<p>A closure device includes an outer cap and a plug engagable with a tube of the cap by sealing contact between an outside surface of a plug sidewall and an inward-facing bead of the tube. The plug may be coupled to a hollow probe of a liquid dispensing device through engagement of an inward flange of the plug in a groove of the probe. The inward flange may be angled substantially orthogonal to the plug sidewall. The plug may include one or more ribs protruding from the sidewall that act as locking interfaces with the tube bead. At least one of the ribs may have a barbed profile. An annular sealing member may contact an inside of the outer cap, and may include axial ribs.</p>
