Probe for the determination of gas concentration in molten metal

In apparatus for the determination of gas concentration in a molten metal, the apparatus including:

• an immersion probe for immersion in the molten metal comprising a probe body having a gas inlet to its interior and a gas outlet therefrom, the gas inlet and outlet being spaced from one another so that a carrier gas passing from the inlet to the outlet traverses a substantial portion of the probe body interior for entrainment of gas diffusing to the interior of the body from the ambient molten metal;
• carrier gas supply means;
• a gas recirculation pump for the carrier gas and any gas diffused from the molten metal and entrained therein;
• a gas concentration determining means adapted to determine the proportion of the gas diffused from the metal and present in a mixture thereof with the carrier gas;
• and
• conduit means connecting the carrier gas supply means, the probe gas inlet, the probe gas outlet, the gas recirculating pump and the gas concentration determining means in a closed circuit for circulating the carrier gas through the probe body to entrain therein gas that has diffused into the probe body from the molten metal;
• the provision of an immersion probe consisting of a block of gas-permeable, liquid metal impervious material of sufficient heat-resistance to withstand immersion in the molten metal, the material of the probe body having a porosity of from about 5% to about 80%, a permeability of from about 2 to about 2,000 Darcies, and a pore size from about 0.5 micrometers to about 2,000 micrometers.