Abstract: The invention is a vent for use with a container, such as commercial steel pails and drums, and a method for venting containers. The vent has a cap seal with one or more semipermeable membranes covering an orifice in the cap seal. The membrane prevents the passage of at least one atmospheric component, but allows the free passage of air. When a product is filled into the container at an elevated temperature and cools, a vacuum is formed within the container. The resulting vacuum opens a vacuum release device in the vent and pulls air through a hole in the cap seal, which is protected by a micro-porous membrane. The venting of air into the container relieves the vacuum without damage to the container or the product within the container.