ORTON Pyrometric Cones

Technical Features

Pyrometric cones are used worldwide to monitor ceramic firings in industrial kilns, ceramic kilns and small hobby kilns where the actual temperature is important to the quality of the final product being fired. Pyrometric cones measure thermal work, the effect of firing time and temperature. Over time, kilns sometimes slowly drift away from their setpoint even though it appears “Nothing has changed”. Pyrometric cones will be the first to indicate that the ceramic firing is under control or that small changes are occurring within the kiln, allowing corrective action before they impact production. LRB type pyrometric cones are made using iron oxide as one of the component materials and for this reason are not suitable for firing in a reducing environment. The practical use of cones is to verify the thermal uniformity and reproducibility of the thermal work provided by a specific heating profile. The final degree of cone bend depends on the rate of heating during the last 100°C of the firing curve and the final temperature. It is important to remember that the cone bends over a fairly small temperature range and that although the degree of cone bend may appear significant it may actually represent only a few degrees of temperature. Most ceramic products are no more sensitive to temperature than the cone as they share many of the same ingredients. The cone value is used to verify that the kiln is delivering the amount of thermal work required by the specific firing curve and to verify that this thermal work is delivered uniformly within the kiln, thanks to the positioning of multiple cones appropriately spaced among the ceramic pieces in the various areas of the firing chamber.