A vent valve, and a vent valve assembly, for a liquid dispensing container, employ a vent disc having small open vent holes in cooperation with an overlying thin flexible flap that covers and closes the vent holes to limit liquid pressure on the holes when the container is upright, yet require little...http://www.google.com/patents/US8016142?utm_source=gb-gplus-sharePatent US8016142 - Vent valve assemblies for baby bottles
