A liquid cryogen withdrawal device includes a plug (14) for insertion into the neck of a cryogen-containing dewar (10) in gas-tight relationship. A withdrawal tube (17) passes through the plug to conduct liquid from the bottom of the dewar through a sintered bronze filter to a container to be filled...http://www.google.de/patents/US5488831?utm_source=gb-gplus-sharePatent US5488831 - Liquid cryogen withdrawal device
