apply a positive pressure to move the hollow tube in the rearward direction to withdraw the hollow tube from the package.

Preferably the fluid supply means is adapted to apply the positive pressure to withdraw the hollow tube from the package while continuing to supply the fluid through the hollow tube, thereby maintaining a positive pressure in the hollow tube which prevents solids (including powders) and liquids in the package entering the hollow tube as the hollow tube is withdrawn from the package.

In another, although not the only, embodiment the pressure supply means is adapted to apply a positive pressure to move the hollow tube in the forward direction to pierce the package.

With this embodiment, preferably the fluid supply The support means may support the package by clamping or any other suitable action.

Preferably the support means supports the package by applying suction to one or more sections of the package.

More preferably the support means includes at least one suction member for the package and a vacuum system for applying a sufficient negative pressure so that the suction member or members hold the package.

Preferably the support means includes a lid of the test chamber and the suction member or members are supported by the lid for rotation about a vertical axis to allow better visual observation of the package.

Preferably the fluid supply means is adapted to pierce a section of the package that is held by a suction member and thereby allow the fluid to be supplied to the interior of the package.

Preferably the fluid supply means includes a hollow tube, such as a needle, that is positioned so that it can pierce the section of the package that is held by the suction member and can extend into the interior of the package and thereby allow the fluid to be supplied via the hollow tube to the interior of the package.

With this arrangement, the negative pressure within the suction member supports the package while the hollow tube pierces the package whereby the suction member and the package form a seal that isolates the hollow tube from direct contact with the medium in the test chamber.

Preferably the fluid supply means includes a means for supplying the fluid to the interior of the package via the hollow tube. means is adapted to apply a negative pressure to move the hollow tube in the rearward direction to withdraw the hollow tube from the package.

According to the present invention there is also provided a method of pressure testing a sealed package using the above-described pressure testing apparatus, the method including the steps of:

(a) supporting the package by means of the support means;

(b) immersing the supported package in the medium in the test chamber;

(c) supplying the fluid to the interior of the package to generate the positive pressure within the package; and

(d) checking for leaks in the package.

Preferably step (a) includes supporting the package by positioning the package against the one or more than one suction member and applying a negative pressure to the member or members to thereby hold the package.

In one embodiment step (c) includes applying a negative pressure in relation to the hollow tube and moving the hollow tube in the forward direction and piercing the section of the package held by the suction member.

With this embodiment preferably the method includes applying a positive pressure in relation to the hollow tube and moving the hollow tube in the rearward direction and withdrawing the hollow tube from the package after a predetermined test period has expired. In another embodiment, step (c) includes applying a positive pressure in relation to the hollow tube and moving the hollow tube in the forward direction and piercing the section of the package held by the suction member.

With this embodiment preferably the method includes applying a negative pressure in relation to the hollow tube and moving the hollow tube in the rearward direction and withdrawing the hollow tube from the package after a predetermined test period has expired.

Preferably, step (d) includes visually inspecting the package to detect leaks .

The present invention is described further by way of example with reference to the accompanying drawing which shows one preferred embodiment of a leak test apparatus in accordance with the present invention.

The positive pressure testing apparatus includes a cylindrical test chamber 3 having a base, transparent sides, and a top opening, a lid assembly 4 that includes a lid 5 that can close the chamber 3 when a packaged product 31 is immersed in water in the chamber, and a water tank 7 that can supply water to and can receive water from the chamber 3.

In use, the water-filled chamber 3 optically magnifies the package being tested and this helps with detection and location of small leaks.

The test chamber 3 is fitted with a water sensing switch that controls sequencing of the testing process, as described in further detail below.

The lid assembly 4 includes precision guided rollers 9 that run on a vertical post 11 and enable the lid 5 to be raised and lowered. The lid 5 seals onto the test chamber 3 via "O" ring seals shown in the drawing.

The lid assembly 4 also includes a limit switch for both control and safety reasons.

The apparatus also includes a means for supporting a package being tested. The package support means includes suction members in the form of vacuum pads

13 that are mounted on a frame (not shown) that is attached to an "0" ring-sealed rotative insert 15 in the lid 5. In effect, this arrangement suspends the package to be tested from the lid 5 whereby upward and downward movement of the lid 5 raises and lowers the package from and into the water-filled chamber 3. The rotatable insert 15 enables all-round inspection of the test package.

The apparatus also includes a fluid supply means for supplying air to the interior of the package to generate a positive test pressure within the package while the package is being held by the suction members submerged in the test chamber 3.

