1. Temperature Resistance and Environment Adaptation: Prioritize matching the maximum furnace temperature (e.g., S/B-type platinum-rhodium thermocouples for high-temperature furnaces, K-type nickel-chromium-nickel-silicon for medium-temperature furnaces). Avoid nickel-based thermocouples in hydrogen/carbon-containing atmospheres (prone to carburization and embrittlement); select platinum-rhodium or tungsten-rhenium materials instead.
2. Accuracy Class: Must use ClassⅠaccuracy (smaller tolerance) to ensure consistency of multi-point measurement data, complying with furnace temperature uniformity testing standards such as AMS 2750E and GB/T 9452.
3. Structure and Installation: Adopt bare or thin-walled protection tubes (reducing thermal response lag), ensure consistent probe lengths (avoiding errors caused by different insertion depths), and install at uniformly distributed key positions (four corners, center, edge of the furnace chamber, etc.).
4. Stability and Calibration: Choose materials with good long-term stability (e.g., platinum-rhodium thermocouples with strong oxidation resistance). Complete multi-point calibration according to testing standards before use to ensure thermoelectric potential drift is within the allowable range.
5. Wires and Compensation: Use compensation wires of the same type, avoid intermediate joints, and ensure consistent polarity between compensation wires and thermocouples to reduce the impact of cold junction temperature error on uniformity judgment.