Abstract: A valve comprising a body adapted to be associated with an opening in the wall of a fluid reservoir or flowline, to provide a flow path, from an inlet (111) at the opening, to an outlet (114), a valve seat (117) located across the flow path at the inlet (111), a valve member (116) movably supported from the body to be movable between a closed position at which it is in sealing engagement with the valve seat (117) and an open position at which it is spaced from the valve seat (117), an elongate clearing element (128) which is slidably supported from the valve member (116), said clearing member (128) having an outer end (129) which is movable towards and away from the valve member (116) between an extended position at which it extends from the valve member (116) through the valve seat (117) beyond the opening and a retracted position closely adjacent the valve (116) member, a drive means (120) to cause movement of the valve member (116) between the open and closed positions and to cause movement of the clearing