Double foot valve for cryogenic fluid containing tanks

Claim 1

In an apparatus for pumping fluids from a storage container and permitting removal of pumping equipment in said container without loss of fluid or pressure comprising: a fluid transmitting casing extending from the top to the bottom portions of said storage container and communicating with said pumping equipment; an inlet at the bottom portion defining a passage for liquid to the pumping equipment; a fluid outlet at the upper portion of the container communicating with said transmitting casing; a foot valve extending across said inlet for sealing the passageway to said pumping equipment from the storage container when in the closed position, and permitting fluid flow from the container to the pumping equipment and through said casing when in the open position, said foot valve including means responsive to the lifting movement of the pumping equipment for closing said valve; and a sealing gland at the top of the casing accomodating movement of the pumping equipment to permit opening of the foot valve without venting the casing; the improvement which comprises: a foot valve comprising an inner poppet carrying a sealing surface and extending across said inlet for sealing engagement when in a closed position; and an outer poppet carrying a sealing surface and extending across said inlet for providing a second seal when in the closed position, said outer poppet carrying said inner poppet for independent axial movement; and means for forcing said inner poppet and outer poppet to a closed position when said pumping equipment is raised.