Abstract:
A method and apparatus for testing seals of packages or containers incorporating gas permeable materials wherein the packages are placed between opposing components of a vacuum test chamber such that the seals of the packages are open to a pressure testing system. A flexible bladder backed by a foam material or pressurized fluid seal the gas permeable material afterwhich at least a partial vacuum is drawn to create pressure differential between interior sealed spaces of the packages and the exterior of the package seals. In some embodiments, flexible bladders are provided to initially seal opposite surfaces of packages having opposite gas permeable material covering layers.

Description:
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&#39;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 invention, a foam material, which is contoured to the outer contour of the package as it is initially formed, is provided along the opposite surface of the flexible bladder and is pressed against the bladder. The foam presses the bladder against the gas permeable material in such a manner as to not compress the material but to ensure that the gas permeable material is sealed by the flexible bladder and in such a manner that the seal of the package under test is not effected by the placement of the bladder in sealing relationship with respect to the gas permeable layer of the package. 
     The foam may be carried by a movable tool member of the test cavity such that the foam and bladder are applied to the package at the time the vacuum chamber is closed. 
     A pressure testing system such as that disclosed in U.S. Pat. No. 5,513,516 communicates with an evacuation area surrounding the seal between the gas permeable material and the tray of the package. The evacuation area includes an area surrounding the package such that the seal is in open communication with a channel through which gas may pass to the pressure testing system to thereby provide a determination of pressure differential or absolute pressure measurements which can be used to determine whether or not a leak exists in the seal of the package under test. 
     During a test, a source of vacuum is connected with the gas channel from the test chamber such that at least a partial vacuum may be applied in the area of the seals of the package under test to thereby create a differential pressure between the pressure within the interior of the package and the pressure surrounding the seal. Should a leak exist, gas will pass through the seal and can be detected by changes in pressure being monitored once the at least a partial vacuum has been applied. 
     From the foregoing, the tools forming the test chamber provide a seal exteriorly of the seal of the package with the area of communication to the test system being created intermediate such seals. In this manner, the exterior seals can be constructed so as to ensure that there is no gas leakage therebetween without any adverse compressive forces applied to the seal of a package under test. 
     In some embodiments, the foam material which backs the flexible bladder will extend outwardly above at least a portion of the seal of the package. In this manner, there will be less tendency of the reduced pressure within the area surrounding the seal of the package under test causing the flexible bladder to further compress the package seal. 
     In another embodiment of the invention, packages which include opposing gas permeable layers, such as flexible pouches, are tested in a test chamber having a pair of opposing flexible bladders or membranes which are each backed by a foam material contoured to match the contour of the package prior to test. In this embodiment, the edges of the package defining the seal(s) are situated between generally fixed flanged areas of the opposing tools of the test cavity. A package placed in the test chamber is retained by the closure of the tool components relative to one another with the foam layers ensuring that the opposing flexible bladders seal off the gas permeable layers of the packaging material before any vacuum is applied to the area surrounding the seals of the package under test. The method of testing incorporates the same pressure monitoring system as previously described. 
     In the preferred embodiments described, the foam material is a somewhat flexible or soft foam material, however, the resilience of the foam material may vary, being somewhat more flexible towards the center and more rigid towards the side edges of the package under test. 
     In alternative embodiments of the invention, as opposed to using the foam material for backing the flexible bladders or membranes, a positive pressure may be applied by introducing a gas, liquid or other fluid into the area behind the bladders and causing the bladders to thus conform to the outer configuration of the package under test before a vacuum or partial vacuum is applied to the areas of the seal associated with the package. In this manner, forces are applied to conform the flexible bladders to the original configuration of the outer gas permeable walls of the package under test using a fluid as opposed to a solid. 
     In a further embodiment of the invention, adjustable seals may be associated with the test apparatus. Such seals include inflatable bladders or other materials for increasing the pressure compressing the seals of the package under test. Under such conditions, it is necessary to determine a relationship between the amount of pressure applied at the area of the seal and degree of leakage being measured by the pressure testing or sensing system of the invention, as increased pressure at the seals would reduce the amount of leakage detected by the test system. 
