A platinum10 rhodiumplatinum type S thermocouple is used to

A platinum/10% rhodium-platinum (type S) thermocouple is used to measure the temperature of a furnance. The output emf, with the reference junction maintained at 50 degrees C, is 5.975 mV.

What is the temperature of the furnance?

Solution

From the Thermocouple voltage-temperature table given for S-Type thermocouples on the internet, 5.971 mV corresponds to 671^o C and 5.982 mV corresponds to 672^o C.

T - T₀ = T_L + [(V - V_L ) / (V_H - V_L)] * (T_H - T_L)

T₀ = 50 ; V = 5.975 mV ; V_L = 5.971 mV ; V_H = 5.982 mV ; T_H = 672^o C ; T_L = 671^o C

T - 50 = 671 + [ (5.975 - 5.971) / (5.982 - 5.971) ] * (672 - 671)

=> T - 50 = 671 + 0.37

=> T = 721.37^o C