Abstract: Vent assemblies for reservoirs and other closed systems. The vent assemblies include one or more apertures in a wall of the reservoir. A closure member is retained on the external surface of the reservoir by a closure member retainer and includes a first component and a second component, the second component is relatively conformable compared to the first component. The second component is positioned between the first component and the wall of the reservoir. A sealing surface is located on either the first component or the second component, where the sealing surface closes the aperture when the closure member is in an unvented position, and the sealing surface does not close the aperture when the closure member is in a vented position.