Impervious C799 closed-end protection sheaths and multi-bore insulator rods safeguarding Type R, S, B, and K thermocouples in harsh thermal environments.
Platinum-rhodium noble-metal thermocouples (Types R, S, and B) rapidly poison and drift if exposed to silica vapors, metallic fumes, or reducing contaminants above 1,100 °C. Impervious C799 (99.7% Al2O3) closed-one-end protection sheaths combined with twin-bore or four-bore high-purity alumina capillary insulators isolate bare thermocouple wires electrically and chemically up to 1,750 °C.
Available in metric and fractional inch diameters with round closed domes, optional metal mounting collars, and paired multi-bore inner rods.
| Property / Metric | Nominal Reference Value (Grade Dependent) |
|---|---|
| Material Standard | DIN VDE 0335 C799 (≥99.7% Al2O3) / 99.5% Al2O3 |
| Max Operating Temp | 1,750 °C |
| Gas Tightness | Impervious outer sheath (<10⁻⁸ mbar·L/s He class) |
| Volume Resistivity (1,000 °C) | >10⁶ Ω·cm |
| Bore Configurations | Single COE sheath; 2-hole, 4-hole, 6-hole inner insulators |
Reference values reflect typical sintered, fused, or wrought grades. Exact batch test figures are confirmed on your written quotation and accompanying lot Certificate of Analysis.
Specify outer sheath OD × ID × length (closed-one-end), inner insulator OD × bore diameter × number of bores (2 or 4) × length, thermocouple wire gauge, and operating atmosphere.
Include target quantity, destination country/postal code for express air freight calculation, and any special cleanroom bagging or certification requests.
Prepare Thermocouple Protection Tubes RFQ ↗Complementary furnaceware, substrates, PVD consumables, and refractory hardware frequently ordered together.
TB-AL2O3-TUImpervious high-purity sintered alumina furnace and process tubes for tube furnaces, CVD/annealing, and high-temperature thermal systems.
TB-AL2O3-RDHigh-stiffness solid sintered alumina rods and centerless-ground shafts for kiln supports, vacuum fixtures, metrological guides, and electrical standoffs.
TB-CER-INSCustom-machined electrical, RF, vacuum, and thermal ceramic bushings, flanged washers, standoffs, and heater bobbins built to your engineering drawing.
TB-SIC-CMPExtreme-hardness sintered silicon carbide (SSiC) and thermal-shock-proof silicon nitride (Si3N4) wear components, kiln furniture, seal rings, and molten-metal hardware.
Submit your purity grade, geometry, quantity, and documentation requirements. Every order includes the producing mill's batch Certificate of Analysis (COA) and pre-shipment dimensional verification.