Fluid transfer apparatus including a body having a bore formed through at least a portion of its interior. Contained within the bore is a movable plunger that moves without changing the axial dimensions of the body. A first end of the body contains a face designed to be attached to an upstream component. A second end of the body is connected to a downstream component such as a filter, pipeline, etc. A first end of the plunger, when it is in 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 remainder of the interior of the body, the plunger and downstream components. An outer annular collar is rotatable relative to the body and causes the plunger to move axially within the bore from an open to a closed position.