Measuring and testing – With fluid pressure – Leakage
Reexamination Certificate
2001-10-11
2003-02-04
Williams, Hezron (Department: 2856)
Measuring and testing
With fluid pressure
Leakage
Reexamination Certificate
active
06513366
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is directed to methods and devices for testing for seal integrity in containers and packages which include flexible or semi-flexible gas permeable materials. More specifically, the invention is directed to testing for leaks in seals of such containers by methods and devices which specifically monitor absolute and differential pressures within a vacuum chamber in which a product package or container is seated during a testing cycle.
2. Brief Description of the Related Art
There is an ever increasing need to ensure for product integrity of packaged goods including sterile medical packages, pharmaceuticals and the like to protect persons the products are used on from possible infection by contaminated products. Often, the type of testing required relates directly to the type of packaging or container in which a product is housed. Testing of products which are packaged in generally non-flexible containers, such as cans, are generally tested by procedures which do not apply to testing of products in flexible containers such as pouches or covered trays.
Over the years there have been numerous innovations made for developing methods and devices for testing the integrity of seals associated with flexible walled packages or trays having flexible closures. Testing procedures have included the use of devices for applying pressure to packages which are carried along a conveyor in which the amount of deflection of the packages, or the amount of recovery, are measured in an effort to determine whether or not leaks are present either in the packaging materials or in the seals associated therewith. Other types of leak testers incorporate vacuum sources wherein packages are placed within chambers and vacuums applied to create differential pressures between the interiors of the packages and the surrounding chambers. Pressures within the testing chambers can be monitored so as to determine if there are changes in pressure after vacuums or partial vacuums are applied to create the pressure differentials and thereby give indications of leaks.
In U.S. Patent 5,513,516 to Stauffer, a method and apparatus for testing of containers is disclosed which incorporates a vacuum chamber in which a flexible or semi-flexible package is cooperatively received. A flexible wall or membrane is provided within the testing chamber and is designed to provide a sealing surface against a flexible wall of a container. Such a device was an improvement over the prior art as the use of the flexible wall or membrane allowed package materials formed of gas permeable materials to be sealed during the testing process.
In the testing of packages which include gas permeable materials, it is important that the gas permeable materials not be allowed to communicate with a vacuum area of a testing chamber, unless pin holes in the Tyvek™ lid have to be detected. The amount of leakage through the gas permeable materials may vary depending upon the exact gas permeable material being used such that consistency of test results can not be verified or compared from one package to another due to the difference in leakage rates through the gas permeable materials when vacuums are drawn to create differential pressures between the interiors and exteriors of the packages under test. In the patent to Stauffer, the flexible wall or membrane is designed to close off the gas permeable material at the initiation of a test procedure such that the membrane is drawn into close proximity with the gas permeable material by the application of a vacuum or partial vacuum thus sealing the material from the remaining portion of the package or container under test.
The application of a vacuum in the area of a package seal results in the flexible membrane compressing the area of the seal with the amount of compression increasing depending upon the vacuum being applied. By regulating the pressure along the seal, with the level of vacuum it becomes a medium by which certain seal defects can be detected more or less, depending on the customer's test criteria.
In U.S. Patent 6,050,133 to Achter et al., a method and apparatus for detecting leaks in packages is disclosed which includes an apparatus and method for testing packages overcoming the aforementioned “claimed” shortcomings. In this patent, a temporary barrier is applied to the gas permeable portion of the sealed package with the exception of a small aperture area through which a tracer gas may be supplied through the gas permeable portion and into the interior of the package. The temporary barrier is formed of an adhesive backed material which is applied to the gas permeable material to seal the material. By measuring the concentration of tracer gas outside of the seal of a package within a test chamber, it is possible to determine whether or not a leak exists in the seal of the package or container.
Unfortunately, this type of testing apparatus and method is a very tedious and slow procedure requiring application of an adhesive material to seal the gas permeable material of the package. Not only must the adhesive layer be applied, it must also be removed after the package has been tested. This is labor intensive and time consuming. Also, the adhesive material can adversely effect printing on the package or may even result in failure of a portion of the package including the gas permeable layer or the seal layer upon the removal of the adhesive covering material from the package.
One of the essential features of any testing method and apparatus is that it must be economical to the manufacturer to use so that cost of products are not increased due to slow testing procedures. When it becomes necessary to apply adhesive coverings to packages to be tested, the amount of time required for a test is increased significantly and, therefore, such procedures are not well suited for mass commercial uses wherein continuous testing of package products must be accomplished in an expeditious manner under very high speed packaging conditions.
In view of the foregoing, there remains a need to provide an apparatus and procedures for testing packages which incorporate gas permeable materials in order to ensure that the seals associated with such packages are intact and do not contain leaks which can effect the quality of the product contained within the packages but wherein such tests can be done expeditiously so as not to adversely effect the overall economics of the packaging procedures.
SUMMARY OF THE INVENTION
The present invention is directed to a method and apparatus for leak testing of packages and containers which include at least one surface layer formed of a gas permeable material such that gas is allowed to pass into and out of an interior space of the packages. The apparatus includes a vacuum testing chamber formed by opposing tool components one of which normally would form a bottom component and the other a top component, however, different orientations may be possible and yet remain within the teachings of the invention. The two components form therebetween a testing chamber in which a package to be tested is inserted such that the edges thereof which are sealed extend outwardly of the chamber between flanges of the opposing tools.
In a first embodiment, a package such as a tray or other container having one or more product containing pockets which are sealed by one or more gas permeable materials is initially positioned within one of the opposing tools with the seals surrounding the tray extending outwardly along the flanges of the opposing tools. A flexible bladder, preferably formed of a soft silicon rubber type material, but not limited thereto, is placed in overlying relationship with respect to the gas permeable material and extends outwardly, in some embodiments, beyond seals which are provided between the flanges of the opposing tools forming the test cavity. The seals associated with the test cavity are positioned exteriorly or outwardly beyond the seals of the package under test. In a preferred embodiment of the inventio
Dowell & Dowell , P.C.
Packaging Technologies & Inspection LLC
Politzer Jay L
LandOfFree
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