Type K Thermocouple - Technical Information
Type K - Nickel-Chromium vs Nickel-Aluminium, IEC 60584-1
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.
Although Type K 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. Type K thermocouples 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, boliers, 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.
K Type Thermocouple - Technical Data
| Conductor Combination | Approximate generated EMF change in µV per ºC change (referenced to 0ºC) at: |
Approximate Working Temperature Range |
Thermocouple Output Tolerances to IEC 60584-1 | |||||||
|---|---|---|---|---|---|---|---|---|---|---|
| + Leg | - Leg | 100ºC | 500ºC | 1000ºC | Continuous | Short Term | 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 | 0 to +1100ºC | -180 to +1350ºC | 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.
Cable Colour Codes
| International Colour Code to IEC 60584-3 | ANSI/MC96.1 | Redundant national colour coding for thermocouple cables | ||
|---|---|---|---|---|
| BS 1843 | DIN 43714 | NFC 42324 | ||
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