Patent ID: 7841379

Claim:
A system for pumping molten metal to bottom fill a mold, comprising a) a reservoir filled with molten metal to a first depth; b) a first pump crucible submerged in said reservoir, said first pump crucible having a first check valve positioned in a passageway in a bottom wall of said first pump crucible such that said first pump crucible will fill with molten metal to a second depth equal to said first depth; c) a first riser tube extending upwardly from said first pump crucible, a first check valve in a bottom end of said riser tube to prevent downward flow of molten metal in said first riser tube; d) a horizontally extending runner interconnecting said first riser tube with a fill port in said mold; e) a second pump crucible submerged in said reservoir, said second pump crucible having a second check valve positioned in a passageway in a bottom wall of said second pump crucible such that said second pump crucible will fill with molten metal to a third depth equal to said first depth; f) a high pressure source of inert gas interconnected to said first pump crucible and to said second pump crucible by a gas delivery system including piping, a pressure regulator, two flow valves, one for each said first and said second pump crucible, and a controller to switch between said two flow valves; g) a second riser tube extending upwardly from said second pump crucible, a second check valve in a bottom end of said riser tube to prevent downward flow of molten metal in said second riser tube; whereby opening one of said flow valve permits said inert gas to force said molten metal in a respective pump crucible up said riser tube through said horizontally extending runner into said fill port and switching to said other flow valve provides continuous flow of molten metal to said horizontally extending runner.