A comprehensive guide to Type K Thermocouples
Overview
At Labfacility, we specialise in providing high quality Type K thermocouples, known for their reliability and precision in various industrial applications. Our Type K thermocouples are engineered to deliver accurate temperature readings under challenging conditions, making them the go to choice for professionals across multiple industries.
What is a Type K Thermocouple?
A Type K thermocouple is a type of temperature sensor consisting of two dissimilar metals, Nickel-Chromium (Chromel) and Nickel-Alumel (Alumel), joined together at one end to create a measuring junction. When exposed to temperature changes, it generates a voltage that can be interpreted to measure temperature accurately.
Type K thermocouple working principle
The Type K thermocouple operates on the Seebeck effect, using Chromel and Alumel metals to create a junction that produces a voltage proportional to temperature differences between a hot (measuring) junction and a cold (reference) junction (Fig 1). This voltage, generated along the wires rather than at the junctions themselves, is small and requires precise instruments for accurate temperature measurement, particularly at extreme temperatures. Adjustments are made when the reference junction is at a temperature other than 0°C to calculate the actual temperature difference, ensuring accurate readings.
Why Use Type K Thermocouples?
- Wide Temperature Range: Type K thermocouples can measure temperatures from -200°C to +1260°C, making them suitable for a broad range of applications.
- Durability: The combination of Nickel-Chromium and Nickel-Alumel materials ensures excellent durability and resistance to oxidation.
- Cost-Effectiveness: Type K thermocouples are affordable and provide a good balance between cost and performance.
- Stability and Reliability: They offer stable and reliable measurements, even in harsh environments.
- Interchangeable: Type K thermocouples are the most common sensor used so it is easy to find compatible instrumentation
How Do I Know Which K Type Thermocouple I Have?
Identifying your K type thermocouple involves checking the following aspects:
- Colour Coding: Conductor Colours: The positive lead (Chromel) is usually coloured yellow (US standard) or green (IEC standard), while the negative lead (Alumel) is red (US standard) or white (IEC standard).
- Connector Type: Standard & Miniature Plugs: Typically, K type thermocouples use green plugs for IEC (European Standards and Yellow connectors for US (ANSI) standards
- Output mV: Approximately 41 µV/°C (Typically in the region of84 mV at ambient temperatures)
For full thermocouple connector colour codes click here
Insulation Material: Insulation Colours and Types: PVC, Fiberglass, PFA, PTFE or ceramic insulation has colour markings that conform to standard thermocouple type identifications.
For full thermocouple wire colour codes click here
Styles of Type K Thermocouples
Type K thermocouples come in various styles to suit different applications and environments:
- Bare Wire Thermocouples: Simple and cost-effective, suitable for applications where the thermocouple is protected from the environment.
- Probes with Connectors: Encapsulated probes with standard connectors for easy attachment to measurement devices.
- Surface Thermocouples: Designed to measure surface temperatures, often with a flat or flexible probe.
- Handheld Thermocouples: These probes are use with handheld digital indicators where portable temperature measurement is required.
- Immersion Thermocouples: Suitable for measuring temperatures in liquids, typically encased in protective sheaths.
- High-Temperature Thermocouples: Specifically designed for extreme temperatures, often using ceramic insulations and rugged materials.
- Miniature Thermocouples: Compact, with fine wire, suitable for small or confined spaces where larger sensors would be impractical.
- Mineral insulated Thermocouples: A robust and semi flexible material allows type K thermocouple to be used at high temperatures and long lengths that can be bend into shape.
- Screw in Thermocouples – A range of thermocouples with various thread options to screw into machinery, metal work and casings.
General Product Specifications for Type K Thermocouples
| Thermocouple Type: | K (Nickel-Chromium/Nickel-Alumel) |
| Temperature Range: | -200°C to +1260°C |
| Insulation Operations: | PVC, Fiberglass, PFA, ceramic, Mineral Insulated Metal Sheath (MIMS) |
| Probe Configurations: | Standard, heavy-duty, and miniature options to suit various applications. |
| Junction Types: | Available in grounded, ungrounded, and exposed junctions. |
| Thermocouple Voltage Output: | Type K thermocouples have a Seebeck coefficient of approximately 41 µV/°C. |
| Accuracy: | Typically, within 1.5°C or ±0.4% whichever is greater for Class 1 or ±2.2°C or ±0.75% of reading, whichever is greater. |
Colour Codes for Type K Thermocouple Wires
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| IEC Type K Thermocouple Cable | ANSI Type K Thermocouple Cable | JIS Type K Thermocouple Cable |
Colour Codes for Type K Thermocouple Connectors
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| IEC Type K Thermocouple Connectors | ANSI Type K Thermocouple Connectors | JIS Type K Thermocouple Connectors |
Advantages and Disadvantages of Type K Thermocouples
| ADVANTAGES | DISADVANTAGES |
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Wide Temperature Range: -200°C to +1260°C |
Less Accurate: Slightly less accurate compared to some other types like Type T or Type J |
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Durable: Excellent resistance to oxidation |
Not Suitable for Low Temperatures: Less accurate at extremely low temperatures. |
| Cost-Effective: Affordable and widely available |
Calibration Drift: Can suffer from calibration drift over time, especially at high temperatures. |
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Versatile: Suitable for many industrial applications |
Noise Sensitivity: Can be more sensitive to electrical noise, affecting readings. |
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Fast Response Time: Quick response to temperature changes |
Material Compatibility: Not suitable for use with certain materials that can cause degradation. |
Typical Applications
A common question is ‘What are type K thermocouples used for?’ Labfacility Type K thermocouples are essential for precision temperature measurement in diverse fields, such as:
- Industrial Ovens & Furnaces: Monitor and control high-temperature processes efficiently.
- Plastic Manufacturing: Ensure accurate temperature readings during extrusion and moulding.
- Aerospace: Critical for testing and monitoring engine temperatures and other high-stress components.
- Automotive: Ideal for exhaust gas temperature measurement and engine diagnostics.
- R&D: Type K thermocouple are used in Research & Development including laboratories, calibration and test centres
- Pharmaceuticals: K type thermocouple are used in industrial pharma manufacturing
- OEM: Many Original Equipment manufacturers utilise type K thermocouple as part of their products supplied by Labfacility
Type K thermocouple voltage chart
Click here to see the full thermocouple output characteristics emf v temperature table for type K thermocouples to international standards IEC 584-1 :2013
What is the response time of a type K Thermocouple
The response time for a Type K thermocouple is usually defined as the time taken for the thermal voltage (output) to reach 63% of maximum for the step change temperature in question. Type K thermocouple response times depend on several parameters, including the thermocouple dimension, construction, tip configuration, and the nature of the medium in which the sensor is located. If the Type K thermocouple is plunged into a medium with a high thermal capacity and rapid heat transfer, the effective response time will closely match the thermocouple's intrinsic response time.
Click here to see the table for typical response times for Mineral insulated type K thermocouples
Customisation Options
We offer bespoke solutions to meet your specific requirements. Whether you need unique probe lengths, specific junction types, or have specialised requirements to your own specification or drawings, Labfacility can provide customised Type K thermocouples tailored to your needs.
Click here to fill in our custom sensor build form and submit your requirements to our sales team.
Commitment to Quality
With over 50 years of experience in temperature measurement solutions, Labfacility is dedicated to delivering products that meet the highest standards of quality and reliability. Our Type K thermocouples undergo rigorous testing to ensure they perform flawlessly in your applications.
View our company brochure here.
Get in Touch
For more information on our Type K thermocouples or to discuss your specific requirements, please contact our expert team today.