Thermocouple type K (NiCr-Ni)

For which application is a thermocouple type K suitable?

A type K thermocouple (NiCr-Ni or nickel-chromium / nickel-aluminum) is one of the most common and widely used thermocouples due to its versatility. Due to their material composition, NiCr-Ni thermocouples according to DIN EN 60584 are suitable for applications at higher temperatures in clean, oxidizing (air) and neutral atmospheres (inert gases). The standardized temperature range of the type K thermocouple is -270°C to +1372°C.

Type K thermocouples have an operating temperature range, described in the standard DIN EN 60584, from -40 to +1000°C (in class 1) and a limiting deviation of ±1.5°C or 0.40%. The temperature range of a type K thermocouple is -40 to +1200°C in class 2. The temperature deviation (limit deviation) is ±2.5°C or 0.75%.

What is the structure of a type K thermocouple (NiCr-Ni)?

The legs of a type K thermocouple (positive leg: green; negative leg: white) are made of the following materials:

Type K (+) leg (NiCr):
89-90% nickel, 9-9.5% chromium, 0.5% each silicon and iron, balance: C, Mn, Nb, Co.

Type K (-) leg (Ni):
95-96% nickel, 1-1.5% silicon, 1-2.3% aluminum, 1-3.2% manganese, 0.5% cobalt, balance: Fe, Cu, Pb.

An overview of other thermocouples for thermocouples with general properties, the temperature range, material composition as well as advantages and areas of application can be found in the table Overview thermocouples. Information on the electrical voltage of thermocouples can be found in the table Thermoelectric voltage.

Thermocouple type K properties and areas of application.
Color code	Technical characteristics of a thermocouple type K
Color code	material	temperature range	Application temperature range in class 1	Limit deviation in class 1	Application temperature range in class 2	Limit deviation in class 2
Type K	NiCr-Ni	-270°C/+1372°C	-40 to +1000°C	±1,5°C or 0,40%	-40 to +1200°C	±2,5°C or 0,75%

Types and designs of thermocouples type K (NiCr-Ni)

Depending on the application and temperature range, type K thermocouples can be used with a connection cable, a thermocouple plug, a protection tube and a connection head. In the following overview you will find common thermocouples or sheathed thermocouples type K, which are often used.