US 3432087 A
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Description (OCR text may contain errors)
March 11, 1969 COSTELLO 3,432,087
' PACKAGE VALVE Filed Aug. 1'7, 1967 Fig. 2
Pg. 3 Fig. 5 F7 15 Fig. 7
Alfred P. Costello 2 v tor y Age It United States Patent O 39,060/ 66 US. Cl. 229-625 Int. Cl. B65d 31/14, 17/24, 5/70 6 Claims ABSTRACT OF THE DISCLOSURE A package valve adapted for use with evacuated packaged food products. A seal of pressure sensitive tape secured over a weakened portion of the package, adapted for the seal to lift when pressure within the package rises sufiiciently to rupture the weakened portion.
BACKGROUND OF THE INVENTION The invention relates to pressure relief valves of a type known as a package valve. It is particularly but not exclusively adapted for use in food packaging.
As is well known, precooked or partially cooked food is often packaged in a plastic bag which, commonly, is evacuated and sealed. Foods so packaged may be prepared by boiling and, notwithstanding the package may have been evacuated, pressure may build up during boiling. Also, from time to time gasses may be generated Within the package, perhaps during storage, or the seal may be such that, after storage for a time, some air may have leaked into the container.
Pressure may thus accumulate whether or not the package is exposed to heat-by boiling or otherwise-and any initial pressure build-up will increase with heating. It will be understood by those skilled in the art that, where a package is evacuated, the vacuum is not high--nor is there particular need that it should be. Thus, pressure build-up can and does occur, and may be sufficicnt to fracture the bag.
If pressure build-up occurs before cooking, it is clear that there may be danger of the food becoming contaminated. When the pressure occurs during cooking, while there will be no contamination caused by the pressure build-up during heating, bursting of the bag-for instance whilst boiling-is undesirable since, for example in the case of packaged fish, attainment of particular advantages of packaged cooking technique, namely the freedom from odor and the easewith which a container used for preparing the food maybe cleaned thereafter, is incomplete.
In certain procedures such packaged food is prepared for consumption by high frequency electronic means, and it is found that there may be pressure build-up when this method is used. While a high frequency cooking means are not as yet ordinarily found in household stoves, there are domestic high frequency stoves already available on the market, notwithstanding that at this time such means are commonly found only in commercial establishments.
SUMMARY OF THE INVENTION The difliculties and disadvantages above may be materially reduced by providing a suitable valve means of the package. As packaging costs are passed to the consumer to be commercially successful for the present purpose a valve must, not only be acceptable functionally, but also must be of such construction that it does not add mate rially to the cost to the consumer.
While valves which meet the functional and mechanical requirement are available, the valve of my invention is 3,432,087 Patented Mar. 11, 1969 distinguished from the prior art as known to me both by its structure and by its low costthus to meet both requirements above.
Basically, my invention is a valve structure for the above described purposes, the structure having in combination; a weakend portion of a wall of the package, and a flexible sealing element having a side coated with pressure sensitive adhesive placed in adhesive engagement with an outer surface of the package over, and extending beyond, the periphery of the weakened portion. The weakened portion may, for instance, be attained by a scored or perforated outline defining the periphery, or a part of the periphery. The sealing element, usually pressure sensitive tape, prevents leakage and fracture up to a particular pressure. When, from any cause, a difference in pressure between the inside and the outside of the package exceed the particular value, the weakened periphcry will rupture thus to lift the tape, so providing escape of the internal gasses. The magnitude of pressure required to cause this to happen depends upon factors including the depth of the scoring or, in the case of perforations, the spacing between perforations, and the excess of the area of the pressure sensitive tape over the area of the outline. It is thus seen that it is a matter of design to provide a substantial range of pressure difference at which the valve will open so to permit escape of the internal gasses. It is also to be noted that, in some circumstances, when the internal pressure is relieved the pressure sensitive tape may automatically reseal the opening. Where the package is being boiled, self rescaling might occurwhile such rescaling may be incomplete, it will ordinarily occur quickly and be sufficient to prevent much water from entering the package, and to confine the food within the package.
In other environments and for other purposes, the pressure sensitive adhesive seal can be placed on an inner surface of the container so that, for instance in pressure preparation of a product, fluid is admitted to the interior of a package upon a particular pressure being reached.
DESCRIPTION OF THE DRAWINGS FIGURE 1 shows a fragmented package having a valve according to the invention,
FIGURE 2 is a section on 2-2 of FIGURE 1, thickness of the wall and of the seal being exaggerated for clarity of illustration,
FIGURE 3 is a fragmented detail of a side wall of the package, showing a weakened portion,
FIGURE 4 is a section on line 4-4 of FIGURE 1, thickness being exaggerated as in FIGURE 2,
FIGURE 5 shows an alternative form of weakened portion with perforations extending only partially around the periphery,
FIGURE 6 shows a weakened portion defined by a peripheral score,
FIGURE 7 shows a score extending only partially around the periphery,
FIGURE 8 shows a circular embodiment of the flexible seal,
FIGURE 9 shows a generally rectangular embodiment of the seal.
