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 StylesType K Mineral Insulated
Rugged sensors, ideal for most applications. Vast choice of terminations e.g. pot seals, cables, connectors, heads etc.Type K Swaged Tip
Fast response thermocouples ideal for industrial and other applications.Type K Miniature
Ideal for precision temperature measurements where minimal displacement and a fast response is required.Type K Heavy Duty
For industrial applications such as furnaces, kilns, ovens, boilers, flues etc. Many types of sheath material available.General Purpose
Type K Thermocouples
A wide range of thermocouples to suit many applications. Hand held, surface, bayonet, bolt, patch styles etc.ATEX/IECEx Approved
Type 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:
|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,
|NICKEL - ALUMINIUM
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
|–40°C to +375°C
375°C to 1000°C
±0.004 ⋅ [t]
|–40°C to +333°C
333°C to 1200°C
±0.0075 ⋅ [t]
|–167°C to +40°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
to IEC 60584-3
|Redundant national colors|
|Thermocouple Grade||Extension Grade||BS 1843||DIN 43714|
Thermocouple Wire Available From StockHeat Resistant
A wide range of HR PVC insulated Wire. constructions such as 'Parallel Construction', Twisted', Screened and Armored Wire is available. Flame Retardant
PVC Insulated FR PVC in Screened and Armored constructions. Meeting IEC 60332.1:2004 covering tests on Wire under fire conditions. Fire Resistant MICA/XLPE
Low Smoke and Fume
Fire Resistant MICA/XLPE Low Smoke and Fume Single Pairs. Incorporates high temperature MICA glass tape. Halogen free. PFA
Insulated A wide range of PFA insulated Wire. constructions such as 'Parallel Construction', Twisted' and Screened Wire is available. Fiberglass and Ceramic Fibre InsulatedA range of 'Parallel Construction' and braided constructions in standard (480ºC) or High Temperature (800ºC) Fiberglass, Plus Ceramic Fibre (1400ºC). Stainless Steel
Braided Cables Stainless Steel Braided PVC, PFA and Fiberglass insulated cables.
Common Type K Thermocouple Sensors for Temperature Measurement ApplicationsType K thermocouples with Basic End Seal 0.010" to 0.313" dia.
Internal seal with bare conductorsType 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 1112ºFType K thermocouples with Miniature Jack 0.010" to 0.125" dia.
fitted with a miniature thermocouple jack rated to either 428ºF, 572ºF, 797ºF or 1112ºFType K thermocouples with Standard Plug 0.062" to 0.250" dia.
fitted with a standard thermocouple plug rated to either 428ºF, 572ºF, 797ºF or 1112ºFType K thermocoupleswith Standard Jack 0.062" to 0.250" dia.
fitted with a standard thermocouple jack rated to either 428ºF, 572ºF, 797ºF or 1112ºFType 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 assembliesType K thermocoupleswith Miniature IP67 die cast head 0.125" to 0.313" dia.Weatherproof die cast alloy screw top terminal head with ceramic terminal block. Suitable for simplex and duplex assemblies Type K thermocouples with Standard IP67 die cast head 0.188" to 0.500" dia. Weatherproof die cast alloy screw top terminal head with ceramic terminal block. Suitable for simplex, duplex and triplex assemblies Type K thermocouples with IP67 heavy duty cast iron head 0.188" to 0.500"dia. Weatherproof cast iron screw top terminal head with ceramic terminal block. Suitable for simplex, duplex and triplex assemblies Type K thermocoupleswith IP67 Bakelite head 0.188" to 0.500"dia.Weatherproof Bakelite screw top terminal head with Bakelite terminal block. Suitable for simplex, duplex and triplex assemblies Type K thermocoupleswith alloy straight through head 0.188" to 0.500"dia.Die cast alloy straight through terminal head with Bakelite terminal block. Suitable for simplex and duplex assemblies Type K thermocouples with 316 Stainless Steel head 0.188" to 0.500"dia. Weatherproof 316 stainless steel screw top terminal head with ceramic terminal block. Suitable for simplex and duplex assemblies Type K thermocoupleswith BUZ-H style top hat head 0.188" to 0.500"dia. Weatherproof die cast alloy screw down 'flip' terminal head. Mainly used for duplex assemblies where two transmitters can be fitted Type K thermocoupleswith spring loaded terminal block 0.125", 0.188", 0.250" and 0.313" dia.Spring loaded insert assemblies. The end seal is incorporated into a terminal block for mounting into any standard terminal head