The present invention relates to a process for the sterile transfer of fluids, be they liquids or gases. It uses a presterilized device comprised of a body having a bore formed through at least a portion of its interior. Contained within the bore is a movable plunger. The body has a first and a second end. The first end contains a face designed to be attached to the upstream component. The second end is connected to a downstream component such as a filter, pipeline, sample bag and the like. The plunger has corresponding first and second ends. The first end of the plunger when it the closed position is in alignment with the face of the body which combined form a steamable surface and a sterile barrier against the environment to the rest of the interior of the body, the plunger and downstream components. The device is attached to an upstream component and the face and the first end of the plunger are steam sterilized in place.