The drawings, and the description following relating thereto, are given by Way of exampleit is to be understood that the invention can be expressed in structure other than that of the particular examples described and illustrated.
DESCRIPTION OF PREPARED EMBODIMENTS Description of FIGURES I, 2, 3
The numeral 10 indicates generally a package of the subject kind. The package is commonly a sealed evacuated envelope of transparent plastic material having a side wall 11. A valve according to the invention is indicated generally by the numeral 12, the valve having a flexible sealing element 13, suitably pressure sensitive adhesive tape of a known kind, secured adhesive side down in engagement with the package wall 11, and disposed generally centrally over a weakened portion 14, shown in broken outline in FIGURE 1. The weakened portion 14 is generally circular, having a periphery defined by a plurality of closely spaced perforations 15. The flexible pressure sensitive seal 13 is also generally circular having a diameter larger than that of the weakened portion 14, and can be provided with a tab 16.
OPERATION, WITH PARTICULAR REFERENCE TO FIGURE 4- When for instance the package is immersed in boiling water, pressure against the wall 11 from the water is in a direction indicated by an arrow 17. Pressure in the interior of the package is indicated by an arrow 18, originally that pressure was below atmospheric but, as previously explained, through leakage or other causes it might be above or below atmospheric upon immersion. Should the pressure 18 rise to a value higher than the pressure 17 by an amount suflicient to cause the weakened portion to rupture, and thus to lift an end 19 of the seal opposite the tab 16, conditions will be as shown in FIGURE 4. The weakened portion has ruptured at a space 15.1 between adjacent spaced perforations 15, leaving a ruptured edge 15.2 of the weakened portion urged away from the package side wall 11 as shown, so that the pressure 18 is relieved escaping through the ruptured weakened area until inner and outer pressures are equalized. It is to be noted that the tab 16 acts as a. hinge, and will remain secured to the wall 11 after rupture and lifting.
When the pressures 17 and 18 are equalized the flexible seal could hang free, and if desired resealing can be effected when the package is withdrawn by pressing the seal against the wall 11 so that the adhesive side 21 of the seal is again secured. Resealing is facilitated when a tab 16 is provided. In some circumstances, rescaling or partial resealing could be automatic.
ALTERNATIVE EMBODIMENTS Weakened portion FIGURES 5, 6, 7 show alternative weakened portion structures.
In FIGURE 5, a weakened portion designated 14.5 is defined by a plurality of closely spaced perforations 15, the perforations however extending only partially around the periphery of the weakened portion so as to leave an unweakened peripheral part as seen at 22. In FIGURE 6, a weakened portion 146 is defined by a score 23. In FIG- URE 7, a weakened area 14.7 is defined by a peripheral score 24 extending only partialy around the periphery so as to leave an unweakened portion designated 25. Reseal ing is facilitated when unweakened portions, as 22 and 25, are provided.
Seal shape The pressure sensitive flexible seal may be circular, that is to say without the hinge tab 16 (FIGURE 1) which circular form is illustrated in FIGURE 8, or it may be rectangular as seen in FIGURE 7 designated 27, the rectangular flexible seal can also be provided with a tab portion indicated in broken outline by the numeral 28. Irregular shape, not shown, may also be used.
The amount by which the pressure 18 must exceed the pressure 17 before rupture occurs depends upon the relative areas of the seal 15 and the weakened portion 14, upon the spacing of the perforations 15, upon the material of the package wall, and upon other design factors. Thus, a particular pressure difference best suited to the use to which the package valve is to be put is a matter of design, and therefore is not herein described.
The foregoing descriptions have been given by way of example, and, while the release valve construction of my invention is particularly adapted for use in food packaging, the invention is not confined thereto. It can, for instance, be used in other circumstances where either self sealing or a manually rescaling valve is required, and indeed for many purposes for which a safety valve of a cheap and simple construction might be required.
The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:
1. A valve structure for a generally fluid tight package having a wall; in combination (a) a peripherally weakened portion of the wall,
(b) a flexible sealing element larger than the weakened portion aforesaid and having an inner side coated with pressure sensitive adhesive, the inner side being in adhesive engagement with a surface of the wall over and extending beyond the peripherally weakened portion,
the valve being constructed and arranged so that when fluid pressure on a side of the wall remote from the sealing element exceeds fluid pressure on the sealing element by a determinate amount, the peripherally weakened portion will rupture so disengaging the inner side of the sealing element and permitting passage of fluid through the valve.
2. Structure as defined in claim 1, the weakened portion being defined by closely spaced perforations.
3. Structure as defined in claim 1, the weakened portion being a peripheral score.
4. Structure as defined in claim 1, the flexible sealing elements having a hinge tab.
5. Structure as defined in claim 4, the weakened portion being defined by closely spaced perforations.
6. Structure as defined in claim 4, the weakened portion being a peripheral score.
References Cited UNITED STATES PATENTS 670,794 3/1901 Lott. 3,175,752 3/1965 "Stabenow 229-66 X 3,243,075 3/1966 Reinke 220-44 DAVID M. BOCKENEK, Primary Examiner.
U .5. Cl. X.R.