Common thermocouples can be divided into standard thermocouple and non-standard thermocouple. The standard thermocouple refers to the thermocouple whose national standard stipulates the connection between thermal potential and temperature, allows errors, and has a consistent standard graduation table. It has a matching display surface for selection. Nonstandard thermocouples are inferior to standardized thermocouples in application scope or order of magnitude. Generally, there is no consistent scale, which is mainly used in some special occasions.
S. The standardized thermocouples of B, e, K, R, J and T are of the same design type in China.
There are mainly s, R, B, N, K, e, J, t and so on. Among them, s, R, B belong to noble metal thermocouple, N, K, e, J, t belong to base metal thermocouple.
The following is an explanation of the graduation number of the thermocouple
S Platinum Rhodium 10 pure platinum
R platinum rhodium 13 pure platinum
B platinum rhodium 30 platinum rhodium 6
K Ni Cr Ni Si
T pure copper, copper and nickel
J iron copper nickel
Ni Cr Si Ni Si
E nickel chromium copper nickel
(S-type thermocouple) Platinum Rhodium 10 platinum thermocouple
Platinum Rhodium 10 platinum thermocouple (S-type thermocouple) is precious metal thermocouple. The diameter of the coupling wire is specified as 0.5mm, and the allowable error is - 0.015mm. The nominal chemical composition of its positive electrode (SP) is platinum rhodium alloy, which contains 10% rhodium, 90% platinum, and the negative electrode (SN) is pure platinum, so it is commonly known as single platinum rhodium thermocouple. The maximum operating temperature of the thermocouple is 1300 ℃ for a long time and 1600 ℃ for a short time.

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