Thermocouple Types and Comparison

Thermocouple types and probes and thermocouple cables used for measurement of temperature, mode of furnace thermocouple working and high temperature thermocouples working procedure, functioning of termistor. Calibration of temperature sensors, material of construction of various thermocouple based on the utilisation, mechanism of fitting the thermocouple to the process equipments and working principle of thermocouple testing. B,E,J,K,R,S,T types of thermocouple comparison

Sr no	Type	Positive wire	Negative wire	Temperature range 0C	Linearity
1	B	Pt-70—Rh-30	Pt-94—Rh-6	0 to 1860	Good at high temperature
2	E	Chromel	Constantan	-196 to 999	Good
3	J	Iron	Constantan	-196 to 760	Nearly linear between 149 to 438
4	K	Chromel	Alumel	-190 to 1371	Most linear
5	R	Pt-87—Rh-13	Platinum	-18 to 1704	Good at high temperature
6	S	Pt-90—Rh-10	Platinum	-18 to 1760	Good at high temperature
7	T	Copper	Constantan	-190 to 399	Same as J
8		Tungsten W	W 74 –Re 26	-18 to 2316	Good at high temperature
9		W 94 –Re 6	W 74 –Re 26	-18 to 2316	Good at high temperature
10		Copper	Gold – Cobalt	-268 to -18	Linear above 60k
11		Ir 40- Rh 60	Ir	-18 to 2093	Good at high temperature

Pt- Platinum
Rh- Rhodium
W- Tungsten
Re- Rhenium
Ir-Iridium

At various corrosive environments the instrument should function and measure the temperature, for that purpose a list of thermocouple will help to determine the right suitable temperature measuring instrument.

Sr no	Type	Positive wire	Negative wire	Suitable atmosphere
1	B	Pt-70—Rh-30	Pt-94—Rh-6	Inert or slow oxidizing
2	E	Chromel	Constantan	Oxidizing
3	J	Iron	Constantan	Reducing
4	K	Chromel	Alumel	Oxidizing
5	R	Pt-87—Rh-13	Platinum	Oxidizing (fast response)
6	S	Pt-90—Rh-10	Platinum	Oxidizing
7	T	Copper	Constantan	Oxidizing or reducing(good corrosion resistance)
8	Y	Iron	Constantan	Reducing
9	--	Tungsten W	W 74 –Re 26	Inert or vacuum(high temperature)