Airlock


 * For the episode of the Doctor Who serial Galaxy 4 entitled "Air Lock", see here.

An airlock was a device that permitted the passage of people and objects between two drastically different environments, such as between a pressurised space and a vacuum or between an underwater and dry environment. The lock usually consisted of two airtight doors in series which did not open simultaneously. This allowed the intermediate chamber to change from one environment to the other.