High temperature pressure transducer system

Abstract

A high temperature pressure transducer for measuring the total pressure adjacent the exit orifice of a crucible containing molten metal used in a continuous casting operation is disclosed. The pressure sensed includes a pressure head of the molten metal as well as the gas gauge pressure in the crucible above the metal. The transducer includes a sensor rod assembly having an immersible sensor rod fabricated of fused quartz and having a sensing surface, a sensor rod extension, an intermediate shaft, and a load cell connected to the intermediate shaft. A bellows provides a gas tight seal for the internal gas pressure in the crucible. The bellows is characterized by folds projecting inwardly and outwardly and providing equal volume in the two directions. By having a constant volume, it follows that the surface area of the folds in the two directions is the same so that any pressure changes along the bellows cancels out and does not adversely affect the reading at the load cell thereby assuring an accurate total pressure reading. In addition, a process is disclosed for controlling the flow rate of molten metal from the exit orifice of a closed crucible wherein the total gas and liquid pressure measurement obtained by the high temperature pressure transducer is used as an input into a control circuit which controls the amount of pressurized gas or vacuum applied to the crucible.