Benchmark and Practical Application of State of the Art Hydrogen Monitoring

The knowledge of the hydrogen content in liquid aluminium alloys is a prerequisite for an effective control of the degassing efficiency and therefore the quality of the final product. This paper describes the procedure and the results of an extensive benchmark study on the most common devices for online measurement of hydrogen in casting launders, Alscan and Hycal. Both devices were tested in lab scale experiments at various known hydrogen levels, which were established by purging with different reference gas mixtures until equilibrium. In addition, extensive tests were carried out in a pilot casting facility as well as in a production cast shop on different alloys and in various positions between holding furnace and casting station. The results of these tests as well as the consequences for the following implementation and automation of the selected device are part of this paper.