Introduction to commonly used thermocouples

Commonly used thermocouples include platinum rhodium platinum, nickel chromium alloy (nickel chromium alloy), nickel chromium alloy, iron constantan, etc. Their characteristics and application range are platinum rhodium platinum thermocouples, with a general alloy wire diameter of 0.5 millimeters, high accuracy, large thermoelectric potential, stable performance, good oxidation resistance, and can be used in high-temperature furnaces at 1300 ℃ for a long time. The disadvantage is that it is expensive and cannot be used in a reducing atmosphere. The alloy wire diameter of nickel chromium alloy and nickel chromium alloy thermocouple is 2.5 millimeters, with high thermoelectric potential, high accuracy, low price, good oxidation resistance, and can be used for a long time in furnaces below 900 ℃. The disadvantage is that the material is hard. Nickel chromium alloy copper thermocouple has high thermoelectric potential, high sensitivity, and is inexpensive, making it suitable for use in reducing atmospheres. The operating temperature is below 600 ℃. The disadvantage is that it is prone to oxidation. Iron copper thermocouple is preferred for long-term use in reducing atmospheres with high thermoelectric potential, high sensitivity, low cost, and below 600 ℃. The disadvantage is that it is prone to oxidation