Abstract: A valve assembly having a valve-seal on a valve member that moves between an open and a closed position within a valve support housing for controlling fluid flow, particularly for use as a shut-off valve. In many embodiments, advancing the valve member sealingly engages the valve-seal with a valve seating area of the housing to close the valve and shut-off fluid flow through the housing, while retracting the valve member moves the valve-seal away from the seating area to allow fluid flow around the valve-seal and through the valve-seating area. In many embodiments, the valve member includes a proximal handle and angled ramp that engage with a helical ramp of the housing to translate rotation of the handle into axial movement of the member between open and closed positions.