The mass flow rate of helium from a container is controlled by two disks having highly polished mating surfaces and mounted for rotation relative to one another. Each of the disks has at least one axial through passage, at least one of the disks having a through passage which is eccentric to the axis...http://www.google.de/patents/US4305261?utm_source=gb-gplus-sharePatent US4305261 - Controllable phase separator for sealing containers filled with superfluid helium
