Furnaces

Furnaces are ovens which are used for industrial and laboratory applications. Before choosing a furnace, a number of factors must be taken into consideration. These include the process temperature, the control requirements, pressure range, the dimensions of samples and their inner dimensions. They can be classified according to the size of the chamber, the operating procedure and the atmospheric conditions. There are various types of furnace. The ashing furnace heats samples until only ash remains, which can then be analysed by spectrometers. Its major limitation is that the sample is therefore destroyed. One of the most widespread in use is the tube furnace. Samples are placed in tubes inside the furnace so that their ends protrude and do not get hot. Adapters are put at the ends and reactions can be analysed in a controlled atmosphere. The muffle furnace has mainly high temperature uses such as ignition tests. Melting furnaces are used to melt silver, gold, brass and other metals without the hazard of torch melt. Furnaces are used in quality control laboratories since thermal testing shows up any imperfections. For educational, government and industrial laboratories tube furnaces predominate for purification and syntheses. Dental laboratories apply the techniques of firing and sintering.