Abstract: An expendable immersion device for sensing characteristics of molten metal has a contact block and a receptacle tube. The contact block is slidingly disposed at least partially within a distal end of the receptacle tube. The expendable immersion devices includes a sensing element and a heat resistant tube. A distal end of the heat resistant tube is mounted to the sensing element. The sensing element extends partially into the interior of the heat resistant tube. A proximal end of the heat resistant tube is mounted over a distal end of the receptacle tube. A spring element is positioned over a proximal end of the contact block and abuts against the receptacle tube such that a force between the contact block and the sensing element is reduced when the heat resistant tube and sensing element are connected to the distal end of the contact block during assembly.

Abstract: A probe for measuring particulates in molten metal includes an inner metal receiving chamber, with an orifice to permit metal to flow into the chamber. A first electrode extends into the chamber and a second electrode surrounds at least a portion of the chamber. The electrodes are connected to a measurement device for measuring changes in the electrical potential produced by the passage of particulates entrained in the molten metal passing through the orifice. An outer sheath of heat resistant material surrounds the second electrode and a gas passageway extends out of the inner tube for creating a pressure differential within the chamber for facilitating the flow of molten metal through the orifice. A liquidus depressing material is in the chamber to lower the liquidus temperature of the molten metal and permit a longer time period for detecting and measuring particulates in the molten metal.