Pressure vacuum release hermetic valve for flexible packages

Abstract

A flexible, gussetted package having an interior for holding some particulate material product, e.g., food stuffs, under vacuum, and which includes a mouth to be opened to provide access to the contents of the package. The package is formed of a flexible material and includes a front panel, a rear panel, a pair of opposed side gussets and a pressure equalizing valve. The valve includes a displaceable slitted-aperture disk located on a valve seat and is arranged to operate in a first mode of operation wherein any gasses within the package are allowed to vent to the exterior of the package, by passing through the interface between the disk and the valve seat while the ambient atmosphere is precluded from entering into the interior of the package. The valve also operates in a second, transitory, mode wherein the slitted aperture in the disk allows a small amount of the ambient atmosphere to gain ingress into the interior so that the package's walls give a smooth appearance. The valve then enters into its third mode of operation wherein the disk engages the valve seat to isolates the interior of the package from the exterior. A layer of silicone oil is provided on the disk to facilitate operation of the valve.