Introduction to Ceramic and Silicon Carbide Protection Tubes In applications where contamination from hostile environments is a factor; the use of ceramic and silicon carbide protection tubes is recommended. Hostile conditions can also exceed the melting points of common metals and require the use of noble metal thermocouples (platinum and its alloys). Traditionally, such assemblies include one or two inner porcelain tubes and one outer silicon carbide tube. Protection Tube Selection Protection tubes must be selected based on the intended application and the maximum temperatures expected. Tube materials react differently to high temperatures. At elevated temperatures certain ceramic materials pass through a glass phase. Alumina protection tubes and element insulators are recommended for applications with temperatures exceeding 2400°F (1316°C) Glazed tubes are not recommended for any application involving noble metals www.tcproducts.com a division of Marsh Bellofram www.marshbellofram.com 1-800-727-5646 Thermo-Couple Products Co. 81

www.tcproducts.com a division of Marsh Bellofram www.marshbellofram.com Thermo-Couple Products Co. 1-800-727-5646 80 Protection Tubes are made out of metal, ceramic (mullite), or metalceramic (LT-1) material. The table below will be helpful when selection metal or metal-ceramic protection tubes. On page 82, information pertaining to ceramic protection tubes can be found. Metal and Metal-Ceramic Protection Tube Application Data Material Recommended Maximum Temperature Remarks Carbon Steel 1000°F (540°C) Satisfactory in any except corrosive atmospheres. Monel (67% Nickel, 30% Copper) 900°F (480°C)...

www.tcproducts.com a division of Marsh Bellofram www.marshbellofram.com Thermo-Couple Products Co. 1-800-727-5646 82 METAL PROTECTION TUBES 7000 1 - 24 - C - 0 Series 7000 • Protection Tubes Help Insure Longer Life and Continued Accuracy • Protects Against Physical Damage, Corrosion, and Contamination • Generally Less Expensive than Thermowells ! Metric Ord e rs Welcome Place an mm in the appropriate selection box: Enter a selection for each item, please fax your inquiry to TCP. 7000 - Example: - - - CODE OTHER PERTINENT DATA 0 999 NONE Special Request Consult Factory CODE WIRE GAUGE SIZE A C...

www.tcproducts.com a division of Marsh Bellofram www.marshbellofram.com 1-800-727-5646 Thermo-Couple Products Co. 83 CERAMIC PROTECTION TUBES 7100 1 - P - 12 - A Series 7100 • Manufactured Under Rigid Controls to Maintain High Quality • Provides Protection at High Temperatures - Alumina 3450°F - Ceramic 3100°K - Silicon Carbide 3000°F Enter a selection for each item, please fax your inquiry to TCP. 7100 - Example: - - - CODE MATERIAL A C SC Aluminum Oxide Ceramic (Mullite) Silicon Carbide CODE LENGTH “L” 12 18 24 30 36 42 48 60 66 12" 18" 24" 30" 36" 42" 48" 60" 66" PROTECTION TUBE SIZE CODE...