Type K Thermocouple - Temperature Sensors / Probes
Type K - Nickel-Chromium vs Nickel-Aluminium
Thermocouple Type K, generally referred to as Chromel-Alumel, is the most common thermocouple in use today. Type K thermocouples are designed primarily for general temperature measurements in normal atmospheres. Maximum continuous temperature is about 1,100°C, although above 800°C oxidation increasingly causes drift and decalibration. For short term exposure, however, there is a small extension to 1,200°C. The device is also suitable for cryogenic applications down to -250°C.
Although theType K thermocouple is widely used because of its wide temperature range and cheapness, it is not as stable as other base metal sensors in common use. At temperatures between 250°C and 600°C, but especially 300°C and 550°C, temperature cycling hysteresis can result in errors of several degrees. A Type K thermocouple should not be used in reducing atmospheres unless protected by a suitable sheath and whilst Type K thermocouples are popular for nuclear applications because of its relative radiation hardness, Type N is a better choice for those applications.
Type K Thermocouples - Typical Constructions and Styles
Type K Mineral InsulatedThermocouples

Rugged sensors, ideal for most applications. Vast choice of terminations e.g. pot seals, cables, connectors, heads etc.
Type K Swaged TipThermocouples

Fast response thermocouples ideal for industrial and other applications.
Type K MiniatureThermocouples

Ideal for precision temperature measurements where minimal displacement and a fast response is required.
Type K Heavy DutyThermocouples

For industrial applications such as furnaces, kilns, ovens, boilers, flues etc. Many types of sheath material available.
General PurposeType K Thermocouples

A wide range of thermocouples to suit many applications. Hand held, surface, bayonet, bolt, patch styles etc.
ATEX/IECEx ApprovedType K Thermocouples

A large range of thermocouples with a variety of terminations such as pot seal, terminal heads etc.
Type K - Technical Data
Conductor Combination | Approximate generated EMF change in µV per ºC change (referenced to 0ºC) at: |
Approximate Working Temperature Range |
Initial Calibration Tolerances to ASTM E-230 (whichever is greater) |
Thermocouple Output Tolerances to IEC 60584-1 |
||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
+ Leg | - Leg | 100ºC | 500ºC | 1000ºC | ºF | ºC | Standard | Special | Type | Class 1 | Class 2 | Class 3 |
NICKEL - CHROMIUM Also known as: Chromel™, Thermokanthal KP*, NiCr, T1*, Tophel™ | NICKEL - ALUMINIUM (magnetic) Also known as: Ni-Al, Alumel™, Thermokanthal KN™, T2™, NiAl™ |
42 | 43 | 39 | 32 to 2300 | 0 to 1260 | ±2.2 or ±0.75% | ±1.1 or ±0.4% | Temperature Range Tolerance Value Temperature Range Tolerance Value |
–40°C to +375°C ±1.5°C 375°C to 1000°C ±0.004 ⋅ [t] |
–40°C to +333°C ±2.5°C 333°C to 1200°C ±0.0075 ⋅ [t] |
–167°C to +40°C ±2.5°C –200°C to –167°C ±0.015 ⋅ [t] |
2. Thermocouple materials are normally supplied to meet the tolerances specified in the table for temperatures above –40 deg C. These materials however, may not fall within the tolerances for low temperatures given under Class 3 for Types T, E and K thermocouples. If thermocouples are required to meet limits of Class 3, as well as those of Class 1 and/or Class 2, the purchaser should state this, as selection of materials is usually required.
What Color is Type K Thermocouple Wire?
IEC 60584-3 provides tolerances and identification for a common international system for thermocouple wire identification and tolerances based essentially on thermoelectric emf as opposed to a datum of the emf of the thermo elements against platinum. Tolerances are defined as the maximum allowable deviation in microvolts, caused by the introduction of extension or compensating extension wire into the circuit. Color codes and tolerances are well established in the United States and have been in use as a national standard for years. In other parts of the world, there are alternative color code systems and tolerances, either in use, or in the process of being implemented. One such color code system is that established by the IEC.
In the United States, color codes and tolerances are defined in ANSI 96.1 (1982) and ASTM E-230. Extension wire and compensating extension wire is indicated with the letter “X” after the thermocouple type per these standards. The color code for thermocouple grade wire includes a brown overall jacket whereas the color code for thermocouple extension wire typically includes an overall jacket in the color of the positive wire. For some insulations, colors may appear as a stripe or trace strand. High temperature braided insulation is not normally color coded.
The table below shows the color coding adopted by the ASTM and IEC. Please click here for all thermocouple wire colour codes.
ANSI MC96.1 United States | International
Color Code to IEC 60584-3 |
Redundant national colors | ||
---|---|---|---|---|
Thermocouple Grade | Extension Grade | BS 1843 | DIN 43714 | ![]() | ![]() | ![]() | ![]() | ![]() |
Thermocouple Wire Available From Stock
Heat ResistantPVC Insulated

PVC Insulated

Low Smoke and Fume

Insulated


Braided Cables

Common Type K Thermocouple Sensors for Temperature Measurement Applications
Type K thermocouples with Basic End Seal 0.010" to 0.313" dia.
Internal seal with bare conductors
Type K thermocouples with Pot Seal 0.010" to 0.313" dia.
a large selection of plain and threaded pot seals supplied with tails or extension Wire (PVC, FEP, Fiberglass etc.)
Type K thermocouples with Miniature Plug 0.010" to 0.125" dia.
fitted with a miniature thermocouple plug rated to either 428ºF, 572ºF, 797ºF or 1112ºF
Type K thermocouples with Miniature Jack 0.010" to 0.125" dia.
fitted with a miniature thermocouple jack rated to either 428ºF, 572ºF, 797ºF or 1112ºF
Type K thermocouples with Standard Plug 0.062" to 0.250" dia.
fitted with a standard thermocouple plug rated to either 428ºF, 572ºF, 797ºF or 1112ºF
Type K thermocoupleswith Standard Jack 0.062" to 0.250" dia.
fitted with a standard thermocouple jack rated to either 428ºF, 572ºF, 797ºF or 1112ºF
Type K thermocouples with Lemo Connector 0.125" to 0.250" dia.
fitted with a size 1 Lemo plug
or jack Type K thermocouples with Terminal Entry Gland 0.040" to 0.313" dia.

terminated with a 16mm ISO x 1.5mm compression gland seal supplied with tails or extension Wire (PVC, FEP Fiberglass etc.)
Type K thermocouples with Micro die cast alloy head 0.125" to 0.250" dia.
Micro die cast alloy screw down terminal head with ceramic terminal block. Suitable for simplex and duplex assemblies
Type K thermocoupleswith Miniature IP67 die cast head 0.125" to 0.313" dia.






