Abstract: A simple, economical valve unit for dispensing liquids and the like includes a cylindrical bell with an inwardly directed conical surface at one end and an outwardly directed radial flange at its opposite end with a central aperture in the conical surface and an open-ended buoyancy cylinder having a conical crown terminating in a projecting shaft received in the bell so said shaft extends through the aperture, and a cap seal attached to the distal end of the shaft whereby when the cylinder moves out of said bell, the cap seal will contact the conical surface in a sealing relationship, and when the cylinder moves into the bell, its conical surface will sealingly close the central aperture. The buoyancy cylinder is longer in axial length than said bell, so its projecting end can be engaged by a cap placed on a bottle in which the unit is installed to axially force its conical crown into the central aperture to prevent leakage of the liquid contents during shipment of the bottle in which the unit is installed.