What is a horizontal tube furnace?

What is a horizontal tube furnace?
A horizontal tube furnace is an electric thermal processing solution with a characteristic heating chamber comprised of a continuous piece of high-temperature insulation, or two semi-cylindrical elements. They are often consequently defined as either solid or split tube furnaces.

In either type, the term horizontal refers to the orientation of the cylinder length. There is typically a central hot zone (or zones) and accessible end or top plugs that may protrude from the furnace body for easy access to the processing chamber. This configuration is most common in solid tube furnaces, as split tubes provide access to the recessed chamber by hinging open.
Furnaces designed for use at 1200°C or less feature wire wound refractory metals heaters. These are typically embedded into the insulated chamber walls to maximise space and thermal uniformity. Furnaces designed for higher use temperatures feature either silicon carbide or molydisilicide heating elements suspended from the furnace roof in arrays along both sides of the tube.