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Type K Thermocouple – Chromel Alumel Temperature Sensor

Type K (NiCr–NiAl) | IEC 60584-1 Standard

Type K Thermocouple – Key Facts

Thermocouple Type: K (Chromel–Alumel)
Temperature Range: 0 to 1100°C (continuous), -180 to +1350°C (short-term, application dependent)
Accuracy (IEC 60584-1): Class 1 ±1.5°C or 0.4%, Class 2 ±2.5°C or 0.75%
Typical Applications: Industrial process, scientific, and general-purpose temperature measurement
Limitations: Not suitable for reducing or sulphurous atmospheres without protection
Response Time: Fast response, dependent on probe design and junction type
Configurations: Mineral insulated, miniature, surface, hand-held, heavy-duty, and ATEX/IECEx-approved designs
Availability: Manufactured and supplied in a wide range of probe types, sheath materials, and terminations

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Type K Thermocouple – Chromel Alumel temperature sensor with stainless steel sheath — Examples of Type K Thermocouples (Chromel–Alumel), the most widely used industrial temperature sensor.

Key Specifications

Temp Range

-180°C to 1350°C

Accuracy Class

Class 1 & 2 (IEC)

Sensitivity

~41 µV/°C

Sheath Materials

Stainless Steel, Inconel

Type K thermocouples (Chromel–Alumel) are widely used general-purpose temperature sensors offering a wide operating range, fast response, and excellent resilience. They are ideal for industrial, scientific, and engineering applications where reliable temperature measurement is required.

They can measure up to 1,100°C continuously, with short-term limits up to 1,350°C. Above 800°C, oxidation may reduce accuracy over time. Not suitable for reducing or sulphurous atmospheres without protective sheath. For radiation resistance applications, Type N thermocouples may offer better stability.

Manufactured in the UK

Available in mineral insulated, heavy duty, surface, miniature, ATEX/IECEx approved, all in custom configurations.

Fast manufacture
Custom lengths, diameters, sheath materials, end seals, cables, head etc.
UKAS calibration available

Popular Type K Thermocouple Sensors

Choose from the categories shown below and custom build as required:

Type K Mineral Insulated Thermocouples

Type K thermocouple – mineral insulated probe with stainless steel sheath for high-temperature measurement

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

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Type K Swaged Tip Thermocouples

Type K thermocouple – swaged tip fast-response temperature sensor for industrial applications

Fast response thermocouples ideal for industrial and other applications.

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Type K Miniature Thermocouples

Type K miniature thermocouple – compact probe for tight-space and precision measurements

Ideal for precision temperature measurements where minimal displacement and a fast response is required.

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Type K Heavy Duty Thermocouples

Type K heavy duty thermocouple – robust temperature probe with industrial head for harsh environments

For industrial applications such as furnaces, kilns, ovens, boliers, flues etc. Many types of sheath material available.

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General Purpose Type K Thermocouples

General purpose Type K thermocouple – versatile temperature probe for wide-range industrial use

A wide range of thermocouples to suit many applications. Hand held, surface, bayonet, bolt, patch styles etc.

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ATEX/IECEx Approved Type K Thermocouples

Type K thermocouple – ATEX and IECEx approved probe for hazardous and explosive atmospheres

A large range of thermocouples with a variety of terminations such as pot seal, terminal heads etc.

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Technical Specifications

Conductors: Positive: Nickel-Chromium (Chromel), Negative: Nickel-Aluminium (Alumel)
Temperature range: Continuous 0–1100°C, Short-term -180–1350°C
Accuracy: Class 1 ±1.5°C, Class 2 ±2.5°C, Class 3 ±2.5°C to -167°C
Output voltage: See Type K Thermocouple EMF Table (100°C → 4.096 mV, 500°C → 20.644 mV, 1000°C → 41.276 mV)
Colour code: IEC 60584-3: Green (+), White (-); ANSI: Yellow (+), Red (-)

Comparison with Type N

Feature	Type K	Type N
Temperature Range	0–1100°C	0–1200°C
Best for	General industrial	High-temp stability and reducing atmospheres
Atmosphere	Oxidising	Oxidising and reducing

Everything you need to know about thermocouples and RTDs
Explore our in-depth Thermocouple & RTD Guide — a technical resource developed for engineers and specifiers. Covers sensor selection, installation practices, standards and tolerances, colour codes, wiring configurations, sensor theory and more.

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Frequently Asked Questions

What is a Type K thermocouple used for?
A Type K thermocouple is widely used for industrial, scientific, and general temperature measurement applications. It is commonly found in furnaces, kilns, engines, HVAC systems, metal processing, and food industry applications due to its high-temperature range and reliability.
Can you manufacture custom Type K thermocouples?
Yes — we manufacture custom Type K thermocouples in the UK, including bespoke lengths, diameters, sheaths, connectors, and terminations. Send your drawing or specification for a fast quotation or complete a Product Enquiry from any of our sensor pages.
Do you supply Type K thermocouple probes with calibration?
Yes — UKAS calibration and full traceability are available for all Type K probes.
What is the temperature range of a Type K thermocouple?
The typical temperature range of a Type K thermocouple is:
Continuous use: 0ºC to 1100ºC
Short-term exposure: -180ºC to 1350ºC
However, the practical range of any thermocouple also depends on factors like sheath material, wire thickness, and environmental conditions.
How accurate is a Type K thermocouple?
Accuracy as defined by the IEC 60584-1 standard is as follows:
Class 1: ±1.5ºC or 0.4% of the reading (whichever is greater)
Class 2: ±2.5ºC or 0.75% of the reading
Class 3: ±2.5ºC down to -167ºC
For maximum accuracy, calibration is recommended.
Why is Type K the most commonly used thermocouple?
Type K is the most popular thermocouple because it is: affordable compared to platinum-based thermocouples, durable in oxidizing atmospheres, capable of high-temperature measurements and widely available in different probe types.
Can Type K thermocouples be used in reducing atmospheres?
No, Type K thermocouples should not be used in reducing, sulfurous, or vacuum environments unless they are protected by a suitable sheath material. Type N thermocouples offer better stability in such conditions.
What is the output voltage of a Type K thermocouple?
The output voltage of a Type K thermocouple depends on temperature. Some approximate values (referenced to 0ºC) are:
100ºC → 4.096 mV
500ºC → 20.644 mV
1000ºC → 41.276 mV
For a detailed conversion, refer to the Type K Thermocouple Output Table.
What color code is used for Type K thermocouples?
IEC 60584-3 (International Standard) → Green outer sheath, green (+), white (-)
ANSI (USA Standard) → Yellow outer sheath, yellow (+), red (-)
What sheath materials are recommended for Type K thermocouples?
The choice of sheath material depends on the environment:
Stainless Steel 316 - General use, oxidation resistance
Inconel 600 - High-temperature applications up to 1250ºC
Ceramic Sheath - Extreme temperatures above 1300ºC
PFA/FEP Insulated - Low-temperature applications
For detailed information on sheath materials, please see our thermocouple sheath materials page.
How can I extend the life of a Type K thermocouple?
To maximize lifespan:
Use an appropriate sheath for the environment
Avoid exposure to reducing atmospheres
Use a proper cold junction compensation
Perform regular calibration
What is the difference between Type K and Type N thermocouples?
Both are nickel-based thermocouples, but Type N offers:
Better resistance to drift at high temperatures
Improved stability in reducing atmospheres
Less oxidation-related degradation
If high-temperature stability is required, Type N is preferred over Type K.