     The apparatus and systems of the present invention may also be utilized to test the integrity of the materials which form the packages and containers being tested and particularly for testing the gas permeable materials associated with such packages. In some instances, small pin-type holes may exist in such packaging layers which openings can be detrimental to the integrity of the packages and the sterility of the contents thereof. In this respect, the flexible bladders used with the various embodiments of the invention may be provided with a contoured or roughen lower surface which engages the gas permeable material of the packages or containers during testing. Such roughened or contoured surfaces provide a plurality of vent areas by way of which gas can pass to the cavity or chamber under a vacuum test. By monitoring the pressures an immediate indication of holes in the gas permeable material may be easily detected when compared with predetermined pressures associated with known gas permeable materials. 
     It is the primary object of the present invention to provide a method and apparatus for accurately testing for leaks in seals of packaging which incorporate gas permeable layers, either in a tray type form having a gas permeable cover or in a pouch type form wherein opposing gas permeable layers are sealed at their edges to one another, to ensure that product integrity is maintained and that any material retained within the package is safe for its intended use. 
     It is also an object of the invention to provide a method and apparatus for testing packaging to ensure integrity of seals wherein the system allows for substantially continuous testing of products such that a products under test can be tested within a matter of one to three seconds without requiring any modification to the package to initiate the tests as is the case with some prior art methods and devices for integrity testing of seals. 
     It is yet another object of the invention to provide a method and apparatus for testing gas permeable flexible wall containers wherein pressure decay technology is utilized to determine leaks without requiring the injection of costly tracer gases into packaged products. 
     It is also an object of the invention to provided method and apparatus for testing gas permeable flexible wall containers wherein the integrity of the gas permeable material may also be tested to ensure that no adversely large openings or holes exist therein which could comprise the sterility of contents of the containers. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A better understanding of the invention will be had with respect to the accompanying drawings wherein: 
     FIG. 1 is a cross-sectional illustrational view showing a first embodiment of the invention in which a Tyvek™ tray is shown under test; 
     FIG. 2 is an enlarged partial cross-sectional view of a variation of the embodiment shown in FIG. 1; 
     FIG. 3 is an enlarged partial cross-sectional view similar to FIG. 2 but showing the use of fluid pressure as opposed to the use of a foam backing member in accordance with the teachings of the invention; 
     FIG. 4 is an enlarged partial cross-sectional view similar to FIG. 2 showing a variation incorporating a controllable blow-up seal; 
     FIG. 5 is a cross-sectional view of a second embodiment of the present invention showing a flexible pouch having opposing gas permeable sidewalls being tested in accordance with the teachings of the invention; 
     FIG. 6 is a modification of the embodiment of FIG. 5 shown in cross-sectional view wherein fluid pressure is used as opposed to foam for backing the flexible membranes of the invention; 
     FIG. 7 is an enlarged partial cross-sectional view of the embodiment shown in FIG. 6 showing the seal area of the pouch under test; 
     FIG. 8 is an enlarged cross-sectional view showing another variant of the embodiment of FIG. 6; 
     FIG. 9 is a differential pressure testing circuit diagram of the invention; 
     FIG. 10 is an absolute pressure testing circuit diagram of the invention. 
     FIG. 11 is a combination absolute and differential testing circuit according to the invention; 
     FIG. 12 is a partial cross sectional view of a modified bladder of the invention; and 
     FIG. 13 is a partial cross sectional view of an embodiment of the invention for testing for leaks in gas permeable cover layers of packaging being tested in accordance with the invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     With continued reference to the drawing figures, the invention is for use in testing leaks in packaging having one or more covering layers of a gas permeable material. In FIG. 1 a package  10  includes a tray  20  which is formed of a material which is non-permeable to gas contains a product “P”. The tray includes an upper outwardly directed flange  21  and is covered by a gas permeable material layer  22  which is sealed at the interface between the outer edges thereof and the flange  21  by a seal  24  which may be formed of an adhesive material, fusion bonding of the material layers, or in some other manner to form the package. The gas permeable layer  22  is provided to allow oxygen or other gas to pass therethrough to the product contained within the tray. Such containers are referred to in the industry as Tyvek™ containers. 
     To ensure the integrity of the seal  24  between the gas permeable layer  22  and the flange  21  of the package  10 , the tray  20  is placed within a conforming cavity  25  formed in a tool component  26  of a vacuum chamber  28 . Tool component  26  will be described as a bottom tool, however, in some embodiments, different orientations may be possible and be within the teachings of the invention. 
