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Applications and Classification of Thermocouple Protection Tubes Insulation sleeves serve to prevent short circuits between the two thermoelectric junctions or between those junctions and the protection sleeve. The material of the insulating sleeve is determined by the operating temperature range: ordinary ceramics are commonly used below 1000° ； High-purity alumina is commonly used between 1000–1300° ； Between 1300–1600°, corundum is commonly used, while organic materials are typically used as the insulating material for compensation wires. Insulating protective tube: Its function is to prevent the thermocouple from coming into direct contact with the medium being measured, thereby avoiding mechanical damage or corrosion and contamination by the medium. It can be seen that the protective tube is crucial for thermocouples to be used in harsh and special environments. The material of the protective tube is generally determined based on factors such as the measurement range, the length of the heating zone, the ambient atmosphere, and the time constant of temperature measurement; the main types are metal, non-metal, and cerametal. 1. Metal materials, such as steel pipes, seamless smooth pipes, stainless smooth pipes, and heat-resistant smooth pipes, etc. Metal protective tubes are characterized by high mechanical strength, good toughness, and strong resistance to slag corrosion; therefore, they are mostly used in applications that require sufficient mechanical strength. However, their airtightness decreases above 800°. 2. Non-metallic materials. Non-metallic protective tubes mainly include high-melting-point oxides and composite oxides, such as Al2O3/SiO2, MgO/ZrO2/BeO, etc ； Nitrides, such as Si3N4, BN, etc ； Carbides, such as SIC, etc., and borides such as ZrB2, etc. Non-metallic protective tubes are mainly used in high temperatures, and can also be employed in low temperatures where metal sleeves are not suitable. It has strong resistance to corrosion, but its texture is relatively brittle. 3. Cerammetics. Although thermocouple metal materials are tough, they are often not resistant to high temperatures and have poor corrosion resistance. Ceramic materials are the exact opposite: they can withstand high temperatures and resist corrosion, but they are very brittle. To this end, metals and ceramics were combined to take advantage of their respective strengths, resulting in a durable material known as cermets, which is resistant to high temperatures, corrosion, and thermal shock. Cerammetics refer to a heterogeneous composite material composed of a metal or alloy together with one or several ceramic materials. The main ones include AL2O3-based cermets, ZRO2-based cermets, MgO-based cermets, and titanium carbide-based cermets. Cerametallic protection tubes are commonly used for temperature measurement in chemical plants, as well as in molten metal and high-temperature furnaces. For more information, please visit the company’s official website at http://www.yb1518.com/. Please retain this link when reproducing the content! http://www.yb1518.com/UploadFiles/20108515027944.jpg