What does "division number" mean for thermocouples and temperature measuring instruments?
The division numbers of thermocouples mainly include S R. B, N, K, E, J, T, etc. Among them, S R. B belongs to precious metal thermocouples, N. K, E, J, and T belong to cheap metal thermocouples.
The characteristic of S grade is strong antioxidant performance, and it is suitable for continuous use in oxidizing and inert atmospheres. The long-term use temperature is 1400 ℃, and the short-term use temperature is 1600 ℃. Among all thermocouples, The accuracy level of the S-scale is the highest and is usually used as a standard thermocouple;
Compared to the S index, the R index has a thermal electromotive force that is about 15% higher, and its other performance is almost identical;
The thermal electromotive force of the B index is extremely small at room temperature, so compensation wires are generally not needed during measurement. Its long-term usage temperature is 1600 ℃ and short-term usage temperature is 1800 ℃. It can be used in oxidizing or neutral atmospheres, as well as for short-term use under vacuum conditions.
The characteristics of the N-grade thermocouple are strong high-temperature oxidation resistance at 1300 ℃, good long-term stability of thermoelectric force and reproducibility of short-term thermal cycles, good resistance to nuclear radiation and low temperature, and can partially replace the S-grade thermocouple;
The characteristic of K scale is strong antioxidant performance, and it is suitable for continuous use in oxidizing and inert atmospheres. The long-term use temperature is 1000 ℃, and the short-term use temperature is 1200 ℃. Widely used in all thermocouples;
The characteristic of the E-scale is that in commonly used thermocouples, its thermoelectric electromotive force * is large, that is, its sensitivity * is high. It is recommended to use continuously in an oxidizing and inert atmosphere at a temperature of 0-800 ℃;
The characteristic of J-grade is that it can be used in both oxidizing atmospheres (with an upper temperature limit of 750 ℃) and reducing atmospheres (with an upper temperature limit of 950 ℃), and is resistant to H2 and CO gas corrosion. It is mostly used in refining and chemical industry;
The characteristic of T-scale is that it has a high degree rating among all cheap metal thermocouples and is usually used to measure temperatures below 300 ℃.
