A method for supplying inert gas into a poppet valve intermediate and an apparatus for supplying inert gas are provided that are capable of properly filling the inert gas without waste into the poppet valve intermediate of any size. After a negative pressure is achieved by suction in an internal space (Win) of a poppet valve intermediate (W) as compared to an ambient pressure (Pa) of the poppet valve intermediate (W), the inert gas is supplied into the internal space (Win) until a pressure (P) of the internal space (Win) reaches the ambient pressure (Ps) of the poppet valve intermediate (W).

A method of charging a hollow valve with metallic sodium includes providing a workpiece, as a semi-finished product for a hollow poppet valve, in which a cavity has an upward opening at a free end of a valve stem at a working position; inserting a nozzle into the opening to feed an initial inert gas into the cavity by jetting the inert gas from the nozzle; moving up the nozzle to put a holder between the workpiece and the nozzle, the holder holding a rod-like metallic sodium; and inserting the nozzle into a first end of the holder while an additional inert gas is jetted into the cavity from the nozzle to push down the rod-like metallic sodium along with the inert gas from a second end of the holder into the cavity of the workpiece.

A method and an apparatus for supplying inert gas into a poppet valve intermediate are provided that are capable of properly filling the inert gas without waste into the poppet valve intermediate of any size. After a negative pressure is achieved by suction in an internal space (Win) of a poppet valve intermediate (W) as compared to an ambient pressure (Pa) of the poppet valve intermediate (W), the inert gas is supplied into the internal space (Win) until a pressure (F) of the internal space (Win) reaches the ambient pressure (Ps) of the poppet valve intermediate (W).

A poppet valve, in particular, a hollow poppet valve, can include a valve stem; a valve cap; a valve body comprising a longitudinal axis with a stem end to which the valve stem is arranged and a cap end to which the valve cap is arranged, the valve body further comprising a cavity with a stem opening towards the stem end and a cap opening towards the cap end; wherein the stem opening of the cavity is configured to be closed by the valve stem and the cap opening of the cavity is configured to be closed by the valve cap; wherein the valve cap comprises a cap wall protruding into the cavity along an interior circumference of the valve cap; and wherein the cap wall comprises a cap wall formation.