The fluid supply means includes a small hollow needle 17 that can slide along a sealed tube 19 concentrically located in the upper vacuum pad 13 shown in the figure. The needle 17 can be pushed into and withdrawn from the package by means of a small piston 23 attached to the needle 17 and located in a cylinder 29. In use, the piston 23 is moved in the desired direction by applying either a positive pressure or a negative pressure on the rear face of the piston 23.

The fluid supply means also includes a means for generating the positive and negative pressures. The source of the positive pressure and the test pressure is an externally sourced 6 Bar air supply 45.

The negative pressure is created using the air supply 45 fed into a small vacuum ejector unit 47. When inserting or removing a test packaging the ejector 47 is manually switched on or off using a small valve attached to lid 5 of the test chamber 3. To deal with water and air leaks around the vacuum pads 13 a small vacuum tank 49 is fitted to the water storage tank 7 and includes an automatic drain that activates at the completion of each test.

The fluid supply means includes a means for changing over between positive and negative pressures. The means includes an electrically controlled solenoid 41 that is linked to a timer unit 43 that is set for a required test period.

The preferred method of operation is as follows:

(1) The water storage tank 7 is filled with water and is connected to both power and air supplies. The specified test pressure and test time are set using the pressure regulator and timer respectively.

(2) The package 31 to be tested is placed in position on the test frame and the vacuum is turned on using the valve to thereby hold the packaging in place. At this point, the needle 17 is held in a retracted position by applied negative pressure.

(3) The lid 5 and the test package 31 are lowered into the test chamber 3 (from this point on the test is automatic and the operator looks for the location of leaks indicated by the bubble trail) .

(4) On completion of the test the lid 5 may be opened and the test package 31 replaced or the test may be re-initiated by pressing a retest switch 51.

The automatic section of the test preferably occurs as follows:

(1) The lid switch supplies power to a pump 55 which pumps water from the water storage tank 7 and fills the test chamber 3.

(2) When the water reaches the probe in the lid 5 it causes (i) a water level relay 57 to close thereby to stop supply of water to the tank 3 and (ii) the air/vacuum solenoid 41 to replace the negative pressure behind the needle piston 23 with the specified postive test pressure. This causes the needle 17 to penetrate the package and to inflate the package to the test pressure. Simultaneously, the timer is initiated and takes over powering the pump via the latching relay and 240 volt relay.

(3) At the end of the timing cycle the water drains from the test chamber 3. As soon as the probe is uncovered the air/vacuum solenoid 41 changes to vacuum and the needle 17 is withdrawn from the package, thereby concluding the test.

The above described test apparatus has a number of advantages over known test systems . By way of example, - li the test apparatus is relatively inexpensive to manufacture and operate and is readily portable and therefore can be used at a range of locations at a production site.

Many modifications may be made to the preferred embodiment described above without departing from the spirit and scope of the present invention.

By way of example whilst the preferred embodiment is described in the context of detecting leaks in a package product, the present invention also extends to evaluating other parameters, such as burst strength, of a packaged product .

Furthermore, whilst the preferred embodiment described above operates using an applied positive pressure on the rear face of piston 23 to insert the needle 17 into the package and an applied negative pressure on the rear face of piston 23 to withdraw the needle after a predetermined test period has expired, the present invention is not so limited and extends to other options. One such other option is to use an applied negative pressure on the forward face of piston 23 (or any other suitable surface) to insert the needle 17 into the package and an applied positive pressure to the forward side of piston 23 (or any other suitable surface) to withdraw the needle 17. With this option, it is preferable that airflow through the needle 17 be maintained while the needle 17 is being withdrawn from the package to ensure that there is no backflow of solids and liquids in the package into the needle that could block the needle or otherwise affect adversely the air supply to the needle.

Furthermore, whilst the preferred embodiment described above operates by lowering the lid 5 so that the suspended package 31 is immersed in the test chamber 31, the present invention is not so limited and extends to an alternative arrangement in which the lid 5 and the suspended package 31 are in a fixed position and the water- filled chamber is raised to immerse the package 31.

Furthermore, whilst the preferred embodiment described above is arranged so that the hollow needle 17 is horizontally disposed, the present invention is not so limited and extends to other arrangements. One such other arrangement includes locating the needle 17 vertically and moving the needle upwardly and downwardly in a vertical direction.

Claims

CLAIMS :

1. An apparatus for pressure testing a sealed package, the apparatus including:

(σ) a means for supplying a fluid to the interior of the package to generate a positive pressure within the package while the package is being held by the support means submerged in the test chamber.

