Abstract: Molten metal is pumped from a furnace to a place where it is utilized using a gas-plunger pump having a container holding the chamber with an inlet for drawing metal from the furnace to the chamber, and with an outlet for forcing metal out of the chamber to the place of use. The inlet and outlet are disposed at the bottom of the chamber. A suction and pressure system includes a closed circuit containing a vacuum tank, a pressure tank, a vacuum pump/compressor unit connected between them, and a first valve. The closed circuit is connected to the chamber via a conduit. A control system alternately connects and disconnects the vacuum tank and pressure tank and substantially synchronously alternately opens and closes the inlet and outlet by actuation of valves associated with the inlet and outlet.

Abstract: A method and apparatus in the production of metallic castings in which metal in molten state is fed from a heated container to a mold or a smaller container via a pressure pipe, a pressure-generating means and a suction pipe. The temperature of the metal, which is present in the suction pipe, in the pressure-generating means and in the pressure pipe, is controlled by heat-generating means in order to keep the metal at a temperature corresponding to or exceeding its melting point, so that the metal is present in molten state during its passage through the pipes and the pressure-generating means.