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Thermokoppel type K versus Thermokoppel type S

Thermocouples are indispensable tools in the world of temperature measurement, especially in industrial applications. In this article, we will discuss the differences between two commonly used thermocouples, type K and type S. You can read about this and more in this blog.

What is a thermocouple?

Thermocouples work on the principle of comparative measurements.A thermocouple is composed of two metal conductors of different materials, which are connected at the measurement point. Depending on the material combination, they generate levels of thermoelectric voltage.

Different material combinations give different levels and of voltage, making them suitable for different temperature ranges.

The most common thermocouples are type K, J, L and S.


To make an informed choice between Type K and Type S thermocouples, it is crucial to thoroughly understand the specifications of both types.
Here are detailed specifications for both thermocouples.

Type K Thermocouple (NiCr-Ni)

  •  Positive conductor: Chromel (NiCr). Consists mainly of chromium (about 90%) and a small percentage of nickel.
  •  Negative conductor: Alumel (Ni). Consists mainly of nickel (about 95%), aluminum, silicon and manganese.
  •  Measuring range: Type K offers a wide measuring range, from -200°C to +1350°C. They are suitable for both low and high temperatures.
  •  Accuracy: Type K has an accuracy of approximately 41 μV/°C, making it suitable for many applications where precision is essential.
  •  Corrosion resistance: Type K is resistant to various environmental conditions, including oxidation, corrosion, and mild chemicals.
Type K thermokoppel

Type K thermokoppel

Type S Thermocouple (Pt10Rh-Pt)

  •  Positive Conductor: Platinum/Rhodium (Pt10Rh). Consists mainly of platinum (±90%) and a small percentage of rhodium (±10%).
  •  Negative conductor: Platinum (Pt).Consists of 100% platinum.
  •  Measuring range:Type S offers a remarkably wide measuring range, covering temperatures up to 1600°C.
  •  Accuracy:Type S is known for its high accuracy, with a sensitivity of about 10 μV/°C. This makes them ideal for applications where precision is critical.
  • Corrosion resistance: Type S is resistant to oxidation and corrosion, even at high temperatures, and have a longer service life.
type S thermokoppel

Type S thermokoppel

Advantages of type K and type S thermocouples

Advantages of type K thermocouple

Type K offers several advantages that make it suitable for a variety of applications.

  •  Wide measuring range

Type K thermocouples have an extended temperature range, from -200°C to +1350°C, which makes them suitable for both low and high temperature measurements.

  •  High accuracy

Type K has high accuracy, with a thermal sensitivity of up to 41 μV/°C.This makes them reliable for precision temperature measurements.

  •  Resistance to corrosion

Type K thermocouples have reasonably good resistance to corrosion, making them suitable for use in a variety of environments, including chemical and industrial applications.

  •  Affordability.

They are cost-effective and offer excellent performance for the price, making them a popular choice in various industries.

  •  Fast response time

Type K thermocouples have a fast response time, which is essential for processes that require immediate temperature measurements.

Advantages of Type S thermocouple

Type S offers specific advantages that make it suitable for demanding applications.
  • High temperature measurements

Type S is designed for extremely high temperature measurements, up to 1600°C. This makes them suitable for applications in industrial furnaces, melting processes and other high-temperature applications.

  • High accuracy

Type S offers impressive accuracy even at these extreme temperatures, with a sensitivity of about 10 μV/°C.

  •  Long life

Type S consists of precious metals. With a ceramic sheath, it is highly resistant to corrosion, ensuring longer life even in demanding conditions.

  •  Stability

Type S remains stable and reliable over extended periods of time, making them suitable for continuous temperature measurements.

  •  Application Diversity

Type S is suitable for a variety of environments, including oxidizing, inert and vacuum environments, making them versatile.

Disadvantages of type K thermocouple

Although type K has many advantages, there are also some disadvantages to consider.

  • Sensitivity to contamination

Type K can be sensitive to contamination. Exposure to contaminants, such as sulfur-containing gases, can reduce measurement accuracy.

  • Limited accuracy at low temperatures.

At temperatures below freezing, the accuracy of Type K thermocouples can be reduced. For low-temperature applications, other thermocouples may be more suitable.

  • Not suitable for high-temperature oxidative atmospheres

Although type K thermocouples are generally resistant to oxidation, they may have limited life at very high temperatures in oxidative atmospheres.

