Patent ID: 8403000

Claim:
A system for effecting flow control and pressure management of a cryogenic liquid held in a tank, the system comprising: a first conduit communicating with the interior of the tank near the bottom of the tank; a second conduit communicating with the interior of the tank at an upper region of the tank; a third conduit communicating with the first and second conduits and extending between the first and second conduits outside of the tank; a pressure regulator disposed in the third conduit, the pressure regulator comprising a normally closed valve that opens in response to a pressure drop in the third conduit below a predetermined level; a one-way valve and an associated accumulator disposed in the third conduit between the first conduit and the pressure regulator; a fourth conduit for conducting vapor from the tank to a bulk supply, the fourth conduit being joined to the third conduit between the second conduit and the pressure regulator; a fifth conduit for introducing cryogenic liquid from a bulk supply to the tank, the fifth conduit communicating with the third conduit between the first conduit and the one-way valve; and a sixth conduit for conducting cryogenic liquid to a point of use, the sixth conduit being joined to the third conduit between the first conduit and the one-way valve, wherein the pressure regulator is configured to maintain a constant delivery pressure to the point of use as a level of cryogenic liquid in the tank falls and the pressure in the third conduit falls below a predetermined level, a valve in the pressure regulator opens, allowing cryogenic liquid in the accumulator to pass through the on-way valve and the pressure regulator and into the third conduit on the other side of the pressure regulator, where the third conduit acts as a heat exchanger in which cryogenic liquid is vaporized, causing expansion of the fluid in the third conduit which causes a pressure increase in the third conduit and in the tank.