Apparatus for evacuating and sealing containers of perishable food or other substances includes a rigid lid for fitting onto the container and a resilientt valve which is situated over a small passage in the lid. The valve has a hollow interior region which is open at the underside of the member and...http://www.google.es/patents/US5121590?utm_source=gb-gplus-sharePatente US5121590 - Vacuum packing apparatus
