Abstract: The present invention relates generally to an air evacuation assembly and methods of using the same, and in particular to an assembly used to evacuate air from a sealable plastic bag and to form an air tight seal, and to the methods of using the same. In a preferred embodiment, a valve assembly is provided with an inside piece that is matable with an outside piece. A plastic bag is pierced, and a gasket forms a seal with the bag when the inside piece and outside piece are threadably engaged. A check ball is contained within a spout. The ball can seal the inside of the bag, or alternatively be moved to allow air to evacuate from the bag. An external rib is provided for forming a tight engagement between the valve assembly and a pump and/or a cap.