2. The apparatus defined in claim 1 wherein the fluid supplied to the interior of the package is a gas

(such as air) and the medium is a liquid (such as water) which allows visual identification of leaks by virtue of gas emerging from the leak or leaks in the package forming bubbles in the liquid.

3. The apparatus defined in claim 1 or claim 2 wherein the medium is a liquid or gas that undergoes a colour change or other detectable change when it is contacted by fluid supplied to the interior of a package that escapes via a leak or leaks from the package and thereby identifies the location of the leak or leaks .

4. The apparatus defined in any one of the preceding claims wherein the fluid is air.

5. The apparatus defined in claim 4 wherein the medium is water when the fluid is air.

6. The apparatus defined in any one of the preceding claims wherein the support means includes a means for lowering the package into the test chamber and for raising the package from the test chamber.

7. The apparatus defined in claim 6 wherein the support means supports the package by applying suction to one or more sections of the package.

8. The apparatus defined in claim 7 wherein the support means includes at least one suction member for the package and a vacuum system for applying a sufficient negative pressure so that the suction member or members hold the package.

9. The apparatus defined in claim 8 wherein the support means includes a lid of the test chamber and the suction member or members are supported by the lid for rotation about a vertical axis to allow better visual observation of the package.

10. The apparatus defined in claim 8 or claim 9 wherein the fluid supply means is adapted to pierce a section of the package that is held by a suction member and thereby allow the fluid to be supplied to the interior of the package.

11. The apparatus defined in any one of claims 8 to 10 wherein the fluid supply means includes a hollow tube, such as a needle, that is positioned so that it can pierce the section of the package that is held by the suction member and can extend into the interior of the package and thereby allow the fluid to be supplied via the hollow tube to the interior of the package.

12. The apparatus defined in claim 11 wherein the fluid supply means includes a means for supplying the fluid to the interior of the package via the hollow tube.

13. The apparatus defined in claim 11 or claim 12 wherein the hollow tube is movable in a forward direction towards the package or a rearward direction away from the package.

14. The apparatus defined in any one of claims 11 to 13 wherein the fluid supply means includes a piston attached to the hollow tube and a housing in which the piston can move in a forward direction towards the package so that the hollow tube can pierce the package and in a rearward direction away from the package so as to withdraw the hollow tube from the package.

15. The apparatus defined in any one of claims 11 to 14 wherein the fluid supply means includes a means for applying either a positive pressure or a negative pressure to move the hollow tube in the forward or the rearward directions.

16. The apparatus defined in claim 15 wherein the pressure supply means is adapted to apply a negative pressure to move the hollow tube in the forward direction to pierce the package.

17. The apparatus defined in claim 16 wherein the pressure supply means is adapted to apply a positive pressure to move the hollow tube in the rearward direction to withdraw the hollow tube from the package.

18. The apparatus defined in claim 17 wherein the fluid supply means is adapted to apply the positive pressure to withdraw the hollow tube from the package while continuing to supply the fluid through the hollow tube, thereby maintaining a positive pressure in the hollow tube which prevents solids (including powders) and liquids in the package entering the hollow tube as the hollow tube is withdrawn from the package.

19. The apparatus defined in claim 15 wherein the pressure supply means is adapted to apply a positive pressure to move the hollow tube in the forward direction to pierce the package.

20. The apparatus defined in claim 19 wherein the fluid supply means is adapted to apply a negative pressure to move the hollow tube in the rearward direction to withdraw the hollow tube from the package.

21. A method of pressure testing a sealed package using the pressure testing apparatus defined in any one of the preceding claims, the method including the steps of :

(b) supporting the package by means of the support means;

(b) immersing the supported package in the medium in the test chamber;

(d) checking for leaks in the package.

22. The method defined in claim 21 wherein step (a) includes supporting the package by positioning the package against the one or more than one suction member and applying a negative pressure to the member or members to thereby hold the package.

23. The method defined in claim 21 or claim 22 wherein step (c) includes applying a negative pressure in relation to the hollow tube and moving the hollow tube in the forward direction and piercing the section of the package held by the suction member.

24. The method defined in claim 23 includes applying a positive pressure in relation to the hollow tube and moving the hollow tube in the rearward direction and withdrawing the hollow tube from the package after a predetermined test period has expired.

25. The method defined in claim 21 or claim 22 wherein step (c) includes applying a positive pressure in relation to the hollow tube and moving the hollow tube in the forward direction and piercing the section of the package held by the suction member.

26. The method defined in claim 25 includes applying a negative pressure in relation to the hollow tube and moving the hollow tube in the rearward direction and withdrawing the hollow tube from the package after a predetermined test period has expired.