     The bottom tool  26  is opposed by an upper tool component  30  which is carried by a ram  32  associated with a control member generally shown in outline at  34  which moves the upper tool  30  relative to the lower tool. The upper tool component includes a recessed area  36  therein in which is seated a foam material  38 . The foam is mounted behind a flexible non-gas permeable membrane  35  which is secured across a lower face of the upper tool component  30 . The membrane may be, for example, a pliable rubber material. It is preferred that the foam material generally extend outwardly within the recess  36  so as to fully cover and press the membrane  35  to seal against the gas permeable layer  22  of the package  10  when the tool components are closed relative to one another to define the vacuum chamber therebetween. In this manner, the gas permeable layer  22  is sealed such that no gas can pass therethrough. The foam material is preferably a soft foam, such as a soft silicon base rubber material. However, in some embodiments, the density of the material may change with a harder foam being applied on the edges of the material than at the center portion such that the softer and more resilient foam is provided above the central area  24  of the package. 
     A front surface  39  of the foam material is generally of a configuration compatible to the configuration of the gas permeable layer  22 , which in the embodiment shown at FIG. 1 is generally planar, such that any residual slack and surface air is removed, and limited pressure is placed by the membrane  35  on the gas permeable layer  22  forcing it into the package when the vacuum chamber is closed. Thus the internal volume of the package should not change when a vacuum is applied to the cavity  25  adjacent the seal  24  of the package by way of a vacuum passageway  42  provided in the lower tool part  26 . In some embodiments, channels may be provided as grooves or raised portions for supporting the package within the cavity  25  such that the vacuum is applied directly at the interface or seal  24  between the upper gas permeable layer  22  and the flanges  21  of the tray  20 . In this manner, when a vacuum is applied, a pressure differential is created in the area of the seal between an internal space  43  within the container or package and the cavity  25  surrounding the seal  24 . 
     As shown in drawing FIG. 1, a mechanical seal such as a gasket or o-ring  44  may be provided for sealing the area between the flanges of the opposing tool components of the test cavity and which is spaced outwardly relative to the seal  24  between the gas permeable layer  22  and the tray  20  of the package under test. 
     Using the methodology of the present embodiment of the invention, once the package is placed within the cavity  25 , the upper tool component  30  is lowered such that the flexible membrane  35  initially seals the gas permeable layer  22  of the package thus preventing gas exchange to or from the internal space  43 . During this time, the upper tool  30  is sealed relative to the lower tool  26  by the gasket or o-ring  44  such that the cavity  25  communicates with the passageway  42  so that a pressure test can be performed on the seal  24 . 
     With reference to FIG. 9, during the pressure test, a vacuum or partial vacuum is applied to the cavity  25  through passageway or channel  42  and valve  11  by a vacuum pump  12  as is taught in U.S. Pat. No. 5,513,516, the contents of which are incorporated herein by reference. Once an appropriate vacuum or partial vacuum has been applied to establish a differential pressure between the interior of the internal space  43  of the package and pressure in the cavity  25 , either an absolute or differential pressure test is performed to make a determination of whether or not there is any leakage of gas through the seal  24 . 
     After a period of stabilization following the depressurization of the enclosed space or cavity  25  of the test chamber, a valve  19  is closed to initiate a predetermined timing cycle for measuring a change in pressure within the cavity  25 . The pressure in the enclosed space is measured by means of pressure transducer systems as shown in FIGS. 9 to  11 . As shown in FIG. 9, pressure is measured by use of differential pressure transducer  17  and amplifier  18 . If the measured vacuum falls below a specified level or the vacuum decreases (pressure increases) more than a predetermined amount, the package is determined to have a leak. The pressure is measured dynamically by detecting the change of pressure in the enclosed space over time. As opposed to measuring the pressure over time, an absolute pressure may be measured by connecting channel  42  to a transducer  14  and an absolute amplifier  15 , see FIG.  10 . The absolute measurement is not as accurate as the differential measurement and is principally used for the detection of large defects, whereas the differential vacuum is used to detect minor defects. 
     As shown in FIG. 11, the test system may include both the transducers and amplifiers of the dynamic and the absolute systems in fluid communication with the vacuum pump  12  and valve  11 . 
