Thermocouple Types

Mike · November 21, 2018, 5:56am

Many combinations of materials have been used to produce acceptable thermocouples, each with its own particular application spectrum. However, very few specific types are now easily available, and covering by far the majority of the temperature and environmental applications.

The standard covers the eight specified and most commonly used thermocouples. These thermocouple types can be subdivided in 3 groups, base metal, Noble (rare) metal and Refractory metal thermocouple.

Base Metal Thermocouples

Base metal thermocouple types are composed of common, inexpensive metals such as nickel, iron and copper. The thermocouple types E, J, K, N and T are among this group and are the most commonly used type of thermocouple.

Noble Metal Thermocouples

Noble metal thermocouples are manufactured with wire that is made with precious or “noble” metals like Platinum and Rhodium. The main types are R, S and B.

Refractory Metal Thermocouples

Refractory metal thermocouples are manufactured with the exotic metals tungsten and Rhenium. These metals are expensive, difficult to manufacture and wire made with these metals are very brittle.

Thermocouple Type	Material + & -	Temperature Range ( º C)	Application
E	Chromel & Constantan (Ni-Cr & Cu-Ni)	-200 to 900º C	Inert media, Oxidizing media
J	Iron & Constantan (Fe & Cu-Ni)	0 to 750ºC	Inert media, Oxidizing media, Reducing media Vacuum
K	Chromel & Alumel (Ni-Cr & Ni-AI)	-200 to 1250ºC	Inert media, Oxidizing media
N	Nicrosil & Nisil (Ni-Cr & Ni-Si)	-270 to 1300ºC	Inert media, Oxidizing media
T	Copper & Constantan (Cu & Cu-Ni)	-200 to 350ºC	Inert media, Oxidizing media, Reducing media Vacuum
R	87% Platinum/13% Rhodium &