| 摘要 |
<p>A flexible, gussetted package having an interior for holding some particula te material product, 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, and a pair of opposed side gussets and a pressure equalizing valve. The valve 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, while the ambient atmosphere is precluded from entering into the interior of the package. The valve also operates in a second, transitory, mo de wherein it 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 int o its third mode of operation wherein it isolates the interior of the package from the exterior.</p> |
