Storage tank for a cryogenic liquid and method of re-filling same

A storage tank for a cryogenic liquid, said storage tank comprising:

• an inner vessel defining a cryogen space within which said cryogenic liquid can be stored;
• an outer shell surrounding said inner vessel;
• a support structure between said inner vessel and said outer shell for holding said inner vessel spaced apart from said outer shell, whereby an insulating space is defined between said inner vessel and said outer shell;
• a combined fill and vent assembly comprising:
• a conduit having a first end with at least one opening disposed within an upper part of said cryogen space, and a second end outside of said outer shell that is connected to a receptacle, to which a re-filling nozzle can be attached to supply said cryogenic liquid to said cryogen space through said conduit;
• a check valve disposed in said conduit, said check valve allowing flow only in the direction of filling said cryogen space with cryogenic liquid from said receptacle;
• and
• a by-pass line with one end communicating with said conduit between said check valve and said cryogen space, and a second end communicating with said conduit between said check valve and said receptacle, and a by-pass valve disposed in said bypass line and operable to an open position wherein fluid is allowed to flow through said by-pass line and a closed position wherein fluid is blocked from flowing through said bypass line.