     With particular reference to FIG. 2, a slight variation of the embodiment of FIG. 1 is shown wherein the foam material  38  extends across only a portion of the seal area  24  between the upper gas permeable layer  22  and the flange  21  of the tray  20  with the tool  30  extending across the remaining portion of the seal  24 . In this embodiment, the test vacuum pressures are applied through the passageway  42 ′ to the cavity  25  adjacent to the seal  24 . In this embodiment, when the internal vacuum is applied, membrane  35  will place a greater force along the outer portion of the seal area  24 . 
     With specific reference to FIG. 3, another variation of the first embodiment of the invention is disclosed. In this embodiment, as opposed to providing a foam material  38  in backing relationship with respect to the flexible bladder  35 , positive air pressure is used in a the recessed area  36 ′ adjacent to the flexible bladder. A channel  46  is provided through the upper tool part  30  which communicates through a valve  47  with a source fluid under pressure  48 , such as a pump, so that a controlled amount of pressure may be introduced into the area  36 ′ to provide sufficient force to engage the bladder across the gas permeable layer  22  without forcing the material into the internal volume or space  43  of the tray. 
     As shown in drawing FIG. 3, the size of the recess  36 ′ may be varied and the recess may extend over the entire seal area  24  or only partially across the seal area  24  in a manner as discussed with respect to the foam material of FIG.  2 . 
     With specific reference to FIG. 4, a further modification of the first embodiment of the invention is disclosed wherein the foam material is shown as being applied to the flexible membrane  35 . However, in this embodiment, an inflatable gasket  50  is provided over the area of the package seal  24 . Positive pressure is applied through a passageway  56  connected to a valve  57  downstream of a source of pressure or pump  58 . By supplying regulated pressure to the inflatable gasket  50 , a force on the seal  24  can be regulated. The amount of force can be communicated to controls associated with the pressure testing system to thereby effectively monitor leakage of any gas from the internal portion of the tray depending upon the pressure applied at the seal  24 . 
     With particular reference to FIGS. 5-8 a second embodiment of the invention is disclosed in greater detail which is particularly designed for testing of flexible pouches  60  having oppositely oriented or opposing gas permeable material layers  61  and  62 , respectively, which are sealed at their edges as shown at  63  either by an adhesive, conductive and sonic welding or the like. In this embodiment, as the pouch is formed with two gas permeable layers, it is necessary to ensure that there is no gas passing through either gas permeable layer when a test of the seal  63  is performed by creating a vacuum or partial vacuum at an area  70  adjacent to the seal. The area  70  is connected by fluid passageway  72  to the test system of the invention. In this embodiment, the test cavity includes a vacuum chamber  75  having a lower or bottom tool part  76  and an upper tool part  77 . Tool part  76  has a cavity  78  formed therein and the upper tool part  77  has a cavity  79  formed therein. Each of the cavities  78  and  79  house generally soft foam materials, as previously described, shown at  80  and  81 , respectively, having inner surface contours  82  and  83  which match the configuration of the outer surface of the pouch when in its normal position before any testing vacuum is applied relative thereto. The purpose of the foam is to provide a sealing pressure to a pair of opposing bladders  85  and  86  made of the same material as described with respect to the embodiment of FIG.  1 . The bladders seat against and seal the gas permeable layers  62  and  61  to prevent fluid flow therethrough during the testing procedure. Further, the configuration is such as not to force the gas permeable layers  61  and  62  inwardly of an inner space  90  of the pouch. 
     Once the bladders have been sealed by movement of the upper tool part  77  relative to the lower tool part  76 , which movement also seals the tool parts with respect to the upper diaphragm  86 , as shown at  91 , the test procedure can be performed. By providing differential pressure between the interior space  90  and the space or area  70  between the seal  63  of the upper and lower layers  61  and  62  of the pouch, a determination can be made over time as to any changes in pressure following the application of the vacuum or partial vacuum in the area  70 . 
