Ceramic Protecting Tube Characteristics
Thermo Sensors Corporation ceramic tubes are high quality, fine grained, non-porous tubes. They are impervious to gases at temperatures near their melting point. Materials available range from mullite (C3 Ceramic) to high purity alumina (C98 Ceramic). Material selection depends upon operating conditions and performance requirements such as temperature, atmosphere, sensitivity to contamination and others.
C30 Ceramic (Mullite)
Maximum operating temperature of 2900° F (1600° C). Impervious to air to 3000° F, to dry hydrogen and carbon monoxide to 2550° F. Low rate of thermal expansion (2.8 x 10-6/° F) enhances thermal shock resistance. Resistance to acid slag is good. Basic slag is fair. Recommended for J, K, N, and E type thermocouples.
C98 Ceramic (99.8% alumina)
Maximum operating temperature 3450° F (1900° C) in both oxidizing and reducing atmospheres. Inert to hydrogen, carbon, platinum, rhodium and refractory metals under most conditions. High thermal conductivity for fast temperature response. Being more dense than C30, affords longer life in acids, alkalis, molten metals, molten salts and slags. Impervious to most industrial furnace gases even at high temperatures. Recommended for R, S and B type thermocouples.
MCT Metal – Ceramic (LT-1)
Maximum operating temperature of 2800° F (1538° C). This tube is a combination of aluminum oxide and chromium. Stable in oxidizing atmospheres to 2200° F. Thermal and mechanical shock characteristics are better than pure ceramic tubes, but an extreme temperature span requires a slow insertion time to allow tube to preheat. Sulphur dioxide, sulphur trioxide and concentrated sulphuric acids have little effect on MCT tubes. Since copper, zinc, lead, brass and ferrous alloys do not “wet” MCT tubes their life is longer in such melts, abrasive resistance even at 2200° F. Do not use in acid or carbide slags or molten aluminum.
SCT (Silicon Carbide)
Maximum operating temperature of 3000° F (1649° C). Suggested as primary tube in molten aluminum. Porous and affords protection from flame cutting. A secondary tube to provide thermal and mechanical shock resistance in assemblies using C30 and C98 as a primary.
