| abstract |
A storage tank defines a cryogen space for storing a cryogenic liquid. The storage tank comprises a combined fill and vent assembly, which comprises a conduit having a first end with an opening disposed within an upper part of the cryogen space, and a second end outside of the cryogen space that is connected to a receptacle, to which a re-filling nozzle can be attached. A check valve disposed in the conduit allows flow only in the direction of filling the cryogen space with cryogenic liquid from the receptacle. A by-pass line is provided around the check valve with a valve disposed in the by-pass line that is operable to open or close to control flow through the by-pass line. The method comprises attaching a re-filling nozzle to the receptacle and opening the by-pass valve to vent vapour from the cryogen space to reduce vapour pressure therein and to cool the conduit, receptacle, re-filling nozzle, and fill line. After venting the storage tank, the by-pass valve is closed, and the storage tank can be re-filled through the receptacle and conduit. |