  • Magnetic sensitivity

Type K thermocouples are magnetic, which means they can be affected by magnetic fields. In some applications, this can be a disadvantage.

  • Corrosion.

Galvanic corrosion can occur on contact with other metals, especially in humid environments. Oxygen deficiency can lead to insufficient Ni-oxidation (green discoloration). This can affect the life of the thermocouple.

  • Less stable at high temperatures

At very high temperatures, Type K thermocouples may be less stable compared to some other thermocouple types.

Disadvantages of type S thermocouple

Although type S has many advantages, there are also some disadvantages to consider.

  • High cost

Type S thermocouples are often considered more expensive compared to some other thermocouple types. Platinum and rhodium are precious metals with a higher cost.

  • Not suitable for low temperatures

Type S thermocouples are less suitable for applications in which low temperatures must be measured. For low-temperature applications, other thermocouples may be more suitable.

  • Platinum poisoning

Unprotected thermocouples should not be used in continuous operation above 1500 °C.

Platinum poisons, such as Silicon, Aluminum, Sulfur and Phosphorus can affect service life.

When selecting a thermocouple type for a specific application, it is important to consider environmental conditions, desired accuracy and temperature range. In some cases, thermocouples of other types may be better suited for specific applications.
In summary, the type K thermocouple offers broad applicability and cost-effectiveness, while the type S thermocouple excels in high-temperature measurements and accuracy.
Choosing the right thermocouple depends on the specific requirements of your application and the temperature range to be measured.



Type K

Type S


Chromel and Alumel

Platinum and Rhodium

Measuring range

-200°C to +1350°C

0 to 1600°C


to 41 μV/°C

Ongeveer 10 μV/°C






Moderate Excellent

Response time




Applications of Type K Thermocouple

Type K thermocouples are widely used in various industrial applications, including melting furnaces, heat treatment processes, HVAC systems and food processing.

Applications of Type S Thermocouple

Type S thermocouples are often used in situations where high temperatures and extreme precision are required, such as in the aerospace, metallurgy, petrochemical, and scientific research industries.
Type S thermocouples are also ideal for use in processes where temperature measurements are critical for product quality and safety, such as in the pharmaceutical and biotechnology industries.
In addition, we find them in laboratory environments where accurate temperature measurements are essential for research and development.

Which thermocouple should you choose?

Now that you are familiar with the specifications and applications of Type K and Type S thermocouples, you may want to know which thermocouple is best suited for your specific needs. Choosing the right thermocouple is critical to obtaining accurate temperature readings and ensuring the performance and safety of your processes.

Here are some considerations to help you decide which thermocouple is best for your application.

  •  Temperature range.

Consider the temperature requirements of your process.

If you need to measure temperatures up to 1200°C, Type K may be the best choice.

For even higher temperatures up to 1600°C, type S is appropriate.

  • Accuracy

If your application requires high precision, type S with its highly accurate measurements is a good choice, but type K offer good accuracy for many applications.

  • Service life and durability

If your process environment is corrosive, or if the thermocouple is exposed to wear, Type S with its better corrosion resistance and longer life may be preferred.

  • Application area

Consider the industry and application in which you work.

  • Budget

The cost aspect is important. Type K thermocouples tend to be more affordable than Type S.

  • Availability of accessories

Check whether the necessary accessories, such as measuring instruments and compensation cables, are available for the selected type of thermocouple.

  • Norms and standards

Consider the norms and standards applicable in your industry.Ensure that the selected thermocouple meets the required standards.

It is essential to thoroughly evaluate your specific needs and the environment in which the thermocouple will be used before making a choice. You can also consult with our temperature measurement experts to determine the best thermocouple for your application.

By choosing the right thermocouple, you can make accurate temperature measurements and ensure that your processes run smoothly, contributing to product quality and safety.


In this article, we have highlighted the differences between Type K and Type S thermocouples, discussing both specifications and applications. Both thermocouples have their unique advantages and disadvantages and are suitable for different industrial environments.

Understanding these differences is essential to choosing the right thermocouple for your specific application.

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About the Author

My name is Saskia van der Laan, I have been working for JUMO for over 33 years. Since 2012 I have been working with great enthusiasm in the marketing department. It is my passion to use written text to translate technology into practice with the aim of informing and inspiring the reader.


Asma Veghar - Marketing

Technical specialist

Cees Nooij - Technical specialist +31294491487 +31294491487