Abstract: A tap has a hollow body (6) having an interior threaded portion (18) and (9). A manually turnable spindle (7) having an exterior threaded portion (19) is threadably engaged with the interior treaded portion (18) to advance and retract to spindle (7) relative to the tap body (6) to respectively close and open the tap. A seal (28) seals the spindle (7) relative to the hollow body (6). A locking mechanism including mutual abutent portions (27, 13) on the body (16) and spindle (7) to limit the retraction of the spindle (7). The relative lengths of the threaded portions (18, 19) and the relative locations of the mutual abutment portions (27, 13) are selected so that continued turning of the spindle (7) in the retraction direction disengages the threaded engagement prior to abutment of the mutual abutment portions (27, 13).