Sand Baths Provide Precise Heating Performance

Four Techne fluidised sand baths are providing the materials laboratory at Cambridge University’s Department of Engineering with precisely controlled heating facilities for a wide variety of heat treatment processes up to 600°C with temperature accuracy within ±1°C. The SBL-2 sand baths are mainly used by students for tempering, annealing, stress-relieving and other procedures on steel, aluminium, brass and copper in a wide range of grades as part of their engineering degree courses. Staff use the equipment to heat metallic and non-metallic materials for research purposes.

Samples are typically held in perforated metal containers suspended in the sand from supports at the top of a stainless steel cylinder containing particles of aluminium oxide. Air is blown through the sand to create a boiling effect similar to a liquid bath but without the fumes associated with oil baths and the solidification that occurs with salt baths. As the sand is heated, the heat is distributed throughout the bath and transferred quickly and evenly to the samples in it. Temperature control is provided by Techne TC-8D wall-mounted instruments via type K thermocouples that fit into a pocket in each bath wall. The bench-top units have an internal diameter of 228mm and depth of 140mm. Heating is provided by three 1kW elements that enable maximum temperature to be reached from ambient in approximately 100 minutes. The inner chamber is insulated from the outer wall, and the elements cut off if the air supply fails.