Abstract: A temperature sensor for use in measuring the temperature of metal slabs in a reheating furnace is described. The sensor is located in close proximity to the under-surface of the slabs passing through the furnace and immediately below the level of the top of the slab supporting skids. The sensor comprises a metal housing having an open upper end and a metal disc welded to the housing within the opening; a first thermocouple being connected to the undersurface of the disc at its geometrical center and a second thermocouple being connected to the under-surface of the disc at a position displaced from the geometrical center but spaced inwardly from the housing.

Abstract: A distance measuring system, particularly suitable for targets which are moving slowly relative to a fixed reference point, such as the upper surface of the burden in a blast furnace. A doubly modulated microwave beam is directed at the target, and the reflected beam is mixed with part of the original beam, which part has its phase varied sinusoidally at a frequency lower than the modulating frequencies. The difference frequency detected between the phase-varied signal and the reflected signal is directly proportional to the distance to the target.