     With specific reference to FIG. 6, a variation of the embodiment of FIG. 5 is shown in which the foam backing materials  80  and  81  have been replaced by pressure chambers  100  and  101  which are positioned on opposite sides of the gas permeable layers  62  and  61 , respectively. A pair of channels  102  and  103  communicate with a valve  104  connected to a source of fluid pressure  105  such that pressurized fluid can be introduced into the chambers  100  and  101  to provide pressure to force the bladders  85  and  86  into sealed engagement with the gas permeable layers  62  and  61  of the pouch. Again, the fluid pressure is only sufficient to provide a sealing contact and not to deform the gas permeable layers  62  and  61  of the pouch. After the appropriate pressure is applied, a test can be made with respect to a leak of the seal area  63  of the pouch by initially applying a vacuum or partial vacuum in the area  70  surrounding the seal and thereafter monitoring changes in pressure within those areas. 
     With respect to FIG. 7, a slight variation of the previous embodiment is shown. In this embodiment, instead of communicating the area  70  adjacent to the seal  63  through the lower tool part, the evacuation channel  72 ′ is provided through the upper tool part. Also, as shown in this drawing figure, in some embodiments, a variation of the gasket material  49 ′ may be applied between the tool parts exteriorly of the seal area  63  between the gas permeable layers of the pouch. 
     Although not shown in the drawing figures, the seal area  70  of this embodiment of the invention may also include blow-up seals or gaskets which can be monitored to determine the amount of pressure being applied to the seal  63  which pressure is supplied to the system to compute changes in pressure caused by the application of the vacuum in the area  70  adjacent to the seal  63  by the test system of the invention. 
     With particular reference to FIGS. 1 and 12, the method and apparatus of the present invention may be utilized to test for holes or leaks in the gas permeable layer  22  of the Tyvek™ containers or packages. If holes exist or are created in the gas permeable layer, it is possible the contents of the containers can become unsterilized and, thus, it is necessary, in some instances, to ensure the integrity of the gas permeable covering materials. 
     To test for leaks in the gas permeable material, a testing apparatus such as shown in FIG. 1 is used with the exception that a modified membrane or bladder is used to seal against the gas permeable layer of the package. As shown in FIG. 12, the modified membrane  35 A includes a contoured or roughened lower surface  35 A′ which creates a plurality of small channels through which gas can flow to the cavity  25  when a package is placed under a vacuum during a test procedure. The membrane is formed of the same material as the membrane  35  disclosed with respect to the embodiment previously described with respect to FIG.  1 . If a container has been previously tested utilizing the membrane  35  disclosed with respect to the embodiment of FIG. 1, the absolute pressure which was measured may be compared with the absolute pressure determined utilizing the contoured or roughened membrane  35 A to provide an immediate indication that a leak or hole exists in the gas permeable layer  22 . Further, a pressure change for a fully functional gas permeable layer  22  can be determined and thus compared to any test results obtained utilizing the specialized membrane. 
     With particular reference to FIG. 13, another apparatus and method for determining the proper integrity of the gas permeable layers  22  of packages  10  is disclosed. In this embodiment the tool or test chamber is the same as disclosed with respect to the embodiment disclosed in FIG. 1 with the exception that there is no membrane nor foam material utilized in the cavity to seal the upper surface  22  of the container  10 . The testing chamber is thus defined by an upper tool component  30  and a lower tool component  26 . A test cavity  25  is provided within the lower tool component  26  which communicates to a testing system by way of an exhaust channel  42 . The upper tool component includes a recessed area  36 , however, no foam material is seated within the recess. 
     In the present embodiment, the package seal  24  extending along the flange  21  of the package tray  10  is sealed by an overlying gasket  110 . The interface between the tool components  30  and  26  is further sealed by use of a packing material or o-ring  112  which extends around the full perimeter of the container or tray. With the tool components closed relative to one another and a package seated within the cavity  25 , a vacuum is applied to the recess area  36  of the upper tool component  30  by way of a vent  115  connected to an appropriate vacuum pump such as the pump  12  associated with the testing systems previously described. 
     With this embodiment, the gasket  110  seals the flange area of the package and allows a vacuum to be applied through channel  115  to the recess area  36 . Any pin hole or irregular opening will cause an evacuation of air from the package at a faster rate than determined with respect to packages or containers which are properly sealed with no damaged gas permeable cover layers  22 . 
     The foregoing description of the preferred embodiment of the invention has been presented to illustrate the principles of the invention and not to limit the invention to the particular embodiment illustrated. It is intended that the scope of the invention be defined by all of the embodiments encompassed within the following claims and their equivalents.