How to distinguish thermocouple model

Commonly used thermocouples can be divided into two categories: standard thermocouples and non-standard thermocouples. The called standard thermocouple refers to the thermocouple whose thermoelectric power and temperature are stipulated in the national standard, which allows for errors, and has a consistent standard indexing table. It has a matching display appearance for selection. Non-standardized thermocouples are not as good as standardized thermocouples in terms of application range or order of magnitude. Generally, there is no consistent indexing table, and they are mainly used for measurement in some special occasions.

The seven standardized thermocouples, S, B, E, K, R, J, and T, are thermocouples of consistent design in China.

The indexing numbers of thermocouples are mainly S, R, B, N, K, E, J, T and so on. In the meantime, S, R, B belong to precious metal thermocouple, and N, K, E, J, T belong to cheap metal thermocouple.

The following is an explanation of the thermocouple index number
  S platinum rhodium 10 pure platinum
  R platinum rhodium 13 pure platinum
  B platinum rhodium 30 platinum rhodium 6
  K Nickel Chromium Nickel Silicon
  T pure copper copper nickel
  J iron copper nickel
  N Ni-Cr-Si Ni-Si
  E nickel-chromium copper-nickel
  (S-type thermocouple) platinum rhodium 10-platinum thermocouple
  The platinum rhodium 10-platinum thermocouple (S-type thermocouple) is a precious metal thermocouple. The diameter of the couple wire is specified as 0.5mm, and the allowable error is -0.015mm. The nominal chemical composition of the positive electrode (SP) is platinum-rhodium alloy with 10% rhodium, 90% platinum, and pure platinum for the negative electrode (SN). Commonly known as single platinum rhodium thermocouple. The long-term maximum operating temperature of this thermocouple is 1300℃, and the short-term maximum operating temperature is 1600℃.